Blood pressure Flashcards
Define blood pressure
Its a measurement of the force exerted by the blood circulating in the arteries.
What factors regulate blood pressure
Blood volume
Resistance to blood flow- lumen diameter, viscosity, blood vessel length and resistance.
Pressure difference
Define blood volume
Can increase via water retention
Can decrease via hemorrage will decrease BP
What causes resistance to blood flow.
lumen diameter
viscosity
blood vessel length
Resistance
What is pressure difference
Blood pressure is highest in the aorta and zero in the great veins
What is blood volume regualtion
blood volume is directly related to blood pressure and can control blood volume.
Increasing blood volume increases venous return of blood to the heart thus stroke volume will increase.
What are the physiological mechanisms regulating BP
Cardiovascular center
Neural baroreceptors and chemoreceptors
Hormones
Autoregulation
What is function of the cardiovascular centre CV centre
Groups of neurones scattered in medulla oblongata
regulates heart rate stroke volume and blood vessel diameter
What are the components of the CV centre
Cardio-accelerator centre
cardio- inhibitory centre
Vasomotor centre
Define cardio-accelerator centre
A group of neurones that regulate heart rate and stroke volume via sympathetic nerves
Define cardio-inhibitory centre
S group of neurones that regulate heart rate and stroke volume via parasympathetic nerves
Define vasomotor centre
A group of neurones that regulate blood vessel diameter via sympathetic nerves.
Define baroreceptors
Found in the aorta and carotid arteries.
Arterial pressure either falls or rises which os relayed from the medullary cardiovascular centre.
What does a rise in BP do to nerves.
Rise in BP- Sympathetic outflow is decreased and parasympathetic outflow increases.
Fall in BP- Sympathetic outflow is increases and parasympathetic outflow decreases.
Define chemoreceptors.
Monitor the changes in blood acidity
The CV centre sends impulses to the heart via sympathetic nerves which increases heart rate and force of contraction
Define the brain bridge reflex
Monitors increase and decrease in venous return.
What hormones that increase blood pressure
Angiotensin 2
ADH
Aldosterone
Define angiotensin 2
Found in the blood plasma
Enzyme renin converts angiotensin 1 to angiotensin 2.
Causes vasoconstriction of arterioles.
Stimulates adrenal cortex to secrete aldosterone a hormone that increases in rate reabsorption by the kidneys. increasing blood volume.
Define ADH
Produced by neurones in the supra optic and para ventricular nuclei of the hypothalamus in response to low blood volume.
How is ADH released
Axon terminals in the posterior pituitary gland.
What does ADH do
Increases water re absorption by the kidneys increasing blood volume.
What is aldesterone
Secreted by adrenal cortex in response to decrease plasma sodium, increased plasma potassium
Increases water re absorption by the kidneys increasing blood volume
What hormones that decreased blood pressure
Atrial natriuretic peptide
Histamine
Describe ANP
Secreted by the heart in response to the to the stretching of cardiac muscles fibres.
Causing vasodilation of arterioles
Decreases water reabsorption by the kidneys, decreasing blood volume
Inhinits the secretion of aldosterone and activation 2
