Exam 3 CVS 5-8 Flashcards
The function of the ventricles is defined by 3 factors:
- stroke volume
- ejection fraction
- cardiac output
The volume of blood ejected on one ventricular contraction
Stroke volume
stroke volume is the difference between:
the volume of blood in the ventricles before ejection and the volume remaining after ejection
the fraction of the end diastolic volume that is ejected on one stroke volume
ejection fraction
the inc. or dec. in ejection fraction reflects and inc. or dec. in ______
contractility
the total volume of blood ejected per unit time
CO
4 factors that affect CO:
- body metabolism
- exercise
- age
- body size
Cardiac output can be increased if ____ or ____ are increased
SV; HR
three things that affect stroke volume:
- Preload
- contractility
- afterload
If end-diastolic volume increases then SV will_____
increase
If end systolic volume is decreased then SV will____
increase
The workload imposed on the heart before contraction begins
Preload
what are the 2 factors that determine preload?
- diastolic filling
2. venus return
what is another term for preload?
end diastolic volume
What does the frank-starlin mechanism state?
the volume of the blood ejected by the ventricles depends on the volume present in the ventricle at the end of diastole
The pumping ability of the ventricle
contractility/ inotropism
an increase in contractility leads to a/an ______ in stroke volume
increase
an increase in contractility leads to a/an ______ in systolic volume
Decrease
what are 2 extrinsic factors that have a positive ionotropic effect? (inc. contractility)
- sympathetic stimulation
2. cathecolamines
how doe epi and norepi stimulate an inc. in contratility?
stimulation of Beta 1 receptors to inc. Ca flow
the resistance that the ventricles must overcome to empty its content?
Afterload
what is the afterload for the L ventricle?
Aortic pressure
An inc. in afterload will cause a/an ______ in ionotropy (contractility)
How?
increase, catecolamines
sympathetic stimulation increases or decreased HR?
increases
When HR increases, contractility _______
increases
Inc. in preload causes stroke volume to _____
Inc.
Inc in contractility causes SV to ______
Inc
Dec. in afterload causes SV to _____
Inc
what are the 3 major divisions of the circulatory system?
- distribution system
- perfusion/exchange system
- collecting system
What makes up the distribution system?
Ventricles, arteries, arterioles
What makes up the perfusion/exchange system?
capillaries
What makes up the collecting system?
Venules, veins, atria
transports blood under high pressure to tissues
Arteries
the last, smallest branches of the arterial system?
arterioles
Site of the highest resistance to blood flow
Arterioles
What 2 types of receptors can be found in the arterioles?
Alfa-1 adrenergic; Beta-2 adrenergic
What do the ALFA-1 receptors in the arterioles do when stimulated
cause contraction of the smooth muscle
What do the beta-2 receptors in the arterioles do when stimulated?
relaxation of smooth muscle
Exchange fluid, nutrients, electrolytes, hormones, and other stuff between the blood and interstitial fluid.
Capillaries
collect blood from the capillaries and gradually coalesce into progressively larger veins
venules
function as conduits to transport the blood from the venules back to the heart
veins
serves as a major reservoir for extra blood
veins
what prevents blood from flowing in the reveres direction in veins?
valves
how long does blood stay in capillaries?
1-3 sec.
As cross section increases, blood flow____
Dec.
blood flow through a blood vessel depends on 2 factors:
- pressure diff. (betw. 2 ends of vessel)
2. resistance
what determines the direction of BF?
direction of pressure gradient
What does Poiseuille Equation tell us?
the relationship between resistance, blood vessel diameter, and blood viscosity
The volume of blood the vessel can hold at a given pressure
compliance/capacitance
Is the compliance of veins high or low?
High
What is included in central circulation?
R heart + Pulmonary circuit + L heart
The amplitued of pressure pulsations in an artery
Pulse pressure
is pulmonary circulation a Low/High pressure circulation
Low
Is systemic circulation a Low/High pressure circulation
High
The pressure at the top of each pressure pulsation
systolic pressure
the highest arterial pressure measured during a cardiac cycle
systolic pressure
The pressure in the arteries after blood has been ejected from the L ventricle
Systolic pressure
closing of the aortic valve- a brief period of retrograde flow
incisura
The pressure at the lowest point of each pulse
Diastolic pressure
the lowest arterial pressure
Diastolic pressure
the pressure in the arteries during ventricular relaxation
diastolic pressure
The diff. between systolic pressure and diastolic pressure
pulse pressure
The average pressure in a complete cardiac cycle
mean arterial pressure (MAP)
Why does MAP= diastolic pressure + 1/3 Pulse pressure?
B/c a greater fraction of each cardiac cycle is spent in diastole
Pressure that continuously drives blood into the tissues over the course of the cardiac cycle?
MAP
what monitors MAP?
blood pressure reflexes
The resistance of the systemic circ.
Total peripheral resistance (TPR)
T/F arterial pressure in systemic circ. is lower than venous pressure
F. Venous pressure is lower than arterial pressure
What is another name for central venous pressure (CVP)
R atrial pressure
the central venous pressure is regulated by:
- ability of heart to pump blood out of the R atrium and ventricle to the lungs
- tendency for blood to flow from the peripheral veins to the R atrium
3 Factors that inc. CVP
- inc. blood volume
- inc. in large vessel tone
- dilation of the arterioles
ANYTHING THAT CAN INC. VENOUS RETURN!
What are the 2 factors that regulate MAP?
- Baroreceptor reflex
2. RAAS
A fast, neurally mediated reflex that attempts to keep arterial pressure constant via changes in the output of the sympathetic and parasympathetic systems
Baroreceptor reflex
A hormonal system that regulates MAP primarily by regulating blood volume
RAAS
Where are baroreceptors located?
in the walls of the carotid sinus and aortic arch
Baroreceptors are sensitive to ______
pressure or stretch
the baroreceptor reflex is a reflex arc composed by what 4 things:
- Receptors for BP
- Afferent neurons
- Brain stem centers
- efferent neurons
T/F RAAS is quicker than the Baroreceptor reflex in controlling MAP
F. slower
What activates RAAS?
Dec. in MAP
What are the 5 steps of RAAS?
- Dec in MAP stimulates kidney to produce renin
- Renin causes angiotensinogen to convert to angiotensin I
- Angiotensin I is converted to angiotensin II in lungs
- Angiotensin II stimulates Adrenal cortex to produce aldosterone
- Aldosterone inc. blood volume
How does aldosterone, produced during RAAS, increase blood volume
increases sodium, chloride, and water absorption
excretion of K+
AngiotensinII acts on the hypothalamus to do what?
Inc. thirst and produce ADH
Name 4 other mechanisms that also aid in regulating MAP?
- chemoreceptors for O2
- chemoreceptors for CO2
- ADH
- Atrial natriuretic peptide
where are peripheral receptors for O2 located?
carotid and aortic bodies
What is the primary function of the chemoreceptors for O2 located in the carotid and aortic bodies?
control of breathing
Cardiopulmonary low pressure baroreceptors located in the veins, atria and pulmonary arteries
cardopulmonary volume receptors
what do cardopulmonary volume receptors do?
sense changes in volume
The response to an inc. in blood volume includes what 4 actions?
- inc. secretion of ANP
- dec. secretion of ADH
- Renal vasodilation
- inc HR
