circulation Flashcards
general characteristics of circulatory system
one or more pumps or structures that apply force to drive fluid flow through system of tubes, and a fluid that circulates through the system
Open circultory system
organisms with open circulatory systems have generally blood pressures
closed circulatory system
organisms with closed circulatory systems have higher blood pressure
why do closed circulatory system have higher blood pressures
allows for rapid adjustment of O2 and nutrient delivery to specific tissues, ultra filtration of the blood
Structure of Blood vessels: Large vein, elastic artery, vein, and muscular artery
Tunica externa, tunica media, tunica intima
Tunica Externa
external part of the blood vessel, is is made of collagen
Tunica Media
middle layer of blood vessel, made of smooth muscle and elastin
Tunica Intima
inner layer, made of endothelial cells and laminin
Venule
made of tunica externa and tunica intima, does not have tunica media
Arteriole
tunica media and endothelium
Capilaries
Made of only tunica intima and vary in structure
Continuous capillary
in the brain muscle and skin (have tight junction, endothelial cell, and intercellular cleft)
Fenestrated Capillary
Kidney, endocrine organs, intestines (tight junctions, endothelial cell, intercellular cleft, fenestrations (pores)
Sinusoidal capillaries
liver, bone marrow ( tight junction, endothelial cell, intracellular cleft
Bulk flow
bulk flow of blood is controlled by tubes, pumps, and values increased pressure of valves increases flow down the one way valve
equation for Bulk flow
Q (flow)= delta P (pressure gradient x R (resistance)
law of bulk flow
fluids flow down pressure gradients, resistance due to frication opposes this movement. The law of bulk flow quantifies the relationship between flow, pressure and resistance
relationship between resistance and radius of tube
resistance is inversely related to radius (R=8nL/pir^4)
what are the assumptions of Poiseuilles equation and why are they wrong
the equation assumes unbranched rigid tubes that are uniform simple tube with steady flow. Blood vessels are not simple continuous tubes
Flow in a closed circuit
in a closed circuit flow will be uniform at all points of the circuit
Velocity of fluid
velocity of fluid flow is inversely proportional to the area of the vessel Blood velocity= Q flow/ A (summed cross sectional area of flow)
blood velocity in an open circuit
velocity will not be uniform at all point
where is blood velocity the lowest and cross sectional area the highest
at the capillary beds
where do blood cells flow through
flow through the capilaries and the venules
Structure of Vertebrate heart walls
endocardium is outside, then myocardium, pericardium
Where is the coronary artery
in the myocardium
Pericardium
inner most layer of heart wall, its first layer is the epicardium (visceral pericardium) then pericardial fluid which in the pericardial cavity, then the parietal pericarium
Diastole
relaxation phase of cycle, negative blood pressure, blood flowing in
Systole
contraction, positive pressure, blood flows out
are valves active or passive
valves are passive
AV values: Atrial → Ventricular
Right is tricuspid, left is bicuspid/mitral, the AV valves are weak enough to open with pressure but strong enough not to prolapse which is prevented by the chordae tendinae and papillary muscles
Semilunar valves: ventricular→ out
pulmonary value, aortic valve. Weak enough to open from ventricular contraction which allows blood to flow out of the heart but they are strong enough to withstand return pressure
Atrial diastole/ Ventricular diastole:
pulmonary value is closed, tricuspid and mitral valves are open, aortic value is closed, atrial systole, ventricular diastole
Atrial diastole/ Ventricular systole:
pulmonary value open, tricuspid and mitral valves closed, aortic valve open, atrial diastole, ventricular systole
what does the SA node Ionic Conductase do
it creates a self sustaining pacemaker
what is the funny current
cased by non selective cation channels that open at hyperpolarized voltages and close upon depolarization
What is the most important ion for the Funny current
Na+
what does the depolarization of the pacemaker do
it spreads to the neighboring cardiomyocytes causing action potentials and contraction
timing of the depolarization of the SA node pacemaker
- SA node depolarizes, and the depolarization spreads rapidly via the internodal pathway
- The av Node delays the signal, the depolarization spreads rapidly though the atria via gap junctions and causes the atria to contract
- depolarization spreads rapidly though the bundle of His and purkinji fibers
- the depolarization spreads upward through the ventricles causes them to contract
EKGs detect what
integrated electrical activity of the heart
P wave
depolarization of aorta, the first small wave
QRS
depolarization of the ventricles and repolarization of the atria. The first part of the spike is Q, the peak is R and the come down is S which is the repolarization of the ventricels
Electrical and mechanical events of the heart are coupled
start cycle with ventricular diastole, then around the P wave you move to atrial systole, the in the QRS complex you get isovolumetric contraction, after the QRS complex you have ventricular systole, at T wave you have isovolumetric relaxation, then you have ventricular diastole before you start the cycle over again
relationship of cardiac output to heart rate and stroke volume
Cardiac output is the product of heart rate and stroke volume CO=HRxSV
how do parasympathetic and sympathetic branches of autonomic nervous system control HR
the reciprocally control heart rate by controlling the pacemaker potential and the SA node
how does parasympathetic nervous system slow SA node pacemaker
Via muscarinic ACh receptors Cardiovascular control center (medulla) → Parasympathetic neurons → Ach→ muscarinic receptors of autorhythmic cells→ leads to increase K+ efflux and decrease in Ca influx → hyperpolarizes the cells→ increases the time for depolarization → decreases heart rate
how does sympathetic nervous system accelerate the SA node
via beta adrenergic receptors, reduced repolarization, faster depolarization
how does sympathetic nervous system modulate the force of heart contractions
increasing force of contractions increases stroke volume which increases cardiac output
what is driving force of blood flow through the circulatory system
Pressure caused by ventricular ejection
Blood pressure in different regions of circulatory system
highest BP is in the left ventricles then arteries, aterioles, capillaries, venules and the lowest BP is in teh veins
Systolic pressure
highest arterial blood pressure, associated with ventricular contraction
Diastolic pressure
lowest arterial blood pressure, associated with ventricular relaxation
relationship btw MAP, CO, and resistance
Mean arterial pressure is the average blood pressure in the arteries across the cardiac cycle
Q=ΔP/R
CO= Mean arterial pressure/ Total peripheral resistance (TPR)
MAP= CO x TPR
how is mean arterial pressure regulated
barroreceptors monitor blood pressure and signal to cardiovascular control center of medulla
how is local blood flow controlled
by altering the diameter of the arterioles leading to the capillary beds
Intrensic mechanisms of blood flow control
metabolic or myogenic controls, distribute blood flow to each individual organ and tissue as needed
Extrensic mechanisms of control of blood flow
neutral or hormonal controls, maintain MAP, redistribute blood during exercise and thermoregulation
