Topic 8 - CVD 1

Question 1

Hypertension

Answer 1

Constant elevation of systemic arterial BP, resulting from sustained ↑ in TPR, ↑blood volume or both

Risk factors
- age, race, stress, obesity, Na intake, excessive alcohol, low vit d, low k diet, chronic conditions

Consequences - chronic hypertension

• stiffness of arteries
• left <3 failure
• stroke
• kidney failure
• blindness

Question 2

Types of Hypertension

Answer 2

Primary / essential / idiopathic
- most common
- combination of D+S hypertension
Secondary
- caused by underlying disease, e.g. renal
Isolated S/D
- only systolic/diastolic affected

Question 3

ECG wave

Answer 3

P wave = atrial depol (atrial cont.)
- contributes to generation of AP
- movement of ions into cells and cell becoming +
QRS complex = ventricular depol (V systole)
- atrial depol also occurs here but is masked
T wave = ventricular repol
- membrane potential becomes -ve
Q-T interval = ventricular systole

Question 4

Preload / EDV

Answer 4

workload imposed upon ventricle prior to contraction/systole
volume and pressure generated in the ventricle at the end of diastole
Causes lengthening of myocardial fibres

Question 5

Frank-Starling mechanism

Answer 5

“within physiological limits, the force of contraction of the heart is directly proportional to initial length of muscle fibres”

Ability of heart to changes its force of contraction and therefore SV in response to changes in venous return

Question 6

Afterload

Answer 6

The force required to eject blood from the heart
Impedance to ejection of blood varies depending on
- systemic vascular resistance
- ventricular wall tension

Question 7

1. Arterial Pressure

Answer 7

Arterial BP = CO x TPR
Measure AP during S or D
S = pressure during ventricular contraction
D = pressure during ventricular filling
Important AP is regulated to maintain tissue perfusion

Question 8

2. Effect of Cardiac Output

Answer 8

Q changes due to alterations in SV and/or HR
If Q ↑ = arterial blood volume ↑ = AP ↑
if Q ↓ = arterial BP ↓

Question 9

3. Effects of TPR

Answer 9

Resistance provided by the vascular system
Determined by changes in diameter of arterioles
VasoC = ↑ AP VasoD = ↓ AP
Constriction and dilation regulated by neural control
- baroR
- chemoR
- SNS innervates arteriole smooth muscle

Question 10

4. Effects of Hormones

Answer 10

1. RAAS
   renin secreted by kidneys in response to low Na
   release of renin stimulated by ↓ in BP
   renin acts on angiotensinogen to form angiotensin 1
   Ag1 forms Ag2 by ACE = powerful vasocon
   Release of aldosterone from kidneys
2. ADH
   causes reabsorption of water by kidneys
   secreted by PP into blood
   potent vasocon (↑ TPR)
   released in response to ↓ in plasma volume detected by baroreceptors
   ↑ blood plasma volume by ↑ permeability of kidneys at DCT so water is retained making urine concentrated