My Human Anatomy and Physiology Notes

Lect 1

Introduction to Human Anatomy and Physiology

1. Define anatomy.

Ana=up, Tome=cut

Anatomy is defined as the study of body structure. In some words, it means to cut apart. Subdivisions for anatomy: surface, gross/macroscopic, systemic, radiographic, developmental, embryology, cytology, pathological, microscopic, regional

2. Define physiology.

Physio=nature, Logy=study

Physiology is defined as the study of body functions. Subdivisions for physiology: cells, systems, patho- , exercise, neuro- , endocrinology, cardiovascular, immuno- , respiratory, renal, reproductive

3. Determine 6 levels of organisations.

Chemical level: subatomic particles>atoms>molecules>elements

Cellular level

Tissue level: groups of similarly specialized cells and the substances s surrounding them that usually arise from a common ancestor and perform certain special functions.

Organ level: two or more tissues with specific functions

Organ system level: related organs with common function

integumentary, skeletal, muscular, nervous, endocrine, cardiovascular, lymphatic respiratory, urinary, digestive, and reproductive

Organismal level

4. Determine the anatomical position.

Standardized method of observing/imaging body that allows precise and consistent anatomical references.

a. stand upright

b. facing observer, head level

c. eyes face forward

d. feet flat on floor, legs parallel

e. arms at the sides

f. pulms turned forward (ventral)

5. Briefly explain about the importance of anatomical position.

Anatomical position is the position of reference for anatomical nomenclature. It creates a common point of reference for all who study the human body.

Prone position: body lying face down

Supine position: body lying face up

6. Determine the regional names.

cranial (skull),thoracic (chest),brachial (arm), patellar (knee), cephalic (head), gluteal (buttock)

7. Briefly explain about the planes.

Planes are imaginary flat surfaces that are used to divide the body or organs into definite areas.

A. Sagittal/lateral分左右

Midsagittal: equal

Parasagittal: unequal

B. Transverse/axial/cross-sectional/horizontal分上下

Superior: towards head

Anterior: away from head

C. Coronal/frontal分前后

Anterior/ventral前

Posterior/dostal后

D. Oblique斜割

E. Others

Medial: near to midline of body

Lateral: further from midline

Proximal: near to attachment of limbs(legs and arms) to trunk(chest, abdomen, pelvis)

Distal: further from the attachment of limbs to trunk

Cranial: head end

Caudal: tail end

Dorsal: 

Unilateral: on one side

Bilateral: on both sides

Acute: symptoms worsen rapidly

Chronic: develops and worsen over an extended period of time

Ipsilateral: on same side as another structure

Contralateral: on opposite side

Superficial: near outer body surface

Intermediate: between 2 structure

Deep: further from body surface

Avascular: without blood circulation

Ectopic: occur in abnormal position

Flexion上移

Extension下摆

Abduction: move body part away from midline

Adduction: move body part forward to midline

Internal and external rotation: rotate towards or further from body center

8. Briefly explain about section.

Sections are the flat surfaces resulting from cuts through body structures, named according to the plane on which the cut is made.

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9. Determine the organs in abdominal cavity, pelvic cavity, pleural cavity, pericardial cavity, thoracic cavity, and mediastinum.

Ventral body cavity:

Abdominopelvic cavity is divided into superior abdominal and inferior pelvic cavity.

a.       Abdominal cavity: small intestine, most of large intestine, spleen, kidneys, stomach, pancreas, liver gallbladder , digestive and renal systems, endocrine system, adrenal glands, etc

b.      Pelvic cavity: reproductive systems (ovary, testes), urinary bladder, pelvic colon, rectum, anus, etc

Thoracic cavity contains 2 pleural cavities,  and mediastinum which includes pericardial cavity. It includes organs such as ribs, sternum, vertebral column, muscle, heart, lungs, etc

a.       Pleural cavity: enclose the lungs

b.      Pericardial cavity: surround the heart

c.       Mediastinum: heart and great vessels, esophagus, trachea, thymus, sternum, thoracic vertebrae and nerves, etc

 10. Define visceral peritoneum, parietal peritoneum, visceral pericardium, parietal pericardium, visceral pleura, and parietal pleura.

Visceral peritoneum: serous membrane that covers the abdominal viscera (internal organs).

Parietal peritoneum: serous membrane that lines the abdominal wall.

Visceral pericardium: epicardium. Composed of a single layer of serosal investment covering entire heart.

Parietal pericardium: lines the inner surface of fibrous pericardium. Composed of a serosal lining and a fibrous sac.

Visceral pleural: delicate membrane that covers the lungs.

Parietal pleural: outer membrane attached to the internal surface of thoracic cavity.

11. Determine 9 abdominopelvic regions.

Lect 3

Cellular level of organisation

1. Cell.

Cell is the basic, living, structural, and functional unit of body.

Cytology is the study of cell structure, and cell physiology is the study of cell function.

Cell can be divided into 3 principal: plasma membrane, cytoplasm(cytosol, organelles), nucleus

2. Plasma membrane.

flexible, sturdy barrier that surrounds and contains cytoplasm

fluid mosaic model describes its structure

membrane 50% lipid 50% protein and held together by hydrogen bond

lipid is barrier to entry or exit of polar substances

protein are "gatekeepers" regulate trafic

Function:

a. formation of channel: paasageway to allow specific substances pass through

b. transporter protein: bind a specific substance, change their shape & move it across membrane

c. receptor proteins: cellular recognition site, bind to substance

d. act as enzyme: speed up reaction

e. linker: anchor proteins, allow cell movement, cell shape & structure

f. cell identify marker: allow cell to recognize other similar cells

Membrane permeability:

a. selectively permeable: some can pass through

b. lipid bilayer portion is permeable to small, nonpolar, uncharged molecules but impermeable to ions and charged or polar molecules

c. permeable to water

d. transmembrane protein acts as channel/transporter increase permeability

e. vesicular transport allow macromolecule to pass through 

Gradient:

a. concentration gradient: difference in concentration of a chemical btwn 1 side of plasma membrane & the other

b. electrical gradient: O2 & Na are more concentrated outside the cell membrane with CO2 & K more concentrated inside membrane

Transport

a. diffusion:

• Diffusion is the random mixing of

particles that occurs in a solution as a

result of the kinetic energy of the

particles. (Figure 3.6)

• Nonpolar, hydrophobic molecules

such as respiratory gases, some

lipids, small alcohols, and ammonia

can diffuse across the lipid bilayer.

• It is important for gas exchange,

absorption of some nutrients, and

excretion of some wastes.

b. osmosis:

• Osmosis is the net movement of a solvent through a selectively permeable membrane, or  in living systems, the movement of water (the solute) from an area of higher concentration to  

an area of lower concentration across the membrane (Figure 3.7).  

• Water molecules penetrate the membrane by diffusion through the lipid bilayer or through aquaporins, transmembrane proteins that function as water channels. 

• Water moves from an area of lower solute concentration to an area of higher solute concentration. 

• Osmosis occurs only when the membrane is permeable to water but not to certain solutes.

c. active transport:

• Active transport is an energy-requiring

process that moves solutes such as ions,

amino acids, and monosaccharides

against a concentration gradient.

d. endocytosis:

• In endocytosis, materials move into a cell in a  vesicle formed from the  plasma membrane. 

• Receptor-mediated endocytosis is the  

selective uptake of large molecules and particles  by cells 

• Endocytosis = bringing something into cell

– phagocytosis = cell eating by macrophages & WBCs

• particle binds to receptor protein

• whole bacteria or viruses are engulfed & later digested

– pinocytosis = cell drinking

• no receptor proteins

• The steps of receptor-mediated endocytosis includes binding, vesicle

formation, uncoating, fusion with endosome , recycling of receptors, and

degradation in lysosomes..

• Viruses can take advantage of this mechanism to enter cells.

e. pinocytosis: ingestion of extracellular fluid

• No pseudopods form

• Nonselective drinking of

extracellular fluid

f. phagocytosis: ingestion of solid particles

• Pseudopods extend to form

phagosome

• Lysosome joins it

g. exocytosis:

• Exocytosis = release something from cell

• Vesicles form inside cell, fuse to cell membrane

• Release their contents

– digestive enzymes, hormones, neurotransmitters or

waste products

• replace cell membrane lost by endocytosis

• In exocytosis, membrane-enclosed structures called

secretory vesicles that form inside the cell fuse with the

plasma membrane and release their contents into the

extracellular fluid.

• Transcytosis may be used to move a substance into, across

and out of a cell.

3. Cytoplasm.

Cytosol: intracellular fluid, semifluid portion that contains inclusions and dissloved solutes, composed mostly water, plus proteins, carbohydrates, lipids and inorganic substances, chemical in it are either in solution/colloidal(suspended) form, functionally, medium for metabolic reaction.

4. Organelles.

a. cytoskeleton

• Network of protein filaments

throughout the cytosol

• Functions

– cell support and shape

– organization of chemical

reactions

– cell & organelle movement

• Continually reorganized

b. microfilaments

• Most microfilaments are composed of actin and function in

movement and mechanical support

• Intermediate filaments are composed of several different

proteins and function in support and to help anchor

organelles such as the nucleus

• Microtubules are composed of a protein called tubulin and

help determine cell shape and function in the intracellular

transport of organelles and the migration of chromosome

during cell division.

c. centrosomes

• Centrosomes are dense areas of

cytoplasm containing the

centrioles, which are paired

cylinders arranged at right angles

to one another, and serve as

centers for organizing

microtubules in interphase cells

and the mitotic spindle during

cell division

d. cilia & flagella

• Cilia are numerous, short, hair-like

projections extending from the

surface of a cell and functioning to

move materials across the surface of

the cell (Figure. 3.17a – 3.17b).

• Flagella are similar to cilia but are

much longer; usually moving an

entire cell. The only example of a

flagellum in the human body is the

sperm cell tail (Figure 3.17c).

e. ribosome

• Ribosomes are tiny spheres consisting of ribosomal RNA and several

ribosomal proteins; they occur free (singly or in clusters) or together with

endoplasmic reticulum (Fig 3.18).

• Functionally, ribosomes are the sites of protein synthesis.

• Composed of Ribosomal RNA & protein

• Free ribosomes are loose in cytosol

– synthesize proteins found inside the cell

• Membrane-bound ribosomes

– attached to endoplasmic reticulum or nuclear membrane

– synthesize proteins needed for plasma membrane or for export

– 10 to 20 together form a polyribosome

• Inside mitochondria, ribosomes synthesize mitochondrial proteins

f. ribosomal subunits

• Large + small

subunits

– made in the

nucleolus

– assembled in the

cytoplasm

g. ER

• The endoplasmic reticulum (ER) is a network of

membranes that form flattened sacs or tubules

called cisterns (Figure 3.19).

• Rough ER is continuous with the nuclear

membrane and has its outer surface studded with

ribosomes.

• Smooth ER extends from the rough ER to form a

network of membrane tubules but does not

contain ribosomes on its membrane surface.

• The ER transports substances, stores newly

synthesized molecules, synthesizes and packages

molecules, detoxifies chemicals, and releases

calcium ions involved in muscle contraction

h. Golgi complex

• The Golgi complex consists of three to twenty stacked,

flattened membranous sacs (cisterns) referred to as cis,

medial, and trans (Figure 3.20).

• The principal function of the Golgi complex is to process,

sort, and deliver proteins and lipids to the plasma

membrane, lysosomes, and secretory vesicles

i. lysosome

• membrane-enclosed vesicles

that contain powerful digestive

enzymes (Figure 3.22).

– internal pH reaches 5.0

• Functions

– digest foreign substances

– autophagy (autophagosome

forms)

• recycles own organelles

– autolysis

• lysosomal damage after

death

j. perioxosome

• Peroxisomes are similar in structure to lysosomes, but are

smaller.

• They contain enzymes (e.g., catalase) that use molecular

oxygen to oxidize various organic substances.

– part of normal metabolic breakdown of amino acids and fatty

acids

– oxidizes toxic substances such as alcohol and formaldehyde

– contains catalase which decomposes H2O2

k. mitochondria

• The mitochondrion is bound by a double

membrane.

• The outer membrane is smooth with the inner

membrane arranged in folds called cristae

• Mitochondria are the site of ATP production in

the cell by the catabolism of nutrient molecules.

• Mitochondria self-replicate using their own DNA.

• Mitochondrial DNA (genes) are usually inherited

only from the mother.

5. Nucleus.

Nucleus usually is most prominent feature of cell, most body cells have a single nucleus; some (red blood cells)

have none, whereas others (skeletal muscle fibers) have several.

• The parts of the nucleus include the nuclear envelope which is perforated by channels called nuclear pores, nucleoli, and genetic  material (DNA), 

• Within the nucleus are the cell’s hereditary units, called genes,  which are arranged in single file along chromosomes.

Function:

• 46 human DNA molecules or chromosomes

– genes found on chromosomes

– gene is directions for a specific protein

• Non-dividing cells contain nuclear chromatin

– loosely packed DNA

• Dividing cells contain chromosomes

– tightly packed DNA

– it doubled (copied itself) before condensing

• Each chromosome is a long molecule of DNA that is  coiled together with several  proteins (Figure 3.25). 

• Human somatic cells have 46 chromosomes arranged  in 23 pairs. 

• The various levels of DNA packing are represented by nucleosomes, chromatin fibers, loops, chromatids, and chromosomes.

6. Protein synthesis.

• Much of the cellular machinery is devoted to synthesizing

large numbers of diverse proeins.

• The proteins determine the physical and chemical characteristics of cells. 

• The instructions for protein synthesis is found in the DNA in the nucleus. 

• Protein synthesis involves transcription and translation

7. Cell division.

• Cell division is the process by which cells reproduce

themselves. It consists of nuclear division (mitosis and

meiosis) and cytoplasmic division (cytokinesis).

• Cell division that results in an increase in body cells is called

somatic cell division and involves a nuclear division called

mitosis, plus cytokinesis.

• Cell division that results in the production of sperm and eggs

is called reproductive cell division and consists of a nuclear

division called meiosis plus cytokinesis.

Control of cell density:

• The three possible destinies of a cell are to remain alive and

functioning without dividing, to grow and divide, or to die.

• Maturation promoting factor (MPF) induces cell division.

• Cell death, a process called apoptosis, is triggered either

from outside the cell or from inside the cell due to a “cell-

suicide” gene.

• Necrosis is a pathological cell death due to injury.

• Tumor-suppressor genes can produce proteins that normally

inhibit cell division resulting in the uncontrollable cell growth

known as cancer.

8. Cellular diversity.

• Not all cells look alike, nor do

they perform identical functional

roles in the body.

• The cells vary considerably

– 100 trillion cells in the body --

200 different types

– Vary in size and shape related to

their function

9. Cells and Aging.

• Aging is a normal process accompanied by a progressive

alteration of the body’s homeostatic adaptive responses;

• The physiological signs of aging are gradual deterioration in

function and capacity to respond to environmental stresses.

• These signs are related to a net decrease in the number of

cells in the body and to the dysfunctioning of the cells that

remain.

• The extracellular components of tissues (e.g., collagen fibers

and elastin) also change with age.

10. Disorders: homeostatic imbalance.

• Cancer is a group of diseases characterized by uncontrolled

cell proliferation.

• Cells that divide without control develop into a tumor or

neoplasm.

• A cancerous neoplasm is called a malignant tumor or

malignancy. It has the ability to undergo metastasis, the

spread of cancerous cells to other parts of the body. A

benign tumor is a noncancerous growth.

• Hyperplasia = increased number of cell divisions

– benign tumor does not metastasize or spread

– malignant---spreads due to cells that detach from tumor and

enter blood or lymph

Lect 4

Tissue level of organisation

1. Define tissue.

– a group of similar cells

– usually have a similar embryological origin

– are specialized for a particular function.

2. Determine types of tissue.

• Epithelial tissue

– covers body surfaces, lines hollow organs, body cavities, and ducts; and forms glands. 

• Connective tissue

– protects and supports the body and its organs, binds organs together, stores energy reserves as fat, and  provides immunity. 

• Muscle tissue

– is responsible for movement and generation of force.

• Nervous tissue

– initiates and transmits action potentials (nerve impulses) that help coordinate body activities.

3. Determine general features of epithelial tissue.

• Closely packed cells with little extracellular material

• Cells sit on basement membrane

• Avascular---without blood vessels

• Good nerve supply

• Rapid cell division (high mitotic rate)

• Functions

– protection, filtration, lubrication, secretion, digestion, absorption, transportation, excretion, sensory  reception, and reproduction.

4. Determine types of epithelium.

• Covering and lining epithelium

– epidermis of skin

– lining of blood vessels and ducts

– lining respiratory, reproductive, urinary & GI tract

• Glandular epithelium

– secreting portion of glands

– Ex: thyroid, adrenal, and sweat glands

5. Determine classification of epithelium.

• Classified by arrangement of cells into layers

– simple = one cell layer thick

– stratified = two or more cell layers thick

– pseudostratified = cells contact basal membran but all cells don’t reach apical surface 

• nuclei are located at multiple levels so it looks multilayered 

• Classified by shape of surface cells

– squamous =flat

– cuboidal = cube-shaped

– columnar = tall column

– transitional = shape varies with tissue stretching

6. Simple squamous epithelium.

– Single layer of flat cells

– nuclei are centrally located

– Cells are in direct contact with each other.

– Endothelium lines the heart and blood vessels.

– Mesothelium lines the thoracic and abdominopelvic cavities and covers the organs within them.

7. Simple cuboidal epithelium.

• Single layer of cube-shaped cells viewed from the side

– nuclei are round and centrally located

– lines tubes of kidney

8. Nonciliated simple columnar epithelium.

• Single layer rectangular cells

• Unicellular glands (goblet cells) secrete mucus-lubricate GI, respiratory, reproductive and urinary systems 

• Microvilli -adapted for absorption in GI tract (stomach to rectum)

• goblet cells secrete mucus

9. Ciliated simple columnar epithelium.

• Single layer rectangular cells with cilia

• Unicellular glands (goblet cells) secrete mucus

• Cilia (motile membrane extensions) move mucous

– found in respiratory system and in uterine tubes

10. Pseudostratified ciliated columnar epithelium.

• Single cell layer of cells of variable height

– Nuclei are located at varying depths (appear layered.)

– Found in respiratory system, male urethra & epididymis

• All cells are attached to the basement membrane but some do not reach the apical surface. 

• the cells that reach the surface either secrete mucus (goblet cells) or bear cilia that sweep away mucus and trapped foreign particles. 

• Pseudostratified nonciliated columnar epithelium contains no cilia or goblet cells.

11. Stratified epithelium.

• Epithelia have at least two layers of cells.

– more durable and protective

– name depends on the shape of the surface (apical) cells

12. Stratified squamous epithelium.

• Stratified squamous epithelium consists of several layers of

– top layer of cells is flat

– deeper layers of cells vary cuboidal to columnar basal cells replicate by mitosis 

• Keratinized stratified squamous epithelium

– surface cells dead and filled with keratin.

• skin (epidermis)

• Nonkeratinized epithelium

– no keratin in moist living cells at surface

• mouth, vagina

13. Stratified cuboidal epithelium.

• Multilayered

• Surface cells cuboidal

14. Stratified columnar epithelium.

• Multilayered

– columnar surface cells

– very large ducts

– part of male urethra

15. Transitional epithelium.

– Multilayered

– surface cells varying in shape

• round to flat (if stretched)

– lines the urinary bladder, lines portions of the ureters and the urethra.

16. Glandular epithelium.

• Exocrine glands

– Secrete their products into ducts that empty at the surface of covering and lining epithelium or directly onto a free surface 

– cells that secrete---sweat, ear wax, saliva, digestive enzymes onto free surface of epithelial layer 

– connected to the surface by tubes (ducts)

– unicellular glands or multicellular glands

• Endocrine glands

– ductless

– secrete hormones into the bloodstream

– hormones help maintain homeostasis

– Unicellular (single-celled) glands-goblet cells

– Multicellular glands-branched (compound) or unbranched (simple) tubular or acinar (flask-like) shape

17. Determine connective tissue.

abundant and widely distributed

derived from mesoderm & mesenchyme

– Immature cells have names that end in -blast( e.g., 

fibroblast, chondroblast)

– Mature cells have names that end in -cyte (e.g., 

osteocyte).

 

matrix

gel/viscous, liquid or solid

Good nerve & blood supply except in cartilage & tendons

– Fibroblasts (which secrete fibers and matrix)

– Adipocytes (or fat cells, which store energy in the form of

fat)

– White blood cells (or leukocytes)

Function: protect, support, connection, bind, storage, transportation, immune

18. Determine types of mature connective tissue.

fiber: collagen, elastic, reticular

connective tissue proper: loose, dense

cartilage: hyaline, elastic, reticular

bone tissue: compact & spongy/trabecular

blood and lymph

19. Loose connective tissue.

• Loosely woven fibers throughout tissues

• Sub-types of loose connective tissue

– areolar connective tissue

– adipose tissue

– reticular tissue

20. Areolar connective tissue.

• Cell types = fibroblasts, plasma cells, macrophages, mast cells and

a few white blood cells

• It is found in the subcutaneous layer of the integument

• Black = elastic fibers,

• Tan/Pink = collagen fibers

• Nuclei are mostly fibroblasts

21. Adipose tissue.

• Peripheral nuclei due to large fat storage droplet

• found wherever areolar connective tissue is located

• Deeper layer of skin, organ padding, yellow marrow

• Brown fat (found in infants) has more blood vessels and

mitochondria and is responsible for heat generation

22. Reticular connective tissue.

• Network of fibers & cells that produce framework of organ

• Holds organ together (liver, spleen, lymph nodes, bone marrow)

• Reticular connective tissue consists of fine interlacing reticular

fibers and reticular cells.

23. Dense regular connective tissue.

• Collagen fibers in parallel bundles with fibroblasts between bundles of

collagen fibers

• White, tough and pliable when unstained (forms tendons)

24. Dense irregular connective tissue.

• Collagen fibers are irregularly arranged

• Tissue can resist tension from any direction

• Very tough tissue -- white of eyeball, dermis of skin, heart

valves, the perichondrium, the tissue surrounding

cartilage, and the periosteum

25. Elastic connective tissue.

• Branching elastic fibers and fibroblasts

• Can stretch & still return to original shape

• Lung tissue, vocal cords, ligament between vertebrae

26. Hyaline cartilage.

• chondrocytes sit in spaces called lacunae

• has fine collagen fibers embedded in a gel-type matrix

• No blood vessels or nerves so repair is very slow

• affords flexibility and support

• Reduces friction at joints as articular cartilage

27. Fibrocartilage.

• Many more collagen fibers causes rigidity & stiffness

• contains bundles of collagen fibers in its matrix

• Strongest type of cartilage (intervertebral discs)

28. Elastic cartilage.

• Elastic fibers help maintain shape after

deformations

• contains a threadlike network of elastic fibers

• provides strength and elasticity

• Ear, nose, vocal cartilages

29. Liquid connective tissue.

Blood: liquid matrix called plasma, RBC(erythrocyte), WBC(leukocyte), cell fragments(platelets)

Lymph:

– Contains less protein than plasma

– Move cells and substances (eg., lipids) from one part of

the body to another

https://www.youtube.com/watch?v=4HNbspnFyIE

30. Determine nervous tissue.

composed of only 2 principal kinds of cells:

a. neurons(nerve cells)

consist cell body & 2 process: axon & dendrite

 

b. neuroglia(protective and supporting cells)

protect & support neurons 

often the sites of tumors 

Lect 5

Integumentary system

1. Function of integumentary system.
made up of skin and its accessory structure:
structure, function, growth and repair, development, aging
guard body's physical & biochemical integrity
maintain constant body temp.
provide sensory info about surrounding environment

2. Structure of skin.
• The superficial portion of the skin is the epidermis and is composed of  epithelial tissue. 

• The deeper layer of the skin is the dermis and is primarily composed of connective tissue. 

• Deep to the dermis is the subcutaneous layer or hypodermis. (not a part of the skin) 

– It consists of areolar and adipose tissue. 

– fat storage, an area for blood vessel passage, and an area of  pressure-sensing nerve endings.

3. 4 principle cells of epidermis.

• keratinocytes

– produce the protein keratin, which helps protect the skin and underlying tissue from heat, microbes, and chemicals,  and lamellar granules, which release a waterproof sealant  

• melanocytes

– produce the pigment melanin which contributes to skin color and absorbs damaging ultraviolet (UV) light 

• Langerhans cells

– derived from bone marrow

– participate in immune response

• Merkel cells

– contact a sensory structure called a tactile (Merkel) disc and function in the sensation of touch

4. Layers(strata) of epidermis.

Stratum corneum: barrier to light, heat, water, chemicals & bacteria, lamellar granules make it water-repellent

Stratum lucidum: contains precursor of keratin

Stratum granulosum: transition btwn deeper, metabolically active strata & dead cells of more superficial strata

Stratum spinosum: provides strength & flexibity 

Stratum basale: deepest single layer

5. Dermis.

connective tissue layer composed of collagen & elastic fibers, fibroblasts, macrophages & fat cells

contains hair follicles, glands, nerves, blood vessels

Structure:

• Epidermal ridges increase friction for better grasping ability and provide the basis for fingerprints and footprints. The ridges  typically reflect contours of the underlying dermis. 

• Lines of cleavage in the skin indicate the predominant direction of the underlying collagen fibers. Knowledge of these lines is  especially important to plastic surgeons.

6. Papillary region of dermis.
top 20% of dermis

areolar connective tisue containing fine elastic fibers, corpuscles of touch(Meissner's corpuscle), adipose cells, hair follicles, sebaceous glands, sudoriferous glands  

– The collagen and elastic fibers provide strength, extensibility (ability to stretch), and elasticity (ability to return to original shape after  stretching) to skin. 

Finger like projections are called dermal papillae

– anchors epidermis to dermis

– contains capillaries that feed epidermis

– contains Meissner’s corpuscles (touch) & free nerve endings for sensations of heat, cold, pain, tickle, and itch

7. Reticular region of dermis.

• Dense irregular connective tissue

• Contains interlacing collagen and elastic fibers

• Packed with oil glands, sweat gland ducts, fat & hair follicles

• Provides strength, extensibility & elasticity to skin

– stretch marks are dermal tears from extreme stretching

• Epidermal ridges form in fetus as epidermis conforms to dermal papillae 

– fingerprints are left by sweat glands open on ridges

– increase grip of hand

8. basis of skin color.

Jaundice: buildup of yellow bilirubin in blood from liver disease

Cyanosis: deoxyhemoglobin(hemoglobin depleted O2), bluish color to nail beds, lips, skin,

Erythema: redness of skin due to enlargement of capillaries in dermis during inflammation, infection, allergy or burns

9. skin color pigments.

melanin produced by melanocyte(convert tyrosine to melanin), UV in sunlight increase melanin production

carotene yellow-orange pigment(precursor of vitamin A), found in stratum corneum & dermis

hemoglobin red, O2 carry pigment, if other pigments are not present, epidermis is translucent so pinkness will be evident

10. accessory structures of skin.

develop from embryonic epidermis

cells sink inward during development to form: hair, oil glands, sweat glands, nails

11. structure and function of hair.

shaft-visible

root-below surface

follicle surrounds root

Function:

– Prevents heat loss

– Decreases sunburn

– Eyelashes help protect eyes 

– Touch receptors (hair root plexus) senses light touch

12. glands of skin.

a. sudoriferous/sweat gland

Eccrine: extansive distribution most area of skin.

– secretory portion is in dermis with duct to surface

– ducts terminate at pores at the surface of the epidermis.

– regulate body temperature through evaporation (perspiration)

– help eliminate wastes such as urea.

Apocrine: limited in distribution to the skin of the axilla, pubis, and areolae; their duct open into hair follicles. 

– secretory portion in dermis

– duct that opens onto hair follicle

– secretions are more viscous

b. ceruminous/wax gland

• Ceruminous glands are modified sudoriferous glands that  produce a waxy substance called cerumen.  

– found in the external auditory meatus

– contains secretions of oil and wax glands

– barrier for entrance of foreign bodies

• An abnormal amount of cerumen in the external auditory  meatus or canal can result in impaction and prevent sound  waves from reaching the ear drum (Clinical Application)

c. sebaceous/oil gland

• Sebaceous (oil) glands are usually connected to hair follicles; they are absent in the palms and soles 

• Secretory portion of gland is located in the dermis

– produce sebum

• contains cholesterol, proteins, fats & salts

• moistens hairs

• waterproofs and softens the skin

• inhibits growth of bacteria & fungi (ringworm)

• Acne

– bacterial inflammation of glands

– secretions are stimulated by hormones at puberty

d. mammary/milk gland

e. specialized exocrine gland

13. structure of nails

• Tightly packed keratinized cells

• Nail body

– visible portion pink due to underlying capillaries 

– free edge appears white

• Nail root

– buried under skin layers

– lunula is white due to thickened stratum basale 

• Eponychium (cuticle)

– stratum corneum layer

14. Determine types of skin.

Thin skin:

– covers all parts of the body except for the palms and palmar surfaces of the digits and toes. 

– lacks epidermal ridges

– has a sparser distribution of sensory receptors than thick skin.

Thick skin(0.6 to 4.5 mm) :

– covers the palms, palmar surfaces of the digits, and soles

– features a stratum lucidum and thick epidermal ridges

– lacks hair follicles, arrector pili muscles, and sebaceous glands, and has more sweat glands than thin skin.

15. Briefly explain about the functions of skin.

Thermoregulation

perspiration & evaporation: lower body temp., adjust flow of blood

exercise: more blood brought to surface helps lower temp. in moderate exercise: blood in shunted to muscles & body temp. rises with extreme exercise

shivering & constriction of surface vessels: raise internal temp.

blood reservoir: extensive network of blood vessels

protection: physical, chemical & biological barrier, 

cutaneous sensations: touch, pressure, vibration, tickle, heat, cold, and pain arise in skin

synthesis of vitamin D: activation of precursor molecule in skin by UV, enzymes in liver & kidneys modify activated molecule to produce calcitirol, most active form of VD, necessary V for absorption of Ca from food in gastrorintestinal tract

excretion: 400ml of water/day, small amounts salts, CO2, ammonia & urea

strength from collagen fiber & flexibility from elastic fiber

16. epidermal wound healing

• Abrasion or minor burn

• Basal cells migrate across the wound

• Contact inhibition with other cells stops migration

• Epidermal growth factor stimulates basal cells to divide and replace the ones that have moved into the wound 

• Full thickness of epidermis results from further cell division

17. deep wound healing

• When an injury extends to tissues deep to the epidermis, the repair process is more complex than epidermal healing, and scar formation results

a. inflammatory: macrophage, neutrophil, clot unite wound edges and WBCs arrive from dilated and more permeable blood vessel. A blood clot unites the  wound edges, epithelial cells migrate across the wound, vasodilatation and increased permeability of blood vessels  deliver phagocytes, and fibroblasts form

b. migratory: epithelial cells beneath the scab bridge the wound, fibroblasts begin scar tissue, and  damaged blood vessels begin to grow. During this phase,  tissue filling the wound is called granulation tissue

c. proliferative: angiogenesis, formation of tissue, capillaries complete, events of migratory phase intensify

d. maturation: scab sloughs off, epidermis restore to normal thickness, collagen fibers become more organized, fibroblasts begin to disappear, & blood vessels restore to normal

e. scar tissue formation: 

– hypertrophic scar remains within the boundaries of the original wound

– keloid scar extends into previously normal tissue

• collagen fibers are very dense and fewer blood vessels are present so the tissue is lighter in color

Fibrosis

18. Age related structural changes

• Collagen fibers decrease in number & stiffen

• Elastic fibers become less elastic

• Fibroblasts decrease in number

• decrease in number of melanocytes (gray hair, blotching)

• decrease in Langerhans cells (decreased immune

responsiveness)

• reduced number and less-efficient phagocytes

• Most of the changes occur in the dermis

– wrinkling, slower growth of hair and nails

– dryness and cracking due to sebaceous gland atrophy

– Walls of blood vessels in dermis thicken so decreased

nutrient availability leads to thinner skin as subcutaneous fat is lost

Lect 6

The skeletal system: bone tissue

1. Briefly explain about the skeletal system.

• Dynamic and ever-changing throughout life

• Skeleton composed of many different tissues

– cartilage, bone tissue, epithelium, nerve, blood forming tissue, adipose, and dense connective tissue

2. Describe the functions of bone.

• Supporting & protecting soft tissues

• Attachment site for muscles making movement possible 

• Storage of the minerals, calcium & phosphate -- mineral homeostasis  

• Blood cell production occurs in red bone marrow (hemopoiesis) 

• Energy storage in yellow bone marrow

3. Describe anatomy of long bone.

• diaphysis = shaft

• epiphysis = one end of a long bone

• metaphysis are the areas between the epiphysis and diaphysis and  include the epiphyseal plate in  growing bones. 

• Articular cartilage over joint surfaces acts as friction reducer &  shock absorber 

• Medullary cavity = marrow cavity

• Endosteum = lining of marrow cavity 

• Periosteum = tough membrane covering bone but not the cartilage

4. Describe histology of bone.

• A type of connective tissue as seen by widely spaced cells  separated by matrix 

• Bone (osseous) tissue consists of widely separated cells  surrounded by large amounts  of matrix. 

• These and a few other salts are deposited in a framework  of collagen fibers, a process  called calcification or  mineralization..

5. Describe cells of bone and matrix of bone.

Cells of bone • Osteoprogenitor cells ---- undifferentiated cells

– can divide to replace themselves & can become osteoblasts

– found in inner layer of periosteum and endosteum

• Osteoblasts--form matrix & collagen fibers but can’t divide

• Osteocytes ---mature cells that no longer secrete matrix

• Osteoclasts---- huge cells from fused monocytes (WBC)

– function in bone resorption at surfaces such as endosteum

Matrix • Inorganic mineral salts provide bone’s hardness

– hydroxyapatite (calcium phosphate) & calcium carbonate

• Organic collagen fibers provide bone’s flexibility

– their tensile strength resists being stretched or torn

– remove minerals with acid & rubbery structure results

• Bone is not completely solid since it has small spaces for

vessels and red bone marrow

– spongy bone has many such spaces

– compact bone has very few such spaces

6. Compact/dense bone.

• Compact bone is arranged in units called osteons or Haversian systems (Figure 6.3a). 

• Osteons contain blood vessels, lymphatic vessels, nerves, and osteocytes along with the calcified matrix. 

• Osteons are aligned in the same direction along lines of stress. These lines can slowly change as the stresses on  the bone changes.

• Looks like solid hard layer of bone

• Makes up the shaft of long bones and the external layer of all bones  

• Resists stresses produced by weight and movement

Histology:

• Osteon is concentric rings (lamellae) of calcified matrix surrounding a vertically oriented blood vessel  

• Osteocytes are found in spaces called lacunae

• Osteocytes communicate through canaliculi filled with extracellular fluid that connect one cell to the next cell 

• Interstitial lamellae represent older osteons that have been partially removed during tissue remodeling

7. Spongy bone.

• Spongy (cancellous) bone does not contain osteons. It consists of trabeculae surrounding many red marrow filled spaces (Figure 6.3b). 

• It forms most of the structure of short, flat, and irregular bones, and the epiphyses of long bones. 

• Spongy bone tissue is light and supports and protects the red bone marrow.

Trabeculae:

• Latticework of thin plates of bone called trabeculae oriented along lines of stress 

• Spaces in between these struts are filled with red marrow where blood cells develop 

• Found in ends of long bones and inside flat bones such as the hipbones, sternum, sides of skull, and ribs.

8. Blood and nerve supply bone.

• Periosteal arteries

– supply periosteum

• Nutrient arteries

– enter through nutrient foramen 

– supplies compact bone of diaphysis & red marrow 

• Metaphyseal & epiphyseal aa.

– supply red marrow & bone tissue of epiphyses

9. Bone growth.

• To understand how a bone grows in length, one needs to know details of the epiphyseal or growth plate (Figure 6.7). 

• The epiphyseal plate consists of four zones: (Figure 6.7b)

– zone of resting cartilage,

– zone of proliferation cartilage,

– zone of hypertrophic cartilage, and

– zone of calcified cartilage The activity of the epiphyseal plate is the only means by which the diaphysis can increase in length. 

• When the epiphyseal plate closes, is replaced by bone, the epiphyseal line appears and indicates the bone has completed its growth in length.

Zone:

• Zone of resting cartilage

– anchors growth plate to bone

• Zone of proliferating cartilage

– rapid cell division (stacked coins) 

• Zone of hypertrophic cartilage

– cells enlarged & remain in columns 

• Zone of calcified cartilage

– thin zone, cells mostly dead since matrix calcified 

– osteoclasts removing matrix

– osteoblasts & capillaries move in to create bone over calcified  cartilage

Length: 

• Epiphyseal plate or cartilage growth plate 

– cartilage cells are produced by mitosis on epiphyseal side of plate 

– cartilage cells are destroyed and replaced by bone on diaphyseal side of plate 

• Between ages 18 to 25, epiphyseal plates close. 

– cartilage cells stop dividing and bone replaces the cartilage  (epiphyseal line) 

• Growth in length stops at age 25

Thickness:

• Bone can grow in thickness or diameter only by appositional

growth (Figure 6.8).

• The steps in thes process are:

– Periosteal cells differentiate into osteoblasts which secrete collagen fibers and organic molecules to form the matrix. 

– Ridges fuse and the periosteum becomes the endosteum. 

– New concentric lamellae are formed.

– Osetoblasts under the peritsteum form new circumferential lamellae.

Width:

• Only by appositional growth at the bone’s surface

• Periosteal cells differentiate into osteoblasts and form bony ridges and then a tunnel around periosteal blood vessel. 

• Concentric lamellae fill in the tunnel to form an osteon.

10. Factors affecting bone growth.

• Nutrition

– adequate levels of minerals and vitamins

• calcium and phosphorus for bone growth

• vitamin C for collagen formation

• vitamins K and B12 for protein synthesis

• Sufficient levels of specific hormones

– during childhood need insulinlike growth factor

• promotes cell division at epiphyseal plate

• need hGH (growth), thyroid (T3 &T4) and insulin

– sex steroids at puberty

– At puberty the sex hormones, estrogen and testosterone, stimulate sudden growth and modifications of the skeleton to create the male and female forms

11. Fracture and repair of bone.

A fracture is any break in a bone.

• Fracture repair (Figure 6.10)involves formation of a clot called a fracture hematoma, organization of the fracture  hematoma into granulation tissue called a procallus (subsequently transformed into a fibrocartilaginous [soft]  callus), conversion of the fibrocartilaginous callus into the  spongy bone of a bony (hard) callus, and, finally,  remodeling of the callus to nearly original form

• Healing is faster in bone than in cartilage due to lack of blood  vessels in cartilage 

• Healing of bone is still slow process due to vessel damage 

• Clinical treatment

– closed reduction = restore pieces to normal position by  manipulation 

– open reduction = realignment during surgery

Fractures:

• Named for shape or position of fracture line

• Common types of fracture

– greenstick -- partial fracture

– impacted -- one side of fracture driven into the interior of other side

• Named for shape or position of fracture line

• Common types of fracture

– closed -- no break in skin

– open fracture --skin broken

– comminuted -- broken ends of bones are fragmented

• Named for shape or position of fracture line

• Common types of fracture

– Pott’s -- distal fibular fracture

– Colles’s -- distal radial fracture

– stress fracture -- microscopic fissures from repeated strenuous activities

Repair of a fracture:

• Formation of fracture hematoma

– damaged blood vessels produce clot in 6-8 hours, bone cells die

– inflammation brings in phagocytic cells for clean-up duty

– new capillaries grow into damaged area

• Formation of fibrocartilagenous callus formation

– fibroblasts invade the procallus & lay down collagen fibers

– chondroblasts produce fibrocartilage to span the broken ends of the 

• Formation of bony callus

– osteoblasts secrete spongy bone that joins 2 broken ends of  bone 

– lasts 3-4 months

• Bone remodeling

– compact bone replaces the spongy in the bony callus

– surface is remodeled back to normal shape bone