CELL PHYSIO, HOMEOSTASIS, CONNECTIVE TISSUE, BONE PHYSIO, INTEGUMENTARY SYSTEM

WEEK 2

homeostasis

maintenance of (nearly) constant conditions in internal environment (ECF)

2 major compartments of body

intracellular, extracellular fluid

what divides ICF and ECF?

cell membrane

what divides plasma and interstitial fluid?

capillary membrane (PROTEINS ARE IMPERMEABLE TO CAPILLARY MEMBRANE)

abundant cations in ICF

potassium (K+)

secondary: magnesium (Mg+)

abundant cation in ECF

sodium (Na+)

anions in ICF

organic phosphate, proteins

ECF volume formula

interstitial fluid + plasma

equilibrium vs. steady state

equilibrium is a point of balance without activity, steady state uses activity (mechanisms) to survive

relationship between regulated variable and set point

set point acts as goal, regulated variable depends on type of feedback loop

control system

regulates function to maintain set point e.g. nervous system, endocrine

3 types of control systems

local, reflex, adaptive

local control definition

response occurs near problem without involving brain/distant organs (e.g. blood clotting), does not involve hormone/nerves

long distance control definition

response controlled at integrating center, response affects entire system, involves hormone/nerves

reflex control

automatic response with reflex arc pathway

response loop

initiates pathway

feedback loop

manages, checks pathway

negative feedback

counter variable to maintain homeostasis

positive feedback

more of variable to maintain homeostasis

feedforward definition

body anticipates change, starts response before change happens

negative feedback examples

temperature, pH, glucose, osmoregulation

positive feedback examples

lactating, birth, ovulation, blood clot

feedforward examples

salivating before food, increased heartrate from epinephrine

what happens to set points in biological rhythms + e.g.

changes based on time e.g. estrogen, progesterone levels in menstrual cycle

chromatin function

protein + DNA, compact to increase SA:V, condenses/supercoils to become chromosome during cell division

adaptive control mechanism definition

change in response over time based on repetition/exposure

nuclear envelope definition

double membrane around nucleus

nuclear pores

passage of certain molecules e.g. mRNA strand

nucleolus

rRNA and ribosome synthesis

golgi apparatus

modifies, packages proteins/lipids for storage/transport

smooth ER

INTRACELLULAR USE

1. lipid, carbs synthesis

2. stores calcium (SR specific)

3. detoxifies waste

rough ER

makes proteins

peroxisome

1. detoxifies harmful substances

2. breaks down:

   1. hydrogen peroxide

   2. fatty acids

   3. lipids

   4. AA

cell cytoskeleton

protein filaments microtubules, microfilaments

fibroblast cells

secretes fibers

adipocyte cells

makes and stores fat

chondroblast cells

makes/builds cartilage

osteoblast cells

builds bone by releasing osteoid (unmineralized, organic bone matrix)

hematopoietic cells

makes blood cell

mast cells

initiates inlfammatory response

macrophage

engulfs pathogens

composition of cytoskeleton

microfilament (actin), filaments, microtubules

cytoskeleton function

cell shape and support, transport

extracellular matrix function and definition

cell attachment, environment surrounding cells

4 types of bone cells

osteoprogenitor, osteoblast, osteocytes, osteoclast

osteocyte

1. mature bone cells caught in matrix (used to be osteoblast but got trapped)

2. senses stress

3. manages bone remodelling

osteoclast

breaks down bone tissue to release calcium to blood/build new bone

compact bone

1. ‘CORTICAL’ BONE

2. dense outer layer

3. strength & protection

spongy bone

1. ‘CANCELLOUS’ BONE

2. contains trabecula (honeycomb-like) network

3. shock absorption

4. holes in trabecula contain bone marrow

describe bone growth of width

occurs via appositional growth (osteoblast adds bone tissue to surface)

describe bone growth of articular cartilage

growth maintains joint function while the epiphyseal plate is still active

categories of bone density, categories of bone tissue maturity

compact/spongy, lamellar/woven

factors affecting bone growth

nutrition, hormones

ground substance

material between cells and fibers in CT (for diffusion)

3 types of protein fibers

collagen, elastic, reticular

collagen fiber characteristics

strong, flexible fibrous structure

elastic fiber characteristics

stretches, recoils

reticular fiber characteristics

supports soft organs

mechanical stress

exercises increase bone density by stimulating osteoblasts

factors of CT

1. cell

2. structure

3. vascularity

4. matrix

mnemonic for layers of epidermis

CAN LEE KNOW GET SUM BOOBS

keratinocyte function

makes keratin

stratum basale

1. site of cell division, one layer of cuboidal/columnar cells, most active keratinocytes 

2. during cell division, one daughter cell remains stem cell to divide

3. the other daughter cell pushed to surface

stratum spinosum

cells flatten, more keratin is synthesized (but not done)

stratum granulosum

1. cells fill with keratin (final site of living keratinocytes)

2. cells parallel to surface of skin

3. keratohyalin present (protein binding keratin fibers together to form waterproof barrier of skin)

stratum lucidum

clear layer, only in thick skin

stratum corneum

outermost layer, dead keratinocytes

thin vs. thick skin

thick includes stratum lucidum, hairless. thin lacks lucidum, contains sebaceous/sudoriferous gland

6 contents of dermis

1. fibroblast

2. macrophage

3. adipocytes

4. smooth muscle

5. glands

6. lymphatic vessel

7. nerve ending

subcutaneous tissue

below dermis, contains adipose tissue, aka hypodermis, NOT PART OF SKIN

root hair

part embedded to skin

hair shaft

projects from skin

hair follicle

surrounds root, source of new epithelial tissue

hair bulb

base of follicle, contains hair matrix for growth

arrector pili muscle

smooth muscle attached to hair follicle, stands upright when contracted

eccrine gland

produces sweat

apocrine gland

found in axillary and genitals, released during stress and arousal

ceruminous glands

produces earwax

nail plate

visible hard part

nail bed

skin beneath nail plate

lunula

white base of nail

nail cuticle

fold of epidermis at base of nail

nail root

site of cell division

intramembraneous ossification process

bone forms in fibrous connective tissue

1. osteoblast secretes organic (unmineralized) ECM called osteoid

2. mineralization: calcium, mineral salts deposited

3. ECM calcifies (hardens) matrix

4. ECM becomes spongy bone trabeculae, fuses to form spongy bone

5. mesenchyme condenses into periosteum

endochondral ossification process

bone replaces cartilage

1. CARTILAGE MODEL: mesenchymal cells differentiate to chondroblast 

2. cartilage model grows via cell division of chondrocytes

3. primary ossification center forms in diaphysis, replacing cartilage model

4. osteoclast breaks down bone to form medullary cavity

5. secondary ossification occurs in epiphysis

6. epiphyseal plate and articular cartilage form

structure of nucleus

1. nuclear envelope

2. nuclear pores

3. nucleolus

4. chromatin

purpose of connective tissue

1. connect (connective)

2. support and move (bone)

3. store

4. cushion

5. transport

6. protect

7 specialized cells in CT

1. fibroblast

2. adipocyte

3. chondroblast

4. osteoblast

5. hematopoietic

6. macrophage

7. mast cell

3 components of extracellular matrix (ECM)

1. ground substance

2. protein fibres

3. interstitial fluid

functions of cell membrane

1. separate cell from cytoplasm, ICF from ECF

2. transport of materials

3. reception of chemical signals

4. anchorage

5. cell recognition

6. intercellular joinings

7. enzymatic activity

8. maintain chemical gradient

describe bone growth of length

1. occurs at epiphyseal plate via endochondral ossification

2. bone replaces cartilage

purpose of bone remodelling

1. repair damage/reshape

2. release calcium to blood

functions of the Integumentary System

1. Protection (chemical, physical, biological barriers)

2. Sensation (sensory receptors)

3. Temperature Regulation

4. Vitamin D Production

5. Excretion (of wastes via sweat)

5 layers of epidermis

stratum: 

1. corneum

2. lucidum

3. granulosum

4. spinosum

5. basale

structure of hair

1. root

2. shaft

3. follicle

4. bulb

5. arrector pili muscle

types of sudoriferous sweat glands

1. eccrine

2. apocrine

5 parts of nail

1. plate

2. bed

3. lunula

4. cuticle

5. root

intracellular fluid 

1. inside cells

2. site of metabolic reactions

subcategories of extracellular fluid (ECF)

fluid inside vs. outside vessels

1. inside - plasma

2. outside - interstitial fluid (ultrafiltrated ver. of plasma) 

contents of plasma

1. water

2. blood cells (suspended, floating in plasma, but not dissolved in it)

3. glucose

4. AA

5. hormones

6. plasma proteins

7. lipoproteins with lipids

8. phospholipid

9. fats