hypertension Flashcards
blood vessel types (5)
artery, arteriole, capillary, venule, vein
artery characteristics
muscular and elastic
arteriole characteristics
muscular
capillary characteristics
small diameter, thin-walled
venule characteristics
slightly muscular
vessel wall layers (5)
lumen, tunica intima, tunica media, tunica externa, external elastic lamina, tunic adventitia
heart rate
number of times the heart beats per minute
normal heart rate
60-85 bpm
stroke volume
volume of blood ejected from the heart in one beat
normal stroke volume
70 ml
cardiac output
volume of blood ejected form the heart per minute
cardiac output calculation
heart rate x stroke volume
normal cardiac output
5 litres
peripheral resistance
resistance that must be overcome for blood to flow in the circulatory system
what contributes to peripheral resistance?
arterioles (smooth muscle tone), capillaries and venules
mean arterial blood pressure
average pressure exerted by the blood onto the walls of major arteries
mean arterial blood pressure calculation
cardiac output x total peripheral resistance
normal mean arterial blood pressure
<107 mmHg
factors affecting MABP
stroke volume, ventricular contractile force, artery elasticity, peripheral resistance
systolic blood pressure
peak arterial pressure during heart contraction
diastolic blood pressure
minimal arterial pressure during heart relaxation
hypertension
consistently high blood pressure causing damage to endothelial cells and later haemorrhages
hypertension BP
> 140/90 mmHg
hypotension
consistently low blood pressure
hypotension BP
<90/60 mmHg
hypotension causes
dehydration, heart failure, MI, arrhythmia, shock
diurnal fluctuations
changes in BP during the day
atrial natriuretic peptide
released by atrial myocytes to decrease ADH secretion
antidiuretic hormone
released by pituitary gland cells causing decreased sodium and water excretion and therefore vasoconstriction and increased BP
adrenaline
released by chromaffin cells in the adrenal medulla causing increased heart rate and ventricular contractile force and therefore increased cardiac output
renin
released by juxtaglomerular cells and cleaves angiotensinogen to form angiotensin I
angiotensin converts enzyme
cleaves inactive angiotensin I to form angiotensin II
angiotensin II
acts as potent vasoconstrictor by acting on AT receptors to stimulate ADH and aldosterone secretion
aldosterone
released by the adrenal cortex causing increased sodium and water reabsorption
primary aldosteronism (Conn’s syndrome)
high aldosterone caused by tumours or adrenal gland hyperplasia leading to polydipsia, polyuria and persistent hypokalaemia
primary hypertension
95% of cases, no clear cause
secondary hypertension
5% of cases, caused by other underlying condition
elevated BP
<130/80 mmHg
stage I hypertension
<140/90 mmHg
stage II hypertension
> 140/90 mmHg
stage III or crisis hypertension
> 180/120 mmHg
modifiable risk factors
exercise, weight, smoking, alcohol, diet/diabetes, stress, sleep
non-modifiable risk factors
renovascular disease, endocrine disorders, neurological disorders, aortic diseases, pregnancy conditions, substances, sleep apnea
secondary hypertension causes
renovascular disease, endocrine disorders, Cushing’s disease, aortic diseases, pregnancy, sympathomimetics, steroids, NSAIDs, alcohol
