NPB101 MT1: homeostasis/muscles/cardio syst

mitochondria

creates ATP (energy) in the body

nucleus

cell control center

cytoplasm

consistent pH, intracellular transport

ribosome

protein synthesis

lysosome

breaks down certain proteins

endoplasmic reticulum

synthesize exterior cell + proteins/lipids

golgi complex

enclosed sacs that modify from ER, secrete vesicles, sort and direct

4 primary types of tissues

muscle, nervous, connective, epithelial

organ

structure composed of several types of tissues

homeostasis

maintenance of a dynamic steady state in the internal environment

what 3 fluids are exchanged in homeostasis?

intracellular fluid, intersitial fluid, blood (plasma)

homeostatic control system

sensors (detect change), control center (integrates info), effectors (makes adjustments)

negative feedback

counteracts deviations from the set point in the OPPOSITE direction of intial change

positive feedback

amplifies initial change AWAY form the set point

what are the two forms of direct intercellular communication?

gap junctions and transient direct linkup of cell’s surface markers

what are the two forms of indirect intercellular communication via chemical messengers?

paracrine secretion and NT secretion

function of muscles

turn chemical potential energy into mechanincal energy (smooth, cardiac, and skeletal)

smooth muscles

no striations, involuntary and found in stomach, airways, and blood vessels

cardiac muscles

striated, involuntary, one nucleus per cell, intercalated disks

skeletal muscles

long, multinucleated, striated, voluntary

sarcomere

smallest unit of muscle cells containing all of the elements for contraction in striated muscles. composed of myosin and actin

thick filament

myosin composed of long interwoven protein with globular head

thin filament

actin, troponin, and tropomyosin in a double helical structure

what happens to parts of sarcomere during contraction?

the sarcomere shortens, H zone shortens, I band shortens, all other parts stay same length

cross bridge cycle/activity

ACh produced in MN, Na+ ch open, AP flows thru sarcolemma and t-tubules, Ca2+ release, Ca2+ binds to troponin C, I, and T, then moves tropomyosin out of blocking position for binding, crossbridge binds to actin, Pi released then ADP released, powerstroke and filaments slide, sarcomere gets smaller and new ATP binds to head, ATP is hydrolyzed and cycle resets

excitation contration coupling

muscular contraction when the thick and thin filaments in sarcomere slide past one another by a power stroke

motor unit

motor neuron and all the fibers it innervates (1 MN has many fibers, each fiber has 1 MN)

muscle tension

tension that depends on the number of motor untis recruited based on frequency, length, extent, and thickness

twitch summation

increase in tension by repetitive stimulation of a muscle fiber (muscle can never fully relax)

tetanus

smooth, sustained contraction of maximal strength so rapid cannot relax between stimuli

muscle fatigue

inability of muscle to maintain tension

smooth muscle contraction

muscle contraction by sliding filament mechanism (no sarcomere): excited, Ca2+ messenger activated calmodulin, myosin light chain kinase, cross bridge cycle

multi-unit smooth muscle

activated by neuronal input for an independent response

single-unit smooth muscle

capable of pacemaker activity by gap junctions

circulatory system

heart, blood vessels, and blood. function: to supply O2 and nutrients, remove waste, regulate temp, distribute hormones, and immunovigalance

right atrium

receives O2 poor blood from systemic venous circulation

right ventricle

receives O2 poor blood from right atrium and pumps blood through pulmonary (semilunar) valve to pulmonary artery

left atrium

receives O2 rich blood from pulmonary circulation from left and right pulmonary veins

left ventricle

receives O2 rich blood from left atrium and pumps this blood through aortic (semilunar) valve into aorta

what does #1 correspond to on this image?

vena cava

what does #2 correspond to on this image?

right atrium

what does #3 correspond to on this image?

tricuspid (right AV) valve

what does #4 correspond to on this image?

right ventricle

what does #5 correspond to on this image?

left ventricle

what does #6 correspond to on this image?

pulmonary/semilunar valve

what does #7 correspond to on this image?

mitral/left AV valve

what does #8 correspond to on this image?

aortic/semilunar valve

what does #9 correspond to on this image?

left atrium

what does #10 correspond to on this image?

aorta

what does #11 correspond to on this image?

pulmonary artery

what does #12 correspond to on this image?

pulmonary veins

why are heart valves important and which is strongest/weakest valve?

important for one-way blood flow. semilunar is the strongest, tricuspid is the weakest

what are the 3 layers of the heart wall?

endocardium, myocardium, epicardium

contractile cells

99% of cardiac muscle cells, do mechanical work of pumping

autorhythmic cells

1% of cardiac cells, conduct APs for contraction, pacemaker

nodes

pacemaker cells grouped together for control rate and coordination

SA node

pacemaker node in right atrium. acts as a sensor, fastest and most dominant node (70 APs/min)

AV node

pacemaker node at base of right atrium (50 APs/min)

Bundle of His

starts at AV node and divides into left and right ventricles (40-60 APs/min)

Purkinje Fibers

fibers of pacemaker cells in bundle of his to ventricular myocardium (30 APs/min)

interatrial pathway

conduct pacemaker activity from right atrium to left atrium

internodal pathway

conduct pacemaker activity from SA node to AV node

electric flow in heart

SA node —> AV node —> Bundle of His —> L/R bundle branches —> Purkinje Fibers

vein

blood vessel that carries blood TOWARDS the heart

artery

blood vessel that carries blood AWAY from the heart

flow of deoxygenated blood

blood from the body —> vena cava —> right atrium —> tricuspid valve —> right ventricle —> pulmonary valve —> pulmonary artery —> lungs

flow of oxygenated blood

oxygenated blood from the lungs —> pulmonary veins —> left atrium —> mitral valve —> left ventricle —> aortic valve —> aorta —> body

systole

contraction and emptying

diastole

relaxation and filling

isometric ventricular contraction

valves are CLOSED and pressure increases

isometric ventricular relaxation

valves closed and pressure decreases

stroke volume

amount of blood pumped out of the chamber with each contraction

action potential in contractile muscle cells

rapid rising phase due to Na+ entry, repolarization due to K+ ch open and Na+ inactivated, plateau due to slow Ca2+ entry, falling phase with K+ efflux and K+ ordinary ch opening, resting potential maintained by leaky K+ ch

excitation contraction coupling in cardiac cells

Ca2+ entry —> dihydropine receptors —> power stroke —> cross bridge with graded response to regulate heart beat

when does the heart make a sound

when a valve CLOSES

first heart sound

“lub”, closure of AV valve

second heart sound

“dub”, closure of semilunar valve

what is an electrocardiogram (ECG)?

electrical currents generated by APs of heart muscle

p wave of ECG

depolarization of atria, pacemakers go from SA node to AV node

PR segment of ECG

AV nodal delay

QRS segment of ECG

depolarization of the ventricles

ST segment of ECG

ventricles contracting and emptying

t wave of ECG

repolarization/relaxation of ventricles

regulation of cardiac output (C.O.)

volume of blood pumped in each ventricle per minute determine by heart rate and stroke volume: C.O. = H.R. x S.V.

heart murmur

abnormal heart sounds due to malfunctioning valves

stenotic valve

valve does not OPEN completely: whistling sound

insufficient valve

valve does not CLOSE properly: swishing sound