L11-L12 Flashcards
What are the three simple cardiovascular components?
- Heart
- Blood
- Blood vessels
What are the three ways the cardiovascular system transports material within the body? Give an example of each.
- From external environment (nutrients, water, gas )
- Materials between cells (antibodies, hormones, immune cells)
- Waste eliminated by cells (Co2, Heat, waste)
Name the pathway of vessels towards to heart.
Veins—> Venules—>Capillaries—>Arterioles—> Arteries—> Heart
What are the functions of these parts of the heart?
Septum
Atriums
Ventricles
Septum- separates the two halves of the heart
Atriums- receives blood returning to heart
Ventricles- pumps blood out of the heart
What are the four components of blood?
- Erythrocytes= reds blood cells
- Leukocytes= white blood cells
- Platelets
- Plasma
What is the cardiovascular system?
This is a closed loop system that flows through pulmonary and systemic circulations simultaneously
What is the pulmonary circulation portion of the body? What side is it supplied by and where does it go?
The pulmonary circulation is supplied by the right side of the heart, vessels go from the heart to the lungs and lungs to heart. This mainly pumps deoxygenated blood to become oxygenated.
What is the systemic circulation portion of the body? What side is it supplied by and where does it go?
This is supplied by the left side of the heart, vessels from the heart to systemic tissues and tissues to heart. This usually carries oxygenated blood to tissues to deliver, then transports deoxygenated blood back to heart.
Blood flow is due to liquids moving from ____ to ____ pressure regions
High, low
What does the pressure gradient mean (ΔP)
This is the difference in pressure between two regions since blood flows out of the heart (high pressure) into closed loop of vessels (low pressure)
What are the two components to fluid in motion
Dynamic flowing components: component that represents the kinetic energy of the system
Lateral components: this is hydrostatic pressure that is exerted by a fluid not in motion
The pressure of a fluid in motion ______ as distance increase. Pressure is also lost as blood moves through vessels due to______
Decreases, friction
Blood leaves the heart to vessels via _____ pressure since contraction of the heart creates pressure without changing volume
Driving
If blood vessels____ then blood pressure decreases
If blood vessels____ then blood pressure increases
Dilate, constrict
The higher the pressure gradient, the ____ fluid flow. Why is this?
Greater, this is due to fluid flow being proportional to pressure gradient
What is the law of bulk flow? What do each constants mean?
F= ΔP/R
F= flow, the volume of fluid that moves past a given point per unit of time
ΔP= pressure gradient
R= resistance (due to friction)
What is poiseuilles law? What do the constants mean?
R=8Lη/πr ⁴
R= resistance L= length of tube η= viscosity of tube r= radius of tide (has the greatest effect)
What is the velocity of flow? What is the formula? What do the constants mean?
This is the distance a fixed volume of blood can travel in a given period. The formula is V=Q/A
Q= flow rate A= cross sectional area
What is Mean Arterial Pressure?
This is a the primary driving force of blood, pressure reserved in arteries during relaxation.
Describe the following:
Pericardium
Epicardium
Myocardium
Endocardium
Pericardium- out layer, covers the heart in a sac
Epicardium- the outermost layer of the heart, external membrane
Myocardium- cardiac muscles (majority of heart is myocardium)
Endocardium- endothelial cells, extend through entire system. Most inner part of heart
Pathway of deoxygenated blood starting with vena cava
Vena cava—> right atrium—> right ventricle—> pulmonary trunks
Pathways of oxygenated blood starting with pulmonary veins
Pulmonary veins—>left atrium—>left ventricle—>aorta
What are the purpose of heart valves?
To ensure there is one flow direction of blood from the heart
Where are the AV valves located? What are the AV valves?
The AV valves are located between atria and ventricles. The AV valves consist of:
Bicuspid valve: left side
tricuspid valve: right side
____ _______ prevents eversion during ventricular contraction
Chordae tendenae
Where are the semilunar valves positioned? What are the names of these valves?
The semilunar valves are between ventricles and arteries. The names and positions of these are:
Aortic valve= left side
Pulmonary valve= right side
What are autorhythmic cells?
These are pacemaker cells which signal for contractions. Smaller and fewer contractions fibres compared to contractile cells. These don’t have organized sarcomeres.
What are contractile cells?
These are striated fibres organized in sarcomere
Six difference between cardiac and skeletal muscle fibres
- Smaller, single nucleus per fibre
- Branch and join neighbouring cells through inter-calculated disks
- Gap junctions
- T-tubules are larger and branch
- SR is smaller
- Mitochondria occupies 1/3rd of the cell
Six steps for E-C coupling within cardiac cells
- AP starts with pacemaker cells
- Voltage gated Ca+ channels open with RyR receptors in SR due to Ca+ influx
- Ca+ spark— summed spark creates Ca+ signal
- Calcium binds to troponin
- cross-bridge cycle
- Relaxation phase
What is pacemaker potential? Explain details on how it works.
This is an unstable membrane potential. Pacemaker potential gradually becomes less negative until ti reaches a threshold triggering an AP.
Explain the conduction pathways of the heart
- SA node depolarizes
- Electrical activity goes to AV node via internodal pathways
- Depolarization spreads down atria
- Depolarization moves through ventricular system to apex
- Depolarization waves spread upwards from apex
What is an ECG? What does it show?
Electrocardiograph, this shows electrical activity generated by all cells. Not the same as AP
With respect to an ECG, what do these waves mean?
P waves
QRS complex
T waves
P waves- atria depolarization
QRS complex- ventricular depolarization and atrial repolarization
T waves- ventricular repolarization
What do these segments mean?
P-R segment
T-P segment
P-R segment= AV node delay
T-P segment= Ventricular and atrial relation
Pathway of polarization and contractions in relation to ECG. Start with atrial depolarization at P wave.
ECG begins with atrial depolarization at the P wave, after the P wave there is atrial contraction. The P-R electrical segment goes through AV node and through QRS segment while atrial repolarization and ventricular depolarization occur. At the end of QRS phase, ventricular contraction occurs then T wave indicates ventricular repolarization.
Explain the terms diastole and systole
Diastole= relaxation of the heart Systole= contraction of the heart
Explain the five phases of the cardiac cycle and details of each
- The heart at rest— atrial and ventricular diastole:
- atria are filling up with blood from veins
- AV valves open up—> ventricles begins filling up - Ventricular filling— atrial systole
- atrium contract
- remaining blood is forced out of atrium (20%) and pushes into ventricles
- EDV at end of ventricle relaxation - Early ventricular contraction and first sound
- AV valve closes, “lub” sound is made
- isovolumetric contraction (no blood in or out)
- increase pressure due to ventricular contraction, atrial diastole - Heart pumps— ventricular ejection
- semilunar valves open, blood ejected into arteries
- ESV is ventricles at end of ventricular contraction - Ventricular relaxation and second sound
- blood starts to flow back to heart so semilunar valves close “dub” sound
- ventricles relax, pressure drops, AV valves open when ventricular pressure drops below atrial
What is stroke volume? What is the formula? What is the average stroke volume?
Stoke volume is the volume of the blood before contraction minus volume of blood after. The average is around 70ml
SV=EDV-ESV
What is cardiac output? What is this formula? Average CO?
Cardiac output is the volume of blood pumped by one ventricle in a given period of time. Average CO is 5L/min
CO= HRxSV
Explain the parasympathetic effects of cardiac muscles
Decrease heart rate (muscarnic receptors of auto-rhythmic cells effect the following)
- K+ permeability (pacemaker begins at lower value) increases
- Ca+ permeability decreases
- slow rate of pacemaker depolarization
Explain the sympathetic effects of cardiac muscles
increases heart rate, Beta 1 adrenergic receptors on the autorhythmic cells elicit the follow responses:
- Na+ and Ca+ permeability increases
- increases rate of pacemaker depolarization
What is contractility?
Contractility is the ability of a cardiac muscle fibre to contract to any given fibre length
What is the length tension relationship determined by?
This is determined by the volume of blood at the beginning of contraction
What is the degree of stretch called?
Pre-load
Explain frank starling law.
Stroke volume is proportional to EDV
End Diastolic volume is determined by venous return, which is affected by: (three things)
- Skeletal muscle pump
- Respiratory pump
- Sympathetic innervation of veins
What is afterload?
Afterload is EDV and atrial resistance during ventricular contraction
What is the ejection fraction?
Percentage of EDV ejected with one contraction stroke volume/ EDV
