Week 5 - Revision Cardiac output and BP Flashcards
Cardiac output
the volume of blood leaving the heart each minute = Heart Rate (bpm) x stroke volume
Heart rate
number of heart beats per minute
Stroke volume
volume of blood leave the blood with each beat
Bradycardia
slow resting heart rate (<60bpm)
Tachycardia
rapid resting heart rate (<100bpm)
Systolic blood pressure
force exerted by circulating blood on the walls of the arteries during systole
Diastolic blood pressure
force exerted by circulating blood on the walls of the arteries during diastole
Pulse pressure
SBP minus DBP
Basal HR
HR while at rest in a neutrally
temperate environment, digestive
system is inactive (about 12
hours)
Resting HR
Awake but lying down and not
having immediately exerted
themselves
Average 60-80 beats per minute (bpm)
Pre-exercise HR
Physiological anticipation of
exercise
Increased sympathetic neural
drive
Steady State HR
Work rate is held constant at submaximal
levels of exercise.
Maximum HR
Highest HR value achieved in an all
out effort to the point of
exhaustion.
220 - age
How much does metabolic rate increase during activity?
10-20x
Intrinsic control of heart rate (4) conductions
SA node in right atrium through internodal pathways to AV node in right atrium, through Bundle of His between ventricles, it parts to left and right bundle where purkinje fibers break off and innervate the ventricles
What extrinsic influences have a direct change on the intrinsic control of the heart
Direct nerve supply to myocardium, hormones in the blood, central nervous system Somatomotor regions
What region of the brain is the cardiovascular control centre?
Ventrolateral Medulla
What does the Ventrolateral Medulla regulate
*Regulates heart’s output & blood distribution
*Continually evaluates and processes sensory input from the brain and peripheral NS
*Modulates sympathetic and parasympathetic nervous activity
Extrinsic influence - parasympathetic
Slows heart rate through vagus nerve cell bodies which originate in cardio inhibitory centre
Extrinsic influence - sympathetic
Increases heart rate by increasing activity of the SA node and increase atrial and ventricular contractile force and HR
Extrinsic influence - What hormones have an extrinsic influence on the cardiovascular system and where is this from?
Adrenaline and noradrenaline from the adrenal medulla
Difference between Parasympathetic and Sympathetic nerve endings in the heart
Parasympathetic concentrate in the L & R atria, including SA and AV nodes.
Sympathetic fibers supply SA, AV nodes and the muscle of the atria and ventricles.
Where is the adrenal medulla located? And how does it send it’s hormones through the body? Fast or slow acting?
On the apex of the kidney and these hormones are released through the blood.
Slow acting.
Noradrenaline effects
*Increased contractility
*Increased relaxation rate
*Increased heart rate
*Increased conduction velocity
Noradrenaline effects during exercise
*blood shunted from the skin & viscera to the skeletal
muscles, coronary arteries, liver, & brain
*Vasoconstriction
* increased blood sugar
*increased metabolic rate
*bronchi dilate
*pupils dilate
*hair stands on end (“gooseflesh” in humans)
How is BP determined?
Volume of blood pumped and the resistance of arterial walls against the blood.
E.g. vasoconstriction = higher resistance, higher BP
Autonomic nervous system regulates blood vessels how?
Vasodilation of arterioles to exercising muscles
Vasoconstriction of arterioles to non exercising muscles
Vasoconstriction of venous vasculature
