Physiology Section 2

Describe cardiac muscle: striated? voluntary? how many nucleus? peristaltic?

striated, involuntary, single nucleus, not peristaltic

Describe smooth muscle: striated? voluntary? how many nucleus? peristaltic?

not striated, involuntary, single nuclease peristaltic

What does it mean if something is peristaltic?

it moves in a wave like motion

Whole muscle

muscles bundled together and surrounded in tissue

Muscle fasicles

bundles of muscle fibers surrounded by muscle fascia

Muscle fiber

single muscle cell

Myofibrils

intracellular portion of the muscle fiber; composed of thick and thin filaments

What is thick filament in the muscle made of? Thin filament?

myosin, actin

A Band

length of the myosin

H zone

space between actin filaments

Z line

thin filaments are anchored to this

I band

thin filaments only

Sarcomere

contractile unit of a muscle fiber containing actin and myosin

Titan elastin filaments

stretch muscle out and keep things central, like spring

M line

center of sarcomere

the head of myosin can __

pivot/ratchet

Myosine ATPase

ATPase used ino skeletal muscle to help contract

What happens when muslce fibers contract

H zone gets smaller but myosin is same size

Steps of muscle fiber contraction

myosin heads gind to actin and form cross bridge, ATPase binds to crossbridge, mysoin head ratches w/ ATP and uses energy to form ADP, thick filaments pull the z line to the M line, z lines moves closer together and h zone is smaller

What is the structure of actin? myosin?

helix; strand with head

Tropomyosin

protein that blocks the myosin binding sites; when present, muscle can't contract

Troponin

binding protein that controls position of tropomyosin on the actin helix

Ca 2+ ions

bind to the troponin, forcing it to slide off the myosin binding site on helix

The control of musclular contraction depends on the...

somatic motor neuron (SMN)

1 somatic motor neuron can control ___ muscle cells. amount depends on if needed for power or precision

3-1000

Sarcolema

membrane of muscle cell

Sarcoplasmic reticulum

Organelle of the muscle fiber that stores calcium to later go to the muscle

Calsequestrin

Protein in cisternae of cytplasmic reticulum that buffers Ca2+ ions and allows them to hold 10x more Ca2+; allows the muscle to relax

What happens once action potential has passed the T-Tubules

Ca2+ voltage gates close, Ca2+/ATPase pumps Ca2+ back into cisternae (via active transport), and tropomyosin covers actin so muscle relaxes

How is Ca2+pumped back into the cisternae?

Ca2+/ATPase

Why does rigor mortis happen?

Ca2+ moves into body and never relaxes, no energy to bring back into cisternae

secondary flaccidity

Happens after rigor mortis and is when the muscle starts to decay

Stronger whole muscle response requires...

increased recruitment of muscle cells

What is a motor unit?

somatic motor neuron + associated msucle cells

Smaller motor neurons have (fewer/many) muscle cells and provide __ movement

fewer, precise

Large motor neurons have (fewer/many) muscle cells and provide __ movement

many, power

Asynchronous recruitment

alternation of active motor units to prevent fatigue

A normal muscle cell stores enough ATP for ___ seconds of work

4-6 secs

What are the 3 ways to form ATP for muscle cells?

creatine phosphate, oxydative phsophorylation, and glycolysis

Creatine Phosphate

high energy phosphate carrier, very fast at creating ATP

How does Creatine Phosphate (CP) form energy

CP and ADP use creatin kinase to form creatin and ATP

Muscle stores enough energy from Creatine Phsophate for __ seconds of work

15-20

oxidative phosphorylation

way to make ATP for muscle cell; uses aerobic respiration and is realtively slow but has a high ATP yield; requries constant supply of O2 provided by myoglobin

What is the ATP yield for oxidative phosphorylation? ATP yield for Glycolysis?

38 ATP per 1 glucose; 2 ATP per 1 glucose

Myoglobin

form of hemoglobin in the muscle cell; provides a store of oxygen for aerobic respiration

Glycolysis

makes ATP for muscle cells using anaerobic respiration; very fast but ineffective and produces lactic acid as waste product

types of muscle fiber

slow-oxidative fibers (red), fast glycolitic fibers (white), fast-oxidative fibers (pink)

Slow Oxidative fibers--red

small muscle fibers taht contract slowly; use aerobic respiration; has lots of mitochondria, myoglobin, and capillaries

What movement is slow oxidative fibers good for?

low intensity and endurance

Fast Glycolitic fibers--white

large muscle fibers that are large and many myofibrils; contract quickly and w/ great force; have high ATPase activity; use glycolysis--few mitochondria, myoglobin, and capillaries, lots of glycogen and glycolitic enzymes

What kind of movement is fast glycolitic fibers good for?

high intensity and short endurance

Fast Oxidative fibers--pink

Medium sized fibers that contract quickly with good force

How do fast oxidative fibers form ATP?

mostly oxidative phosphorylation but can fall back to glycolysis

What kind of movement is fast oxidative fibers good for?

intermediate activity and circuit use

Fatigue

Muscle no longer responds with the same force/tension of contraction in response to action potential

What are the 3 types of fatigue?

muscle fatigue, neuromuscular fatigue, or psychological fatigue

What are the 3 reasons for Muscle fatigue?

increased [P] causes a decreased amount of Ca2+ released (less Ca2+, bridges not forming);

depleted Ca2+ reserves in sarcoplasmic reticulum;

depleted glycogen reserves

Why does depleated Ca2+ reserves in the sarcoplasmic reticulum cause fatigue?

longer you work, the less Ca2+ is available; also lose Ca2+ to the interstitium

Why does depleated glycogen in reserves cause fatigue?

no energy to make more ATP

What does the myosin bind to when contracting muscles?

actin myosin binding sites

Acetylcholine Esterase

enzyme that breaks down acetylcholine into acetyl and choline using enzymatic degradation

Neuromuscular fatigue

Acetylcholine synthesis is too slow to keep up with high intensity demand (enzymatic degredation breaks down and can't build up fast enough)

Psychological fatigue

CNS does not activate motor neuron units; could be because of lack of NT or more often CNS response to pain and exhaustion

cellular gas exchange in the pulmonary circuit depends on...

source/sink

bulk transport

The process by which large particles and macromolecules are transported through plasma membranes. Inc. exocytosis and endocytosis

in pulmonary circuit, the muscle cell is a source for __

CO2

in the pulmonary circuit, the alveoli is a source for __

O2

The source is always the molecule with (high/low) concentration because...

high, easy to move to lower concentration

CO2 and O2 are (hydrophilic/hydrophobic) which means they can move across the membrane (easily/not easily)

hydrophobic, easily

Cellular gas exchange requires...

a diffusion gradient

Gases are measured by...

partial pressure

What does Dalton's law of partial pressure say?

total pressure=partial pressure of individual gases

Partial pressure of a gas is realtive to it's __

abundance

What is the normal sea-level atmosphereic pressure?

760mm Hg

What are the most abundant molecules in the atmosphere?

N2 then O2 then CO2

what is the bulk flow of O2? bulk flow of CO2? (going from atmosphere, alveoli, oxygenated blood, tissue cells, deoxygenated blood)

bulk flow of O2 goes down; bulk flow of CO2 goes up

Which of the following has the highest solubility? Which has the lowest? CO2, He, N2, and O2

CO2 (0.57) is highest (O2 (0.024), N2 (0.012)) and He (0.0048) is lowest

Internal respiration involves the transport of...

O2 and CO2

What molecule helps transport CO2?

HbCO2--carbaminohemoglobin

How do you make carbaminohemoglobin? is it reversible?

Hb + CO2--> HbCO2 it is reversible

What does Hb stand for?

hemoglobin

How do you form carboxyhemoglobin? Is it reversible?

Hb + CO2--> HbCO; non reversible and deadly

How much of the plasma concentration is HCO3-? How much is HbCO2? and CO2?

70%, 23%, and 7%

Most CO2 in plasma is carried as __ ions using...

bicarbonate; bulk transport

HCO3-

helps with rapid movement of CO2 and is the main pH buffer for plasma

How is carbonic acid formed (H2CO3)?

Co2 and H2O combine with carbonic anhydrase

What does carbonic acid do in the interstitium and plasma?

H2CO3<-->H+ + HCO3- ; increased HCO3- in the plasma causes shift of Cl- to increase Cl- in RBC

What does carbonic acid (H2CO3) do in the alveoli?

H2CO3--> H2O + CO2 ; decreased carbonic acid causes decreased HCO3- in plasma and lowers Cl- in the RBC (CO2 goes into environment)

What chemical equation shows the whole body pH buffer using bicarbonate?

H2CO3<-->H+ + HCO3-

Hypercapnia

too much or too high CO2 in the lungs; causes increased HCO3- in plasma and yawns

Hypocapnia

too low or little CO2 in the lungs; causes decreased HCO3- in the plasma and hiccups

What percent of transport of O2 is done by HbO2? what percent is done by plasma?

98.5, 1.5

What pO2 and HbO2 saturation is livable? which is deadly?

(livable) 60mmHg and 90% saturation; (deadly) 50 mmHg and 85% saturation

what chemically happens in the loading of O2?

Hb + O2 --> HbO2

What chemically happens in the unloading of O2?

HbO2 --> Hb and O2

O2 loading and unloading depends on the...

affinity of Hb for O2

What 3 thigns determine the Hb affinity of O2?

pO2, pH, and pCO2

As pO2 decreases, Hb affinity (decreases/increases)

decreases

As pH decreases, Hb affinity (decreases/increases). also called the...

decreases; bohr affect

As pCO2 increases Hb affinity (decreases/increases)

decreases