12. Chapter 14- Cardiovascular Physiology Flashcards
What does the circulatory system do?
Provides a concentration gradient from the blood to cells for nutrients and in the opposite direction for waste
What are the primary and secondary roles (3 of them) of the circulatory system?
Primary- distribution of gases and other molecules for nutrition, growth and repair, while simultaneously removing cellular wastes
Secondary- chemical signalling to cells by circulating hormones or neurotransmitters
- dissipation of heat by loving heat from core to surface of body
- mediation of inflammatory and host defense responses against invading microorganisms
How was the circulatory system originally thought to be? (The two systems)
Who proved it wrong?
- Venous blood was made in liver and distributed throughout body
- Arteries contained air from lungs and spirits which flow to heart
Tissues were thought to consume all blood delivered to them and liver constantly made new blood
Dr William Harvey showed that the heart pumped more than entire body weight in blood in an hour and there was no way the liver could do that
What were Dr William Harvey’s 2 big discovery’s on the heart?
- Showed the valves of the heart and veins created a one way flow of blood and that veins carried blood back to the heart not limbs
- Showers blood entering the heart from the right side had to be pumped through the lungs before entering the left side of the heart
What are the three types of transport in the circulatory system?
- Materials entering the body
- Materials moved from cell to cell
- Materials leaving the body
Examples on slide 7 Nov 7
What are the two circuits the heart uses to pump blood?
What are the 4 compartments of the heart?
Pulmonary circuit- leaves right side of heart and enters left side and goes to pulmonary capillaries in lungs
Systemic circuit- leaves left side of heart and enters right side
Right atrium, right ventricle, left atrium, left ventricle
Slide 8 Nov 7 (notice the left and right are relative to how the heart would be placed in us)
What are arteries, veins, vena cava, and capillaries
Arteries- carry blood away from heart
Veins- carry blood back to heart
Capillaries- smallest vessels where transport takes place
Vena cava- there is superior vena cava which brings blood into the right atrium from the head brain and arms and the inferior vena cava which brings blood from the trunk, liver, digestive tract, kidneys, pelvis and legs
Slide 9
Study the heart (slide 10 nov 7) and location of the: Superior vena Cana Right pulmonary arteries Right pulmonary veins Inferior vena cava Aorta Left and right atrium Left and right ventricle Septum Left pulmonary arteries Left pulmonary veins Descending Aorta Know where each takes blood on slide 11 nov 7
Systematic veins->Venae cavae->right atrium->right ventricle->pulmonary trunk (artery)->lungs
Pulmonary veins->veins of lungs->left atrium->left ventricle->aorta->all body except lungs (systemic arteries)
How does blood flow through cardiovascular system?
What is driving pressure?
Flow down pressure gradients (high pressure to low pressure)
Initial region of high pressure in cardiovascular system is created by contraction of heart, blood flows out of high region into low pressure vessels
Driving pressure is the high pressure in ventricles
Graph on slide 12 nov 7
How is pressure gradient found?
ΔP=P1-P2
Needs to be positive pressure gradient for fluid to flow through a tube
Size of the pressure gradient determines the flow
Look at examples on slide 14 nov 7
What opposes flow?
What is flow directly proportional to?
What about inversely proportional to?
Resistance
Friction in the walls of a tube
Flow is directly proportional to the fourth power of the vessel radius
When radius of tube decreases, resistance to flow increases
Flow is inversely proportional to the length of the vessel and viscosity of the liquid
Short length tube will have less resistance and more flow
Slides 16 and 17 nov 7
How long does the heart rest between beats?
In one minute of work how much work will the heart perform?
How many times will the heart contract in a 70 year lifetime?
Rests for milliseconds between beats
In one minute heart performs the same work of lifting a five pound weight up 1 foot
In a 70 year life span the heart will contract >2.2 billion times
What is the pericardium?
What is the Hart mainly composed of?
Double walled sac filled with a thin layer of clear pericardial fluid
Lubricates the external surface of the heart as it beats within the sac
The heart itself is mostly composed of myocardium covered by thin inner and outer layers of epithelium and connective tissues
What is the tricuspid valve and the mitral valve?
What are these valves attached by?
What are semilunar valves? (2 types)
Tricuspid valve- right atrium to right ventricle
Mitral valve- left atrium to left ventricle
The atrium-ventricle valves are attached to papillary muscle in each ventricle by chordae tendineae
Slide 22 nov 7
Semilunar valves are one way valves that exist between the ventricle and outflow artery
Left ventricle to aorta- aortic valve
Right ventricle to pulmonary artery- pulmonary valve
Slide 23 nov 7
Slide 24 nov 7
What is the cardiac conduction system? (Cardiac action potential SA node AV node)
The cardiac action potential originates in a group of cells in the SA node (pacemaker) then spreads through network of autorhythmic cells (these set heart rate)
The AV node and purkinje fibres have slower pacemaker activity over ridden by SA node
SA node->internodal pathways->AV mode->AV bundle (bundle of His)->bundle branches->purkinje fibres
Slide 13 Nov 9
What is atrial conduction and it’s four conduction bundles?
Backmans bundle- conducts action potential from SA pacemaker into left atrium causing contraction
Anterior, middle, and posterior intermodal pathways- conduct the action potential from SA node to AV node, depolarizing right atrial muscle along the way
Slide 15 Nov 9
What is ventricular conduction?
Layer of connective tissue prevents conduction directly from atria to ventricle
- conduction slows through AV node to allow blood from atria to empty in to ventricles, depolarization proceeds through the septum to the apex, then spreads up walls of the ventricles from apex to bad
Slide 16 nov 9
What happens if electrical activity cannot be transferred from the atria to ventricles?
Complete conduction block is caused by damage in conduction pathway
Ex: block at bundle of His results in complete dissociation between the atria and ventricles
Sa node continues to be a pacemaker for atria, but electrical activity does not make it to the ventricles so purkinje fibers take over as pacemakers for ventricles
THIS REQUIRES ARTIFICIAL PACEMAKERS
What is Howard deflection and downward deflection of ECG?
Upward deflection- electrical activity of the heart is moving towards positive electrode of lead
Downward deflection- electrical activity moving away from a positive electrode
No deflection is when electrical activity moves perpendicular to axis of electrodes
Graph on slide 7 Nov 19
Picture on slide 6 Nov 19
What are P waves, P-Q (or P-R) segments, Q waves, and R waves, S waves, S-T segments, and T waves?
Slide 10-11 nov 19 P wave- atrial depolarization P-R segment- conduction through AV node and AV bundle QRS complex- ventricular depolarization T wave- ventricular repolarization
2/3 to 3/4 of ventricle walls depolarize in R wave, rest is done in S wave
What are arrhythmia, tachycardia, and bradycardia?
What are premature ventricular contractions?
Arrhythmia- abnormal rhythm of heat beat
Tachycardia- rapid heart rate
Bradycardia- slow heart rate
Premature ventricular contractions are when purkinje fibres randomly kick in as pacemaker, can be do to insufficient oxygen to myocardium
What are the five stages of the cardiac cycle?
One complete contraction and relaxation (QRS Complex)
Diastole- cardiac muscle relax
Systole- cardiac muscle contracts
1. Heart at rest (atrial and ventricular diastole, late diastole)
2. Completion of ventricular filling (atrial systole)
3. Early ventricular contraction (isovolumetric ventricular contraction)
4. The heart pumps (ventricular ejection)
5. Ventricular relaxation (isovolumetric ventricular relaxation, early diastole)
Slides 17-21 nov 19
What is end diastolic volume (EDV), end systolic volume (ESV), stoke volume (SV), and cardiac output (CO)?
EDV- max volume in ventricle ~135ml
ESV- min blood volume in ventricles after ventricular contraction ~65ml
SV- amount of blood ejected in singular ventricle contraction 135-65=70ml
CO- total blood flow from one ventricle in a given time period CO=Heart rate x SV in L/beat
Slide 7-9 nov 21
Can modify cardiac output by adjusting heart rate slide 10 nov 21
What are the 2 factors that determine the amount of force generated by the heart?
- The contractility of the heart- ability of cardiac muscle fibres to contract at any given fibre length as a function of Ca entering and interacting with contractile filaments
- Length of muscle fibres at beginning of contraction- determined by volume of blood in ventricle at beginning of contraction
What are positive and negative inotropic effects and what’s an inotropic agent?
Positive inotropic effect- chemicals increasing contractility
Negative inotropic effect- chemicals decreasing contractility
Inotropic agents- any chemical that affects contractility
Catecholamines (norepinephrine and epinephrine) are positive inotropic agents
Graph on slide 12-13 nov 21
What does increasing sarcomere length do to force on contraction?
Increases force of contraction
Raising sarcomere length increases Ca sensitivity of myofilaments since stretched sarcomere has decreases diameter which reduces distance Ca needs to diffuse
It also puts tension on stretch activated Ca channels
What is the frank starling law of the heart?
What is Preload and afterload of heart?
Amount of force developed by cardiac muscle of a ventricle depends on initial stretch of the ventricle walls
The degree of myocardial stretch prior to contraction is known as preload of the heart
Afterload is end load against which heart contracts to eject blood (determined by pressure in outflow artery prior to contraction
What are 3 factors affecting venous return?
- Skeletal muscle pump- Skeletal muscle activity compresses veins pushing blood back to heart
- Respiratory pump- chest expands during inspiration creating pressure in thoracic cavity that draws blood into vena cava
- Sympathetic constriction of veins- decreases their volume and brings blood back to heart
Study structure of arteries, arterioles, capillarys, venules, and veins on slide 6 Nov 23
Okay
What makes up microcirculation?
Aterioles, capillaries, and venules
Capillaries are smallest in cardiovascular system (most of exchanges between blood and interstitial fluid occurs here)
Metarterioles are bypass vessels across the microcirculation
Slide 8 nov 23
What are the 3 types of capillaries?
Continuous capillary- most common, thicker no fenestrations to allow transport through them, only allow passage of water through intracellular junctions
Fenestrated capillary- thin endorphins cells perforated with fenestrations, small molecule passage
Discontinuous capillary- lack a basal membrane, large open fenestrations and gals between endothelial cells
Structures on slide 10 Nov 23
What are the 3 methods of transport in capillaries?
Transcellular transport- diffusion across endothelial cell membrane
Paracellular transport- diffusion through interendothelial junctions, pores, and fenestrations
Trancytosis- combo of endocystosis, vesicular transport, and exocytosis
Compare veins and arteries on slide 12 nov 23
What is the formation of new blood vessels called?
Angiogenesis
What is ventricular contraction and ventricular relaxation?
VC- contraction of ventricles pushes blood into elastic arteries, causing them to stretch, increased amount of flow
VR- elastic recoil in the arteries maintains driving pressure during ventricular diastole, maintains some pressure when relaxing
How is pulse pressure (blood pressure) determined?
What is mean arterial blood pressure?
Aortic pressure highest during ventricular contraction- systolic pressure= 120mmHg
Aortic pressure lowest during ventricular relaxation- diastolic pressure= 80mmHg
Difference between systolic and diastolic is the pulse pressure
Mean arterial is the single value we look at for blood pressure, it is not average since equal times are not spent in diastolic and systolic
Is cardiac output times peripheral resistance
Slide 6 Nov 26
What is hypotension and hypertension?
What are the stages and systolic and diastolic pressure for them?
Hypotension- blood pressure falls too low (gravity can not let blood flow up to brain if falls too low)
Hypertension- blood pressure is chronically elevated (causes vessel walls to be weakened or rupture or leak leads to cerebral hemorrhage)
Stage 1- 130-139 systolic 80-89 diastolic
Stage 2- 140+ systolic 90+ diastolic
Crisis- 180+ systolic 120+ diastolic
What are the 4 things that determine mean arterial blood pressure?
How is changes in blood volume (that change blood pressure) resolved?
Blood volume (fluid intake and fluid loss)
Effectiveness of heart as a pump (heart rate and stroke volume)
Resistance of system to blood flow (diameter of arterioles)
Relative distribution of blood between arterial and venous blood vessels (diameter of veins)
Resolved by kidneys slowly and resolved by cardiovascular system quickly
How are capillaries and veins resistances different in terms of organization of circuit (series and parallel)?
Veins in series
Capillaries in parallel
Parallel circuits have less resistance than series
Slide 14 Nov 26
What is myogenic autoregulation?
What alters vascular smooth muscle?
Vascular smooth muscle has the ability to regulate its own state of contraction
Increase in blood pressure causes vascular smooth muscle in wall of arteriole to stretch which then causes vascular smooth muscle to contract leading to vasoconstriction
Paracrines alter vascular smooth muscle
What are the 3 types of local and systematic control mechanisms that alter vascular smooth muscle which changes the radius of vessels which influences resistance?
- Local control of arteriolar resistance- matches tissue blood flow to the metabolic needs of the tissue
- Sympathetic reflexes- mediated by CNS maintain mean arterial pressure and govern blood distribution for homeostatic needs
Slide 20 Nov 26 - Hormones- influence blood pressure by acting directly on the arterioles and by altering autonomic reflex control
What maintains adequate blood flow to the brain and heart by maintaining sufficient mean arterial pressure?
Medullary cardiovascular control center
What is the baroreceptor reflex?
Primary reflex pathway for homeostatic control of mean arterial blood pressure
They are tonically active stretch sensitive mechanoreceptors that are on the aorta and corotid artery
Orthostatic hypertension triggers this (whenever you stand up out of bed quick heart beat falls from 5L/min to 3L/min)
Slide 9-12 Nov 28
What are peripheral chemoreceptors?
What can alter cardiovascular function in response to emotional stress?
Located on aortic arch and carotid artery
Sense alterations in blood gas’s concentrations
Send this info back to the cardiovascular control centre which then changes autonomic output to return blood gas levels to normal value
Hypothalamus can alter cardiovascular function in response to emotional stress
What is bulk flow in capillaries?
What is absorption and filtration?
The mass movement of fluid as the result of hydrostatic (moving fluid out) or osmotic pressure gradients (draws fluid back into capillaries)
Absorption is fluid moving into capillaries
Filtration is fluid moving out of capillaries
Pressure of filtration is hydrostatic pressure (Ph)
Pressure of absorption is oncotic pressure (π)
Created by plasma proteins
Slide 5 Nov 30
What are lymphatics in the cardio vascular system?
Lymphatic vessels assist the cardiovascular system with returning fluid and proteins lost through capillaries
Slide 7 Nov 30
