Human Physiology Exam 2 Review

3 types of muscles

skeletal, cardiac, smooth

skeletal muscle histology

large, multinucleate, striated, somatic control

cardiac muscle histology

middle sized, uni-nucleate, striated, branched, ANS control

smooth muscle histology

small, uni-nucleate, non-striated, ANS control

muscle cell

muscle fiber

cell membrane

sarcolemma

cytoplasm

sarcoplasm

ER

sarcoplasmic reticulum

sarcomete

smallest unit of contractile muscle fiber

T-tubule

extension of sarcolemma that brings AP into muscle fiber

sarcoplasmic reticulum stores

calcium

actin is ___ filament

thin

myosin is ___ filament

thick

what causes sarcomere to shorten?

actin and myosin sliding together

titin

responsible for passive tension in muscle and recoil

myosin heads have

ATPases

hinge region

part of myosin that allows it to pivot from 45 to 90 degrees

Z disk

actin filaments attached

M line

myosin anchor point

I band

only actin

H zone

only myosin

A band

anywhere that has myosin

during contraction ____ get pulled toward each other

Z lines

do the length of myosin and actin change?

no, only overlap

during contraction the ___ and ___ shorten while the ___ stays the same

I band, H zone, A band

Contraction cycle step 1

actin and myosin bind in rigor state, no ATP

Contraction cycle step 2

ATP binds to myosin, myosin dissociates from actin

Contraction cycle step 3

ATPase hydrolyzes ATP into ADP and Pi

Contraction cycle step 4

Myosin swings and weakly binds to new actin

Contraction cycle step 5

power-stroke, Pi release and myosin pulls actin towards it

Contraction cycle step 6

ADP releases, back to rigor state

skeletal muscle contraction calcium step 1

calcium released from sarcoplasmic reticulum

skeletal muscle contraction calcium step 2

calcium binds to troponin

skeletal muscle contraction calcium step 3

calcium-troponin moves tropomyosin away from actin-myosin binding site

skeletal muscle contraction calcium step 4

calcium ATPase pumps calcium back into sarcoplasmic reticulum

skeletal muscle contraction calcium step 5

calcium and troponin unbind and tropomyosin returns to original position

skeletal muscle cell depolarization

somatic motor neuron releases Ach and sodium entry causes action potential

is there a delay between action potential firing and contraction?

yes

motor unit

motor neuron and the muscle fibers it innervates

one motor neuron can innervate ___ muscle fiber(s)

many

each muscle fiber is innervated by ___ motor neuron(s)

only one

sources of energy for contraction (4)

free ATP, creatine, glycolysis, oxidative phosphorylation

free ATP produces ___

8 twitches

creatine phosphate makes enough ATP to last for

15 seconds

glycolysis ___ require oxygen and produces ___ ATP

does not, 2

oxidative phosphorylation ___ require oxygen and produces ___ ATP

does, 28-30

levels of contraction (3)

twitch, unfused tetanus, fused tetanus

muscle tension increases by

increasing frequency of stimulation

isotonic

muscle moves load and shortens

isometric

muscle tension and load balance, no change in length

lengthening

load greater than muscle tension, muscle lengthens despite contraction

lengthening (elastic elements)

sarcomere contracts but elastic elements stretch more

types of muscle contraction (3)

slow oxidative, fast oxidative, fast glycolytic

slow oxidative

slow, barely fatigue, little tension, dark red

fast oxidative

fast, fatigue over time, decent tension, red

fast glycolytic

fast, quickly fatigue, high tension, pale

smooth muscle single unit

cells connected by gap junctions, contract together

smooth muscle multi unit

cells each connected to axon and varicosities

smooth muscle contraction type A

generally at rest, contracts, returns to rest

smooth muscle contraction type B

cycle of contraction and relaxation

smooth muscle contraction type C

generally contracted, relaxes, returns to contraction

smooth muscle contraction type D

always slightly contracted, fluctuates

smooth muscle contraction calcium step 1

calcium enters from interstitial fluid

smooth muscle contraction calcium step 2

calcium binds to calmodulin and activates myosin light chain kinase (MLCK)

smooth muscle contraction calcium step 3

MLCK phosphorylates myosin heads to increase myosin ATPase activity

smooth muscle contraction calcium step 4

calcium pumped back into sarcoplasmic reticulum

smooth muscle contraction calcium step 5

calcium and calmodulin unbind, stopping MLCK

tension develops slowest in ___ muscle

smooth

vascular system purpose

deliver oxygen and nutrients and remove waste

average blood volume

5.5 liters

blood composition

45% hematocrit, 1% leukocytes, 55% plasma

red blood cell count

5 million per micro liter

white blood cell count

thousands

red blood cells have no

nucleus or ribosomes

erythropoeitin

hormone from kidney that stimulates red blood cell production

leukocytes are ____ than erythrocytes but there are ____

larger, fewer

leukocyte

white blood cell

erythrocytes

red blood cell

right heart pumps to

pulmonary system (lungs)

left heart pumps to

rest of body (tissues)

flow is ___ at every level

the same

velocity of blood is determined by the

total cross sectional area

capillaries have the ___ velocity

lowest

flow equation

change in pressure / resistance

blood flows along pressure gradient

high to low pressure

pericardium

sac of fluid that surrounds heart

valve energy source

none, pressure driven

mitral valve function

prevent blood from flowing into atrium from ventricle

semilunar valve function

prevent blood from flowing into ventricle from aorta or pulmonary artery

intercalated disks contain

desmosomes (physical connection) and gap junctions (electrical connection)

types of cardiac cells

contractile (myosin), autorhythmic (pacemaker)

calcium induced calcium release

calcium from voltage gated calcium channel releases calcium from sarcoplasmic reticulum

cardiac muscle contraction calcium step 1

action potential enters t-tubule and opens voltage gated calcium channel

cardiac muscle contraction calcium step 2

calcium induced calcium release through ryanodine receptors

cardiac muscle contraction calcium step 3

calcium sparks sum to calcium signal

cardiac muscle contraction calcium step 4

calcium binds to troponin and causes contraction

cardiac muscle contraction calcium step 5

calcium pumped back into sarcoplasmic reticulum and unbinds from troponin

cardiac muscle contraction calcium step 6

calcium replaced by sodium through sodium potassium ATPase

why does the myocyte action potential have a plateau?

to prevent the heart from continuously contracting

heart conducting system step 1

SA node depolarizes