physiology lab Flashcards
What e the events that occur during each phase of the action potential in the SA node
- Na+ coming in, also ca++ in through leaky channels
- Fast depolarization Ca++ influx through voltage gated channels
- Fast repolarization K+ influx via voltage gated channel
What are the events that occur during each paste of plateau action potential
- Slow depolarization - Na+ in via leaky channels
- Rapid depolarization Na + in via voltage gated channels
- Plateau Phase- Ca++ influx , K+ bleak channels (n ligand)
- Rapid depolarization- K+ efflux via voltage gated channels
- Slow depolarization – Na+ influx leaky
Compare and contrast the major physiological characteristics of the Sa node and av nodes and the specialized conductive fibers
SA node – resting potential is closer to threshold
Resting potential= -60 to -50mV
HR= 60- 100
AV node — slower in conduction -fewer gap junctions – smaller in diameter size(greater resistance)
Resting potential = -85 to -75mV
HR= 40-60
Ventricle - resting potential= -105 to -95 mV
HR= 20-40
What are the effects of hyperkalemia, Hypercalcemia and hypocalcemia on cardiovascular function? What are the molecular events that cause these problems
Hypercalcemia— excess ca++ in blood= stronger contractions = it will block opening of voltage gated Na+ channels ( blocks neurons)
Hypocalcemia- Less ca in blood = weaker contractions=causes spontaneous opening of Na+ channels (muscle tetany)
Hyperkalemia- increase K= outside the cell= more K+ inside the cell= making the cell less negative= weaker contraction
Hyperkalemia
More K+ outside the cell= less force inside the cell= less negative
Less Ca+ entry inside cell
Weaker contractions= slow contractions = irregular rhythm =AV block
Less negative resting potential= weaker contraction
The roles of the sympathetic and parasympathetic nervous system in regulating the heart. Describe in detail how Ach and Norep alter cardiac functions
Parasympathetic effects only rate
- Ach binds to ligand gated channels - increases K+ permeability = decreases heart rate
Sympathetic - effects strength and rate
- norep= hyperpolarizes membrane potential closer to threshold - increases Na+ permeability - increaseHR - more Ca++ channels available -increases strength
Define Right (RAD) and left axis deviations (LAD) detected with ECG’s . What are the normal body variations that may cause their appearances and what pathological conditions might be responsible?
RAD- picking up more electrical activity on right ( 90- 180)
- right vent. hypertrophy
- increase resistance to blood flow in pulmonary circuit
- People who have adapted to living at high altitude
LAD- 0 to -90 (-270)
- occurs in obesity, pregnancy
- can occur lying down
- enlarged left ventricle
- loss of right ventricle muscle cells depolarizing
Extreme RAD
180-270
- most serious not good for physical activity
- muscle left decreased at same time when right muscle increases
- result from congested heart failure
- leads to pulmonary edema
Ohm’s law How pressure differences and resistance affect fluid flow
the pressure differential between the pressure at the origin of the vessel and the pressure at the other end of the vessel . the difference creates a resistance as a result of friction between the flowing blood and the intravascular endothelium along the inside of vessel
Poissseuille’s law how radius, resistance, length, viscosity turbulence and hematocrit affect blood flow
Turbulence: when rate of blood flow becomes too great, passes by an obstruction in a vessel
Radius:
Factors that affect cardiac output and total peripheral resistance
Cardiac output= arterial pressure / TPR
when total peripheral resistance decreases, the cardiac output increases
when total peripheral resistance increases the cardiac output decreases
Define Mean arterial pressure (MAP)
average pressure pushing blood through systemic circulatory system
the equations for estimating MAP at rest and during activity
At rest: MAP= 1/3(SP-DP)+DP
Activity: MAP= SP+DP/2
Blood pressure = Cardiac output X ….
Blood pressure= ___ X__ X___
Blood pressure=__X ______X ___
TPR
HR X SV X TPR
HR X (EDV- ESV) X TPR
Resistance = 8nL/ ?
r ^4
Blood Flow= P1-P2/ ?
R
Cardiac Output
SV X HR
Stroke Volume=
EDV-ESV
Intrinsic control
Sa node/ AV node ectopic focus increase stretch of right atrium increase leakiness SA node increase HR increase venous return increase peripheral tissues increase vasodilators
Extrinsic Control
Bainbridge reflex
increase pressure in R atrium
increase sympathetic
baroreceptors
what is the Baroreceptor reflex: - variable measured - sensory receptors - intergrating center - efferent pathway response of the effectors
- initiated by stretch receptors - increased BP
- Carotid sinus and aortic arch
- signals to CNS
- feedback ANS
- reduce arterial pressure and decrease HR
- Blood volume decreased
Bainbridge reflex
Stretch receptor of right atria
transmits back through vagus nerves and sympathetic to increase HR
Bood volume increased
venous return is increased- increase pressure on right atrium - decreased atrial pressure - brings more blood in from vena cava
Action of ADH
-vasoconstriction
- increase HR
-
- increase BP
- reabsorb water
decrease osmotic pressure
Aldosterone Action
- increase Na+
- excrete K+
- increase BP
Angiotensin II
- vasoconstriction
- increase BP
Atrial Natriuretic Hormone
- decrease BP
- Vasodilation
- decrease Na+
