Regulation of the vasculature by the endothelium And controlling of ABP - 28

Question 1

Important endothelial vasodilators

Answer 1

nitric oxide, prostacyclin (PGI2), and
endothelium-derived hyperpolarizing factor
(EDHF).

Question 2

The major endothelial vasoconstrictors a

Answer 2

ndothelin-1, thromboxane A2 (TXA2) and

prostaglandin H2.

Question 3

Arterial blood pressure control mechanisms:

Answer 3

• It divided into three mechanisms:
• 1-Rapidly Acting Pressure Control.
• 2-Intermediate Pressure Control Mechanisms
• 3- long term Pressure Control Mechanisms

Question 4

Rapidly Acting Pressure Control Mechanisms

Answer 4

(1) The Baroreceptor feedback
2) Arterial chemoreceptor mechanism: occurs only
when ABP below 80 mmHg.
3- The CNS ischemic response: (less than 60)
(4) Abdominal compression reflex

Question 5

The CNS ischemic response

Answer 5

(less than 60)
• ABP decreases markedly, cerebral ischemia occurs
which produces powerful VC and elevation of ABP
to improve blood flow to the brain.
• So that, it acts as emergency pressure control
system to prevent further decrease ABP and blood
flow to the brain close to lethal level.

Question 6

Abdominal compression reflex.

Answer 6

When ABP decreases, signals send to skeletal muscle
of abdomen. Causes compression of venous reservoirs
of abdomen to push blood out of abdomen to heart.

Question 7

Intermediate Pressure Control Mechanisms

Answer 7

• within 30 minutes to several hr
  1-The renin-angiotensin vasoconstrictor system
  2-The stress-relaxation mechanism:
  3-The capillary fluid shift mechanism
  4- Atrial Reflexes: (The “Volume reflex.)

Question 8

2-The stress-relaxation mechanism

Answer 8

The gradual relaxation
of vascular smooth when
gradual stretched of vessels for
period of time is called
stress relaxation or
delayed vascular compliance .

Question 9

3-The capillary fluid shift mechanism

Answer 9

When ABP decreases, fluid is absorbed through the
capillary from the tissues into the circulation, thus
increasing both the blood volume and ABP.

Question 10

4- Atrial Reflexes: (The “Volume reflex.)

Answer 10

Rt. Atrium
receptor (volume receptor)----->
- Kidney: VD of Afferent,
Increase
excretion
of salt & water
- Hypothalamus
Decrease ADH
- Secret ANP to
excrete Na and H2o

Question 11

• C- Long-Term Mechanisms:

Answer 11

1-Excessive accumulative salt intake leads to
increase blood volume as well as increase ABP.
-The kidney begins to response to high ABP
causing pressure diuresis and natriuresis

2-Also, a decrease in arterial pressure leads stimulates
renin secretion from kidney that forming
angiotensin II causing the kidneys to retain both salts
and water.

Question 12

Pathophysiology of ABP

Answer 12

-Arterial hypertension

Low arterial pressure (Hypotension)

Question 13

1-Arterial hypertension

Answer 13

Definition: It’s a chronic state of elevated arterial blood
pressure includes an abnormal elevation in diastolic
and/or systolic pressure.
• This disease is sometimes called the “silent killer.” This
disease is usually asymptomatic until the damaging
effects of hypertension are observed.

Question 14

Low arterial pressure (Hypotension

Answer 14

• Blood pressure that is too low below 90/60

mmHg is known as hypotension