Short term physiological responses to a challenge Flashcards
Describe capillaries at rest
Mostly closed, small amounts of blood going through them
What happens to the capillaries during exercise?
Metabolites build up causing vasodilation and more capillaries are therefore required
What is the equation for Total Peripheral Resistance?
R= 8Ln/pi x R4 R= resistance to flow L= length of vessel N= viscosity R= radius of vessel
Why does cardiac output increase?
Caused by increased stroke volume, increased heart rate (Starling mechanism- increased flow to the heart, puts stretch on muscle cells, lined up for maximal efficiency, and can increase blood flow)
What is Starling’s Law?
The stroke volume of the heart increases in response to an increase in the volume of blood filling the heart (the end diastolic volume) when all other factors remain constant.
How do you calculate maximum heart rate?
220-age
Signs of haemorrhage?
Pallor- due to peripheral vasoconstrictions
Cold skin- due to peripheral vasoconstrictions
Rapid Pulse- circulating adrenaline and noradrenaline
Sweating- counter productive,
Confusion
Increased Respiratory rate
How do you calculate Mean Arterial Pressure (MAP)?
MAP= DBP + 1/3 (SBP - DBP)
How do you calculate Blood pressure (BP)?
BP= TPR x CO
How do you calculate Cardiac output (CO) from the Frank-Starling mechanism?
CO= SV x HR
What effect do beta1 adrenergic receptors have on the heart?
Increase heart rate and stroke volume
What effect do alpha1 adrenergic receptors have on veins?
Venoconstriction
What effect does alpha1 adrenergic receptors have on visceral vessels?
Vasoconstriction of visceral vessels
What is the Ach Nicotinic receptor?
Adrenaline released from adrenal medulla
How do you control the respiratory response?
Central Command (feedforward) Peripheral Chemoceptors Increased Body Temperature Neural Input from Limbs Secretion of adrenaline & noradrenaline
