W5 - CV System - Textbook Flashcards
What 2 crucial functions does the right side of the heart have?
Receives blood from the body
Pumps blood to lungs
What 2 crucial functions does the left side of the heart have?
Receives O2 blood from lungs
Pumps blood into aorta for distribution through body in systemic circulation
What % of blood returning to the atria flows directly into the ventricles before the atria contract?
~70%
What is it called when there’s a brief interval of rising ventricular tension when the valves remain closed for 0.02 to 0.06s when the heart vol + muscle fibre length remain unchanged?
Isovolumetric contraction period
What is a vessel/tubes resistance inversely proportional to?
The 4th power of its radius
What in the arterioles controls bf to the capillary beds?
Smooth muscle
Calculation for blood pressure
CO x total peripheral resistance
What vessels can be found between the arterioles + the capillaries?
Metarterioles
What happens in phlebitis
Venous wall of varicose veins becomes inflamed + deteriorates.
What can hypertension do when left untreated?
Damages arterial vessels
Leading to arteriosclerosis, heart disease, stroke + kidney failure
Does the bp response to PA vary with the activity mode?
YES
Where do the right + left coronary arteries emerge from?
Upper part of the ascending aorta.
What % of the O2 in the blood in the coronary vessels does the myocardium require?
~70%
Why does the myocardium depend on adequate O2 supply?
Unlike skeletal muscle, it has limited anaerobic energy generating capacity
What are the chest pains called caused by impaired coronary bf?
Angina pectoris
What estimates myocardial workload?
The rate-pressure product
^^ calculated by: HR x systolic bp
What provides energy to maintain myocardial function?
Metabolism of:
Glucose
FAs
Lactate
What does the % myocardial use of macronutrients for energy vary with?
Intensity + duration of PA
Ind training status
What factors regulate HR + the internal diameter of bv?
Neurochemical factors
Order of the transmission of the cardiac impulse
SAN
Atria
AVN
AV bundle (a.k.a bundle of His)
Purkinje fibres
Ventricles
What type of an electrical charge do the outer surface of myocardial cells have?
More +ive than the inside.
What happens upon stimulation prior to contraction of the myocardial cells in relation to the charge of the outside + inside of their cells?
Polarity reverses:
Inside becomes more +ive than its outside.
Then in diastole = Membrane depolarise. to reestablish normal resting membrane pot.
Input from the brain + peripheral NS continually bombards the cardiovascular control centre where?
In the ventrolateral medulla
What does the cardiovascular control centre in the ventrolateral medulla do?
Regulates hearts blood output
+
bloods preferential distribution to tissues.
What does stimulation of the sympathetic cardioaccelerator nerves release?
Epinephrine + norepinephrine (catecholamines)
What do the neurohormones catecholamines do in the sympathetic influence of extrinsic regulation of the HR + circulation ?
Accerelerate SAN depolarisation = ⬆️ HR = Chronotopic effect
+
⬆️ myocardial contractility = inotropic effect
Neural regulation of the CV system during PA
Activation pre-exercise “anticipatory” response
Motor cortex activates central command part of brain = ⬆️ Sympathetic outflow + inhibits parasympathetic activity
Neural regulation of the CV system during PA
Activation during exercise
Sympathetic stimulation from:
- Arterial baroreflexes
- Cardiopulmonary reflexes
- Exercise pressor reflex
Then continues sympathetic adrenergic outflow w/ epinephrine + norepinephrine from the adrenal medulla
Where does the arterial baroreflex come from?
Aortic + carotid arterial mechanoreceptors
Where does the cardiopulmonary reflex come from?
Cardiac mechanoreceptors
Where does the exercise pressor reflex come from?
Skeletal muscle ergoreceptors
What continually modulates medullary activity?
Impulses originating in the brains higher somatomotor central command centre.
What provides the greatest control over exercise HR?
Central command centre
Where do parasympathetic nerve endings concentrate?
Atria
SAN
AVN
Where do the sympathetic fibres supply to?
SAN
AVN
Muscle of atria + ventricles
Where does the cardiovascular centre receive reflex sensory input (feedback) from?
Peripheral receptors in bv, joints + muscles.
What does the sympathetic division of the autonomic nervous system do to the eye?
Dilates the pupil
What does the sympathetic division of the autonomic nervous system do to the lungs?
Relaxes airways
What does the sympathetic division of the autonomic nervous system do to the heart?
Accelerates heart beat
What does the sympathetic division of the autonomic nervous system do to the liver?
Stimulates glucose prod + release
What does the sympathetic division of the autonomic nervous system do to the stomach?
Inhibits digestion
What does the sympathetic division of the autonomic nervous system do to the adrenal gland?
Stimulates secretion of epinephrine + norepinephrine
What does the parasympathetic division of the autonomic nervous system do to the eye?
Constricts pupil
What does the parasympathetic division of the autonomic nervous system do to the lungs ?
Constricts airways
What does the parasympathetic division of the autonomic nervous system do to the heart?
Slows heart beat
What does the parasympathetic division of the autonomic nervous system do to the stomach?
Stimulates digestion
What does the parasympathetic division of the autonomic nervous system do to the pancreas?
Stimulates release of insulin + digestive enzymes
What does the parasympathetic division of the autonomic nervous system do to the small intestine ?
Dilates bv in gut
When does the neural command centre above the medullary region initiate CV changes?
Immediately before + at movement onset.
What does exercise anticipation from higher centres in the brain activate?
Sympathetic neurons in the hypothalamus
What do efferent sympathetic fibres do to the heart?
⬆️ HR
⬆️ myocardial contractility
Dilate coronary arteries
What causes the adrenal medulla to release epinephrine?
Sympathetic nervous stimulation
What does the epinephrine released from the adrenal medulla do?
Accelerates SAN discharge
Dilates coronary vessels
⬆️ myocardial metabolism
What fibres slow HR + conduction velocity using Acetylcholine at the SAN + AVN
Vagus nerve fibres
What are the 3 common methods of measurement to assess the CO of a closed circulatory system in humans?
Direct fick
Indicator dilution
CO2 rebreathing
What 3 physiological mechanisms increase SV during PA?
- Enhanced cardiac filling in diastole, then a more formal systolic contraction.
- Neurohormonal influence involving normal ventricular filling w/ a forceful ejection + emptying during systole
- Training adaptations
3 physiological mechanisms that increase SV during PA
What comes under training adaptations?
⬆️ blood vol
⬇️ resistance
= in peripheral tissues
What does Frank-Starlings law of the heart (a.k.a Starlings law) state?
W/in physiological limits, the force of contraction is directly proportional to the initial length of the muscle fibre.
