Cardiovascular System Flashcards
Blood Flow: Role of pressure
The CV system exists to perfuse — with sufficient — to meet their — needs.
The needs differ and change.
Blood must be distributed —
Transport + distribution of fluid requires —
Basic Principle:
The — provides energy for distributing —
—/— provide resistance to —
The interaction of the heart and vessels causes —/–
tissues blood metabolic accordingly pressure
heart blood blood vessels flow blood pressure
Blood flow through vessels depends on:
Pressure gradient:
the pressure — along the tube as — is lost through — with the walls.
Flow depends on —
The vessel — is very important when analysing flow.
drops energy friction (Delta)P radius
Pressure drop throughout circulation is greatest in vessels which offer the highest —.
These are the —
resistance
arterioles
Blood Flow velocity- Influence of vessel area:
The same — of blood is moving at any point in the —.
The velocity depends on the —/— of those vessels.
The aorta is wide and there is only one so velocity is —.
The capillaries are tiny but there are millions so the velocity through them is —
volume circulation cross-sectional area High low
Blood Vessels and the CV System:
Arteries distribute blood from the —
They have — walls as they are under — pressure
They are elastic- stores energy to maintain —/— during –
Variable resistance controls local —/—
The vessels which exchange with cells are called —
The veins are collective and take blood to the —
They are — walled as they are under — pressure.
Valves ensure — flow
heart thick high blood pressure diastole blood flow capillaries heart thin low uni-directional
Blood Vessel Structure (In to Out):
- ) —
- ) — layer
- ) Internal —/—
- ) External —/—
- ) — externa
endothelium subendothelial elastic lamina elastic lamina Tunica
Blood Vessels- Structure vs Function:
Arteries: elastic to store — and muscular to help —
Arterioles: —/— controls — blood flow
Capillary: — only for —
Venules: High — for —
Veins: Have a large — to store —, under low —, and the valves help —
energy flow Smooth muscle local endothelium exchange permeability inflammation volume blood pressure uni-directional flow
The blood flow from the heart is intermittent, blood flow through tissues is —.
A passive recoil of —/— provides the — and resistance of circulation so stops energy being — too quickly.
continuous
elastic arteries
energy
released
Ventricular Contraction:
- ) Ventricle contracts.
- ) the — valve opens
- ) The — and — expand and store — in the — walls.
Ventricular Relaxation:
- ) Isovolumic — relaxation
- ) — valve shuts
- ) — recoil of arteries sends blood forward into rest of the — system.
semilunar
aorta + arteries, energy, elastic
ventricular
semilunar
elastic
circulatory
Types of capillary: Continuous Found in --- muscle and brain The endothelial lining is --- They have ---/--- between adjacent cells Very tight in BBB
skeletal
intact
tight junctions
Types of capillary: Fenestrated Found in --- and --- The endothelial lining is not very --- It has thin ---, also known as pores. It permits high rate of --- at expense of leakage
kidney intestine intact fenestrations exchange
Type of capillary: Sinusoid Found in --- and ---/--- Has an incomplete --- lining exchange of --- molecules and cells permits maximum opportunity to --- the blood
liver bone marrow endothelial large modify
Fluid exchange in cappilaries driven by forces:
— and — forces act across the capillary —
At the arterial end, the balance promotes —
At the venous end, the balance promotoes —
The net filtration pressure at the arterial end forces molecules — of the capillary (NFP is +ve). The net filtration pressure at the venous end of the capillary pushes molecules — the capillary (NFP is -ve)
NFP = — pressure - — pressure
hydrostatic osmotic walls filtration reabsorption out into Hydrostatic osmotic
Net outflow = Net — - Net —
About - litres a day is collected by —/—
The excess — and — that filter out of the capillary are picked up by the —-/— and returned to circulation
filtration absorption water solutes lymph vessels
Venous Blood Pressure:
The pressure gradient in the venous system is only about – mm Hg.
A muscular ‘pump’ makes contraction of —/— which ‘milks’ blood toward the —.
A respiratory ‘pump’ causes pressure changes in the thorax/abdomen to squeeze/expand major —.
— ensure direction of — toward the —.
20 skeletal muscles heart veins valves blood heart
Factors affecting Mean Arterial Pressure:
Mean arterial blood pressure is determined by:
1.) Volume of —
2.) Effectiveness of a heart as a —
3.) Resistance of — to —/—
4.) Relative — of blood between — and — blood vessels.
1 is determined by fluid — and fluid —
2 is determined by —/— and —/—
3 is determined by — of arterioles
4 is determined by — of veins
Blood pump system blood flow distribution, arterial, venous intake, loss heart rate, stroke volume diameter diameter
Arterioles are the — vessels of the circulation
resistance = 1/r^4
This is determined by:
direct —/—/— response to —
response to local — and circulating —
sympathetic — activity
resistance
smooth muscle cell, stretch
metabolites, hormones
nervous
Adrenal — hormones- noripinephrine + epinephrine cause overall —
ADH causes — when the —/— is very low
Angiotensin II causes intense —
Endothelium-derived factors are —
Nitric oxide has a brief but potent — effect
Inflammatory chemicals such as — and — are potent —
Local metabolites such as CO2 + – all —
medulla vasoconstriction vasoconstriction, blood pressure vasoconstriction vasoconstrictors vasodilation Histamine + kinins vasodilators K+, vasodilate
Sympathetic activity- Baroreceptor reflex:
Impulses travelling along — nerves from — stimulate the —/— centre so sympathetic impulses to the heart will —.
Therefore the diameter of the vessels will — which — the resistance. This has what effect on the blood pressure?
Thus returning the blood pressure to the normal range.
An imbalance such as a stimulus which rises the blood pressure will stiimulate — in the — sinuses and the — arch. The cycle then continues with the impulse coming from the
— to the —/—
afferent baroreceptors cardio-inhibitory decline increase decreases BP decreases baroreceptors carotid aortic baroreceptors cardio-inhibitory centre
Mean Arterial Pressure and Cardiac Output:
Decreased blood pressure activates — centres in the —.
This increases/decreases Parasympathetic centre activity leading to increased —/— and therefore cardiac —.
When the sympathetic centre activity increases in response to decreased Blood pressure, this has the same effect on the heart rate as levels of — will be raised in the blood. This works by increasing the — of cardiac muscle which lowers the end — volume, increasing the — volume and therefore cardiac output.
cardiac medulla decreases heart rate output epinephrine contractility systolic stroke
Cardiac Output and Cardiac Reserve:
Cardiac output is the volume pumped by each — per minute.
CO = Heart rate x Stroke volume
HR is the number of — per minute
SV is the volume of blood pumped out by a — with each
—.
STROKE VOLUME FORMULA:
Cardiac reserve is the difference between — and — CO.
ventricle
beats
ventricle
beat
SV = End diastolic volume - End systolic volume
resting
maximal
Control of Stroke Volume:
The preload is the amount that the ventricles are — prior to —. This is set by —/—/—.
Contractility is the cardiac cell — force from factors other than EDV.
Afterload is the back — exerted by blood in the large — leaving the heart.
stretched systole end diastolic volume contractile pressure arteries
Stroke Volume + Starling’s law of the heart:
The heart is a — pump which attempts to pump all that is returned to it which is called the ‘—/—’.
Greater venous return –> greater filling –> greater stretch –> greater force –> greater stroke — and eventually greater —/—
demand
venous return
volume
cardiac output
Stroke volume + Afterload:
Before the heart can pump blood, the ventricle must expend energy which generates a pressure greater than
— pressure (— pressure)
Some of the work done by the heart muscle is wasted by not pumping blood.
arterial (diastolic)
