Cardiovascular diseases Flashcards
(46 cards)
How do you calculate mean arterial blood pressure?
CO* Peripheral resistance
What are 2 causes of increased blood pressure?
- Increased CO (HR X SV)
- Increased peripheral resistance (reduced vessel diameter and increased viscosity)
What is peripheral resistance?
Opposition to flow that blood encounters in vessels away from the heart
What are 2 variables that effect resistance?
- Blood viscosity
- Vessel radius (most powerful)
What elevates blood viscosity?
-RBC count and albumin concentration
What are the two types of baroreceptors?
Arterial (HP) baroreceptors
-located in carotid sinus + aortic arch (fast response)
Low pressure baroreceptors
-walls of major veins + right atrium (slower response)
What do LP baroreceptors do?
- Detect a blood volume decrease
- Cause afferent signals to be sent to hypothalamus
- ADH is released (water reabsorbed)
What does the stretching of atrial receptors (volume increase) do?
Increases secretion of atrial natriuretic peptide (ANP) which promotes increased water and sodium excretion via urine
What does the bainbridge reflex do?
Cause an increase in the heart rate (decreases pressure in S + I venae cavae)
How do the kidneys respond to low pressure baroreceptors
-Secreting excess salt and water via urination
What happens if the GFR falls
- Macula relaxes
- Macula densa stimulates JG cells
- Blood flow increases
- Release of renin from juxtaglomerular cells
What happens if the GFR rises
- More NaCl is reabsorbed
- Reduced paracrine stimulation of JG cells
- JG contract (reduce GFR)
- Mesangial cells contract
What happens when the pressure is rising during systole + decreasing during diastole?
Frequency of afferent impulses increases
Where is the cardiovascular centre located?
In the medulla of the brainstem
What are the 2 components of the cardiovascular centre and what do they do?
- Cardiostimulatory: make the heart beat faster and stronger
- Cardioinhibitory: slow the heart down
What is the vasomotor center?
Cluster of sympathetic neurons in medulla (oversee changes in blood vessel diameter)
What is primary hypertension?
95% of all hypertension
-Combined systolic + diastolic
What is secondary hypertension?
Usually from kidney disease, adrenocrotical disorders, primary aldosteronism, pheochromocytoma, renal artery stenosis & coarctation of the aorta
What are some risk factors for primary hypertension?
-Obesity, genetics, aging, hyperlipidemia, sleep apnoea, smoking, increased blood viscosity
What causes secondary hypertension?
Systemic disease that raises peripheral resistance
What is malignant hypertension?
Intense spam of arteries e.g cerebral arteries, retinal vessels (swelling of optic nerve)
-Sudden development of extremely high blood pressure
What are modifiable risk factors for hypertension
- Diet
- Obesity
- Smoking
- Oral contraceptives
What are some treatments for hypertension?
Diuretics, ACE inhibitors, Ca channel blockers, beta blockers
What is atherosclerosis?
Progressive disease characterised by thickening and hardening of arteries caused by formation of fibrofatty plaques
