Module 4 Flashcards
What is the formula for cardiac output and its definition
Cardiac output: the amount of blood volume pumped by the heart in one minute
Q = SV x HR
What is the anatomy of the heart? Draw out
What is the right side of the heart do?
Receives blood returning from elsewhere in the body. Pumps blood to the lungs through a pulmonary circulation
What does the left side of the heart do?
Receives oxygen rich blood from the lungs. Pumps oxygenated blood to the rest of the body
Define artery
Artery: high-pressure tubing that propels oxygen rich blood to tissues. comprised of layers of connective tissue and smooth muscle
Why does no gas exchange occur between arterial blood and surrounding tissues?
Because the walls of the arteries are too thick
Define precapillary sphincter
Precapillary sphincter: a ring of smooth muscle that encircles the capillary at its origin and controls its diameter
Describe the constriction and relaxation of the sphincter
Constriction and relaxation provide a means for blood flow regulation to meet metabolic requirements. One in 30 capillaries are open in the muscle at rest
What two factors trigger precapillary sphincter relaxation (dilation)
- Driving force of increased local BP (plus intrinsic neural control)
- Local metabolites produced in exercise (lactate, Pyruvate, ketones, glycerol etc)
What happens to the flow resistance when the radius of a vessel decreases by half
Increases by 16
Describe veins
Veins are not as muscular as arteries, and prevent backflow. Eventually reach the vena cava to empty into the right atrium.
What is the largest vein in the body
Inferior vena cava
Describe the three different blood pressures
- Systolic blood pressure. Blood pressure during left ventricular contraction. Estimates the work of the heart against of arterial walls
- Diastolic blood pressure. Blood pressure during cardiac relaxation or diastole. With high peripheral resistance pressure will remain high for longer
- Mean arterial pressure. Slightly lower than the actual average pressure, accounts for the fact that the heart remains in relaxation for longer
What is the formula for mean arterial pressure
Map = diastolic BP + [(systolic minus diastolic BP) / three]
What factors affect mean arterial pressure
Increased muscle force cardiac output or vasoconstriction (diameter) all increase mean arterial pressure

What happens to blood pressure during exercise
Systolic BP will have a sharp increase followed by slight increase
Diastolic BP it will remain very level with minor decreases
Describe the normal route for impulse transmission within the myocardium
- The impulse will originate from the Sino atrial node located in the right atrium, and spread across the atria contract them
- The impulse then passes to the AV node travels along the atrioventricular bundle into the right and left cruise, spreads into the ventricles and contracts them
- Dissipation of the impulse will cause the atria and ventricles to relax
Describe the ECG Waze and it’s different components
- Atrial depolarization - P-wave: depolarization of the atria before atria contract
- Ventricular depolarization – QRS wave: signals electrical changes from ventricular depolarization before ventricles contract
- Ventricular repolarization – T wave: represents ventricular repolarization that occurs during ventricular diastole
What portion of the normal ECG would tell us our heart rate
The peak of the R-wave
What can be an a indication of a past heart attack or even a current one
B-flat portion between the QRS wave and the T-wave, if depressed or increase, indicates a history of heart attack or even a current one
What is the distribution of sympathetic and parasympathetic nerve fibres with the heart
- parasympathetic nerve endings concentrate in the atria including the SA and AV nodes
-  sympathetic nerve fibres supply the SA and AV nodes, plus the muscle of the atria and ventricles
What causes the release of epinephrine and norepinephrine, and what kind of effects do they have on the heart
Stimulation of sympathetic cardio accelerated nerves release epinephrine (vasoconstriction except for coronary arteries and chronotropic: increase heart rate) and norepinephrine (Inotropic: increases contractility)
Define Adrenergic
Relating to or denoting nerve cells in which Epinephrine, norepinephrine or noradrenalin acts as a neurotransmitter
How does sympathetic ns influence dilation?
Dilation of blood vessels under decreased adrenergic (sympathetic) influence
Symp activity typically causes constriction, but it can balance with parasympathetic so that it shunts towards active muscles
What do you the sympathetic and parasympathetic divisions do to the heart/body
Heart: parasympathetic decreases heart rate, sympathetic increases heart rate and contraction
Body: parasympathetic relaxes muscles, sympathetic contracts muscles
How does the parasympathetic division decrease heart rate
- Neurons release acetylcholine which delays sinoatrial discharge, which slows heart rate
- at the beginning of low exercise heart rate increases largely due to the inhibition of parasympathetic stimulation, without any additional sympathetic drive
What is the cause of bradycardia
Results from stimulation of the vagus nerve from the medulla cardio inhibitory centre
Describe the innervation of parasympathetic and sympathetic division when in strenuous exercise
Additional parasympathetic inhibition and direct activation of sympathetic cardio acceleratory nerves
When measuring arterial oxygen saturation would it matter if you sampled blood from the arteries supply in active vs inactive muscle?
No! Oxygenation of blood happens at the lungs and does not happen at the arteries. It would matter if you’re measuring venous carbon dioxide saturation. If you measure the saturation of the veins in active vs inactive muscle it will have very different values.
How would the heart behave without chemical or neural inputs?
The heart will have a resting heart rate of a roughly 100 bpm. If we kill the sino atrial node, it would still beat but would be much slower. Without chemical or neural inputs the heart rate will not change
Why does blood pressure increase during exercise? How?
We vasodilate to allow for more blood flow. when the heart is relaxed, it means that our diastolic blood pressure does not change by much. When we exercise, our cardiac output goes up to allow more oxygen to get to the muscle.
Explain how each branch of the autonomic nervous system can increase heart rate
Sympathetic increases heart rate and contraction
Parasympathetic Decreases heart rate
 What are some of the neural mechanisms for cardiovascular regulation?
- To the higher brain
- aortic and carotid arterial mechano receptors (arterial baroreflexes)
- cardiac mechano-ceptors (cardio pulmonary reflexes)
- Skeletal muscle (exercise precursor reflex) - efferent
- Heart chronotropic or inotropic function
- Active or inactive Skeletal muscle contraction
- kidney and splenic bed vasoconstriction
 What are some of the neural mechanisms for cardiovascular regulation?
- To the higher brain
- aortic and carotid arterial McCann over receptors (arterial baroreflexes)
- cardiac mechano-ceptors (cardio pulmonary reflexes)
- Skeletal muscle (exercise precursor reflex) - efferent
- Heart chronotropic or inotropic function
- Active or inactive Skeletal muscle contraction
- kidney and splenic bed vasoconstriction