skin and accessory structures.

(hair, nails, glands, muscles, & nerves)

Function of the integumentary system 

(3)

1) barrier b/t body's external and internal environment

2) body temp. regulation

3) sensation of ex. environment

The skin is an organ & is the largest in the entire body!

What are the 2 layers of the skin?

Epidermis: lining or covering membrane)

Dermis: connective tissue part below the epidermis derived from the mesoderm

What is keratin?

keratin= cytoskeleton= intermediate filaments= stratum corneum

Tough fibrous protein that forms an extracellular matrix that protects the body from heat, microbes, infection, & chemicals. 

keratinocytes:make up 90% of epi. ; produce keratin & protect

melanocytes: produce pigment melanin Protect the DNA FROM UV RADIATION.

Langerhan cells: immune cells 

Merkel cells: light touch sensation

5 layes of the epidermis

(from deepest to most surface)

Stratum Basale

Stratum Spinosum

Stratum Granulosum

Stratum Lucidum

Stratum Corneum

Stratum Spinosum

(thickest layer)

- stratified layer of plump keratinocytes 8-10 cells thick

- contains Langerhans cells & melanocytes (pigment & dendrites)

- strat. layer of keratinocytes 3-5 cells thick

- cells in layer are dying by a process of programmed cell death (apoptosis)

- distinguished by dark staining granules in the cytoplasm

- space is filled with lipid rich material that functions as a water repellent & sealant - (secreting oils)

Stratum Lucidum

-(not in all skin- present in finger tips, palms, and soles that are areas of high friction)

-helps reduce abrasions

- contains cell membranes, keratin, and lipids

- the keratin extracellular matrix which is derived from intermediate filaments of dead cells

- dead cells of this layer are constantly shed and most be replaced by cells from the deeper layers

Dermis

(2 layers)

1)Papillary Region- under the epidermis (responsible for fingerprints)

2) Reticular Region- next to hyperdermis

- contain blood vessels: b/c help maintian body temp.

-sensory nerves for - light touch = Merkel

• touch called Meissner corpuscles
• temp, pain, tickling, & itching = free nerve endings
• pressure = Paccinian corpuscles

- collagen fiber bundles arranged in a dense irreg. array w/ elastic fibers interspersed to provide strength & elasticity

- contains accessory organs: adipose cells, hair follicles, nerves, oil glands, & sweat glands

Accessory Structures of the skin

(hair, glands, & nails)

-Protection from UV radiation, & foreign particles in eyes and nostrils.

- Aid the sensation of light touch

- root with bulb: extends from dermis to epidermis

- base of the bulb contains papilla where blood vessels enter the hair

- the matrix, contains stem cells of the stratum basale which undergo cell / to supply new cells for hair growth

- hair shaft which begins w/ a root in the bulb & goes through the epi. & extends beyond the surface

- follicle invagination of epi. surrounding the bulb

1) Sabaceous glands (oil glands)

2) apocrine sweat glands

3) smooth muscle (erector pili)

4) nerve endings (hair root plexuses) which sense shaft movement (touch)

Exocrine glands of the skin:

1. Sebaceous (oil)
2. Sudoriferous (sweat)
3. Ceruminous
4. Mammary

1. Sebaceous (oil)- an oil which moistens hair & skin, prevents water evaporation, & inhibits bacteria growth
2. Sudoriferous (sweat)- 2 types: (1) Eccrine glands- open a pore  on the surface of the skin. Function: lower body temp. (2) Apocrine Sweat glands- open on a hair follicle. Emotional highs and lows. (Associate through emotional states: fear, love, & embarrassment) hormonal = puberty enduced
3. Ceruminous- produce wax
4. Mammary- secrete milk (has proteins added to it)

- plates of tightly packed hard  keratinized epidermal cells

- "plate of hair"

- nails hard b/c of how keratin is composed

1. Thermoregulation- (temp. regulation)
2. Protection- barrier function
3. Sensation- touch, pressure, vibration, itching, temperature, & pain
4. Excretion & Absorption-  passage of substances into & out of the body including water, heat, & small amounts of salts & wastes. 
5. Synthesis of Vitamin D = calcitrol; - UV rays convert a cholesterol derivative in skin which is modified first in liver then in kidney to its active form, calcitrol, for calcium homeostatis.

1. support- provide a framework for the rest of the body
2. protection- of vital organs (flat bone - sternum, ribs, skull, hips)
3. movement- point of attachment for muscles via tendons
4. mineral homeostasis-calcium crucial to the body
5. blood cell production (hemopoiesis)- occurs in red bone marrow & produces both red and white cells
6. triglyceride storage (fat)- occurs in yellow bone marrow which consists mainly of adipocytes; "compact bone"

Types of Bone

(5)

1. Long bone: longer than they are wide; "digits" & function as weight bearing support structures (ex= femur & humerus)
2. Short bone: cube shaped; ex= found in wrist & ankle
3. Flat bone: thin flat bones functions as protection; ex= in sternum, ribs, & scapula
4. Irregular bone: complicated shaped bones; ex= shpenoid, ethmoid, vertebrae, & hip bones
5. Sesmoid bone:bones embedded in tendons; function to stabilize tendon; an ex = the patella

- Diaphysis: main section;  yellow marrow

- Epiphysis:ends of the bone; core of spongy bone containing red marrow-->hemopoises

- Metaphyses: found b/t the diaphysis & epiphysis; contains the epiphyseal plate = elongation center & eventually fuses (know if a bone has been through puberty); core of spongy bone containing red marrow

- Articular cartilage: forming a joint; joint surface

- Periosteum: around the bone (outer CT layer)

- Medullary or Marrow Cavity: space within the diaphysis; yellow marrow

- Endosteum: inner CT lining; contains bone forming cells

Cells

*osteogenic cells>

osteoblasts>osteocytes>

osteoclasts are unrelated

1. osteogenic cells= stem cells
2. osteoblasts- "bone building cells" = build matrix; synthesize & secrete collagen, function in mineral deposition & matrix hardening for calcification (mineralization)
3. osteocytes: "mature bone cells"; maintains bones structure

1. osteoclasts: "bone destroyers"; located in endosteum w/ spongy bone; functions in resorption, the breakdown of bone matrix; releases Ca2+; replace old bones; liberate calcium

Compact bone

Spongy bone

Compact Bone

C- contains few spaces in the bone matrix = hard bone, forms external layer of all bones, provides protection and support, the structural unit of compact bone = osteon--> structural units:

- concentric lamellae:rings (minerals/ collagen)

-central canal: contain blood/ lymph vessels

-perforating canal: contain central canal to periostium/ endosteum via blood/ lymph vessels

-lacunae: osteocytes/ cavity b/t lamellae

-canaliculi: ECF (extracellular fluid) + cytoplasmic processes of osteocytes

-bone growth is stimulated by growth hormone & insulin like growth factors (IGF) & requires insulin & TSH

- at puberty sex steroids estrogen & androgens accelerate bone growth--> growth spurt

***estrogen stops bone growth.

low dose- slower stop

        high dose- faster stop

- Hematoma formation: clot around break

- Fibocartilaginous Callus Formation: clot replaced w/ collagen & cartilage

- Bony Callus Formation: fibrocartilage--> spongy bone

- Bone Remodeling: compact bone to surfaces

- occurs when bone breakdown & renewal are balanced

- constant remodeling of bone allows bone adaptation to increased of decreased stress (gravity and muscle pull) by realigning lamellae & changing thickness.

- use it or loose it ---> if bones are not in a weight bearing situation for an extended period, bone mass is lost

- higher outside than inside of a cell

- allows it to be a triggor to other activity throughout the body

** Ca2+ charge allows it to want to come in

**Liver, skin, kidneys (and sometimes your gut) helpt Vit. D. --> calcitrol (an active protein which increase blood calcium through the action on both kidneys & small intestine, main main action = enable the absorption of Ca 2+ in the small intestine (enables Ca2+ to be transported out of the intestine lumen & into the blood)

Elongation (height) : stops b/c estrogen

Appositional: <---> (width); ability to change throughout life

Intramembraneous ossification-

flat bone; no cartilage

Endochondral ossification- 

long bone; cartilage

S- contains extensive space b/t bone matrix, matrix is composed of lamellae arranged in columns called trabeculae (structural unit of spongy bone), spaces b/t trabeculae containred marrow (hemopoiesis),

-spongy bone is found in: short, flat, & irregular shaped bones; epiphysis of long bones; & around the medullary cavity of long bones

1. Water
2. Minerals - what makes the bones hard(er)
3. Collagen fiber - (what determines the amount of flexibility in bones)

** Want bones harder: increase mineral; decrease collagen fibers

**Want bones more flexible: decrease mineral; increase collagen fibers

- Whole: CT- epimysium (which connects to periostrum

- Fascicle: CT- perimysium

- Fiber: CT- endomysium

1 muscle cell w/ many nuclei from fused membrane

**ALL RUN FROM ORIGIN TO INSERTION (LENGTH)

Myofibril

Myofibril- chain of sarcomeres

located: inside fibers = single cell

titen = responsible for elastic recoil ***know the drawings!

**when contracts- 2 lines move together & overlap (in actin & myosin)

*only titen decrease in size!

• carry AP into cell
• wraps around SR (sarcoplasmic reticulum)
• barrier b/t what goes into cell
• membrane modification

• Ca2+ reservoir in cells
• Ca2+ pumps
• Voltage gated Ca2+ channels

• Mitochondria--> ATP production (energy maker)
• Myoglobin--> stores O2 in muscle cells
• Glycogen Granules--> stored glucose

Sources of Energy 

for Muscle Cells

• Creatine Phosphate: immediate energy/ ATP can't be stored
• Anaerobic Glycolysis: lactic acid build up (very insufficient & can only be good for 30-60 seconds)    "sprinters"
• Aerobic Respiration: cardiovascular system beginning to work (most efficient way to generate ATP & is capable of fueling long term activity) "long distance runners"

Sources: elastic recoil (comes from titen) ; actin/ myosin

Determine muscle force:

1. length of sarcomere: the longer it is, the greater force will be applied (stretch recoil) & (length of actin/ myosin overlap)
2. # of motor units: single motor neuron that synapses w/ all fibers from strength
3. AP frequencies: how much Ca2+ released into fiber          (* causing cramps, just to much Ca2+ to relax muscle)

Stop Contraction

"Exhaustion"

ACh--> 

- stop Action Potential & get rid of whats left in synapse.

- closes Voltage gates so Ca2+ can be reabsorbed & release stops

***Removal of ACh is done through: endocytosis; diffusion; enzymatic breakdown

• sarcomeres shorter, muscle contract, & object doesn't move        - moving a wall but it won't move even though muscles are working correctly

• moving an object, sarcomeres shorten and muscles contract

concentric: moves object

eccentric: (-) reps

- filtration is greater than reabsorbtion

-nodes = cleans fluid

-spleen = cleans blood

1. tough capsule
2. capsule
3. affarent & efferent (large volume vs. small volume)

- in thyroid: remove t-cells that would attack self

->getting T-cells to recognize to recognize self and foreign antigens

1. nodes- filters nymph (macrophages)
2. spleen- filters blood; lymphocyte & immune response
3. Thymus- does NOT filter matures T-cells
4. MALT- mucous linements (gut, Urine tract, Reproductive tract, digestive tract, appendix, tonsils)

Immunity

(Non-specific)

--->Innate- an immediate response "street sweepers" system relying on:

- NK cells

- Phagocytes

- Barriers

- Acid

- Mucous-->biggest 

- Extracellular matrix always there!

Specific 

(Immunity)

-secondary response system relying on antibodies & lymphocytes (T&B lymph) that attack specific foreign substances "rise to the occasion"

adaptive defenses--> humoral immunity (B Cells : bone marrow)

cellular immunity (T Cells : Thymus)

- Fever = systemic elevation of temperature

-Inflammation = localized

Symptons = redness, heat, swelling, & pain (Vasodilation- pressure pushes on nerve endings)

Blood Volume = increases in diameter

Increases Blood Flow

1. Emigration
2. Chemotaxis
3. Adherence
4. Injestion
5. Digestion
6. Exocytosis