Physiology exam

exam

Types of tissues

Epithelial - line internal/external passages

Connective - fill internal spaces

Muscle - contracts for movement

Neural - carries information via impulses

Functions and characteristics of epithelial tissues

• Cell polarity

• Stratified epithelial tissue

Types of glands

Endocrine glands

Exocrine glands

Different types of cells

Lymphocyte

Glial

Muscle fibres

Functions of cells

Protection

Permeability

Sensation

Secretions

Apical and Basal

Apical - top of tissue

Basal - bottom of tissue

Cilia and microvili

Cilia - hair like - beat to move mucus

Microvilli - increase surface area

Cell adhesion molecules

Connect large areas of plasma cells

Connect basal surface with basement membrane

Cell junctions

Gap junctions - communication between cells

Tight junctions - prevent movement between cells

Desosomes - resist twisting and stretching, strong connections, found in superficial layer of skin

Simple squamous epithelium

-lines heart

-lines kidneys

-high to low conc diffusion

-located in alveoli - exchange of co2 and o2

Stratified squamous epithelium

• Exposed to nasties on skin

• Line mouth, throat, oesophagus, rectum, anus, vagina

• Protects underlying regions of body

Simple cuboidal epithelium

• Glands, ducts, regions, of kidneys

• Limited protection, secretion, absorption

• Lines ducts of sweat glands

Transitional epithelium

• Located in bladder, renal, pelvis, urerters

• Permits stretching without damage

Simple columnar

• line stomach, intestine, gall bladder, kidneys,

• protects, secretes, absorbs

• microvilli - increases surface area

Pseudostratified columnar

• Nasal cavity, trachea, bronchi, male reproductive tract

• Beat cilia to get rid of mucus

• protect

• secrete

• absorb

Stratified columnar

• Pharynx, epiglottis, anus, mammary glands, salivary gland, urethra

• Protects

Exocrine glands

Multicellular glands - found in pockets, secrete into ducts before reaching epithelial surface

Glandular secretion

Merocrine secretion - sweat

Apocrine - mammary glands - produce milk

Holocrine - sebaceous gland - burst - produce oil in hair and legs

Types of secretions from glands

Serous - watery

Mucous - secrete mucins - form mucus

Mixed exocrine glands - serious an dmucous

Connective tissue function

• Connect epithelium to body

• Provides structure

• Store energy

• transport blood

Connective tissue structure

• Extracellular matrix - strong and rigid structure

• Made of collagen fibres and fibrocyte nuclei

Connective tissue proper cells

Fibroblasts - most abundant, secrete proteins

Fibrocytes - second most abundant, maintain fibres

Cells

Adipocytes - fat cells

Mesenchymal cells - divide when cells are damaged

Melanocytes - melanin - brown pigment

Macrophages engulf bacteria and dying cells

Mast cells - release histamine, tissue repair

Lymphocyte - immune system

Fibres

Collagen - most common in connective tissue, flexible, long, straight

Reticular - long and interwoven - allow for strength and flexibility

Elastic - made of elastin, allow stretch and return

Ground substance

• Proteoglycans

• Glycoproteins

• Fills space between cells and surrounds fibres

Loose connective tissue

• The packing of materials of the body - fills spaces between organs

• Cushion and stabilise cells in organs

• Support epithelia

• three types - areolar, adipose, reticular

Areolar

• Least specialised

• loosely organised

• ground substance

• elastic fibres

• holds blood vessels and capillary beds

Adipose

Contains adipocytes - fat cells

does not divide

expands/shrinks to store and release fat

Reticular

provides support

3d network

complex

found in spleen, liver, bone marrow

Dense connective tissue

tightly packed

lots of collagen and elastic fibres

elastic tissue

contains regular and irregular dense tissue

Dense regular tissue

tightly packed

tendons - muscle to bone

ligaments - bone to bone

aponeuroses - attaches in sheets

Dense irregular

interwoven network of collagen

layered

around cartilage

around bones

form capsules around organs

strengthens and supports

Elastic tissue

made of elastic fibres

allows tissue to expand and recoil

Fasciae

connective tissue layers that support trunk organs

superficial fascia - layer of alveolar and adipose underlying the skin

deep fascia - dense regular connective tissue - found in capsules

Subserous fascia - lies between deep fascia and serous membranes

Fluid connective tissue

blood and lymph

watery matrix of dissolved proteins

contains cells

formed elements of blood

red blood cells - erythrocytes

white blood cells - leukocytes

platelets

lymph

extracellular fluid

collected from interstitial space

monitored by immune system

transported by lymphatic system

supportive connective tissue

framework that supports body

cartilage - gel type substance supports body

chondrocytes

cartilage

hyaline

elastic

fibrocartilage

Bone

calcified

strong

osteocytes - mature bone

4 membranes

1. mucous - line passages

2. serous - line cavities, thin, strong (pleura - lungs, peritoneum - abdominal organs, pericardium - heart)

3. cutaneous - skin, thick, waterproof, dry

4. synovial - line joint cavities, lubricant, lack true epithelium

3 types of muscle

skeletal - voluntary

cardiac - involuntary

smooth - involuntary

Sensory neurons

delivers info from sensory receptors to CNS

Motor neurons

deliver info about movement from CNS to effector

Interneurons

form connections with other neurons

Neurons

stem cells in adults that are usually inactive

Neuroglia

important for survival and function of neurons

50% of neural tissue

in CNS and PNS

Neuroglia of CNS

astrocytes - abundant, maintain blood brain barrier, form scar tissue

ependymal - line spinal cord, produce, secret, and monitor cerebrospinal fluid

oligodendrocytes -proceeses mylein sheath around axons

miceoglia - small, migrate through neural tissue, clean up cell debris and waste

Neuroglia of PNS

Satellite - regulate environment around neurons

Schwann - wrap around and insulate axons

Myelin - increase speed of information along axons

Neurotranmission

transmit info across synapse

membrane potential

separation of positive and negative charged molecules

resting membrane is -70mV

intracellular - negative

extracellular - positive

movement of sodium from outside to inside of cell 0

membrane potential and pumps

potassium channels - high to low conc

sodium channels - movement of sodium ions - high to low conc

protein pump - pumps out sodium from inside to outside of cell

lots of ions in a cell can cause it to have a negative charge

Passive channels - leak channel

ions move freely from inside to outside of cells

sodium and potassium channels maintains resting membrane potential

Active channels - gated channel

open and closes in response to certain stimuli

at resting - most gated channels are closed

open active channels can change membrane potential

3 types of active gated channels

chemically gated - chemical binds to cell and lets sodium in

voltage gated - sodium enters through passive channel, threshold is reached, sodium enters via diffusion, once cell reaches 30mV gate closes, sodium cant enter.

mechanically gated - pressure makes structure of gate change, sodium enters cell, membrane potential changes and pressure removed to stop sodium from entering.

Graded potential

small, local, temporary change in membrane potential

if membrane potential is less than -55mv/-60mv an action potential is discharged

4 phases of action potential

resting - graded potentials reaches threshold, voltage gated sodium channels open

depolarisation - inside cell becomes positive (+30) - sodium moves into cell

repolarisation - inside cell becomes negative (-70) - sodium inactivated, potassium channels open and move out of cell.

Hyperpolarisation - inside cell becomes more negative (-90), potassium channels close

resting - resting membrane potential is restored

Neurotransmission

An action potential passes from one neuron (presynaptic) to a second neuron (postsynaptic) at a synapse via neurotransmitters

Two types of synapses

electrical - direct physical contact between two cells - info transmitted quickly and efficiently

chemical - cells are not in contact - communication between neurons

How many bones in the human body

206

Long bone structure - femur

articular cartilage

epiphysis

cancellous bone

compact bone

medullary cavity contains yellow marrow

periosteum

endosteum

epiphyseal lines

secondary epiphysis

diaphysis

Cancellous/spongy bone

osteocytes - inside bone

osteoblasts - outside bone

osteoclasts - under bone

Endochondral ossification

1. cartilage is made

2. growth of cartilage

3. primary ossification centre - nutrient artery in centre of cartilage - bone mineral matrix covers cartilage forming spongy bone

4. medullary cavity - bone mineral is reshaped and remodelled

5. secondary ossification centre - blood vessels enter epiphyses - spongy bone formed

6. formation of cartilage on joints

Growth of long bones

new cartilage in epiphyseal plate - pushes epiphysis higher

cartilage underneath turns into spongy bone

cortex on outside turns into hard bone

cartilage and chondrocytes disappear - left with epiphyseal line

Growth of flat bones - intramembranous ossifcation

example - skull, collar bone

directly form from osteoblasts

dont have a growth plate

fibroblasts differentiate into osteoblasts and mineralise

Bone structure

organic collagen matrix - 10% - provides elasticity

mineral - 65%

water - 25%

traces of magnesium, sodium, and bicarbonate

osteoblasts

form bone

osteoclasts

destroy bone

osteocytes

mature bone

bone remodelling

occurs at low gravity - meaning less strain on bone

replace 10% of skeleton each year

remodelling is a constant and coordinated process

remodelling bone is necessary

to repair and heal micro fractures

to adapt the skeleton to the demands of the structure

to supply calcium and phosphate

repairing microfractures

osteocytes sense change

osteoclasts activated

osteoclasts break down bone

osteoblasts arrive and form bone

remodelling complete

Hormones controlling bone metabolism

parathyroid hormone - released in response to low calcium - triggers bone resorption

Calcitriol - released in response to high PTH - triggers bone resorption

vitamin

promotes calcium and phosphorus absorption to supply growing skeleton

regulate osteoblasts and osteoclasts

Osteoporosis

holes in bone become larger

imbalance of bone resorption and bone formation

holes are filled with fat/bone marrow - bone density decreases

Roles of muscles

body movement

maintenance of posture

respiration

produce body heat

communication

control blood flow

muscle structure

muscle - muscle fascicle

muscle fascicle - epimysium

muscle fascicle - perimysium

muscle fibre - endomysium

sarcolemma

muscle fibre shortening

THIN ACTIN

THICK MYOSIN

ACTIN SURROUND MYOSIN - contraction

Relaxation of muscle - less overlap of fliaments - muscle elongates

Role of calcium

muscle contraction

expose myosin

released on myofibril

skeletal muscle contraction

isotonic contraction - muscle length shortens

isometric contraction - no change in muscle length

effects of exercise on bone

1. improve bone mineral density

2. early life exercise important to achieve peak BMD