Blood Vessels Flashcards
(42 cards)
What is the locations of Baroreceptors
Carotid sinuses
Aortic arch
Walls of large arteries of the neck and thorax
What is the function of Baroreceptors?
Inhibits vasomotor and cardioacceleratory centers
-causing arteriolar dilation and venodilation
Baroreceptors are decreased in blood pressure due to…
Arteriolar vasodilation
Venodilation
Decreased cardiac output
What is the function of Chemoreceptors?
Detect increase in CO2, or drop in pH or O2
Causes increase blood pressure
How do chemoreceptors causes increase in blood pressure?
By signaling cardioacceleratory center (which increase CO)
By signaling vasomotor center (which increase vasoconstriction)
What are influences of Higher Brain Centers?
Reflexes in the medulla
Hypothalamus and cerebral cortex can modify arterial pressure via relays to the medulla
Hypothalamus increase blood pressure during stress
Hypothalamus mediates redistribution of blood flow during exercise and changes in body temperature
Hormonal Controls
Short term regulation…via changes in peripheral resistance
Long term regulation…via changes in blood volume
What is the function of neural controls of peripheral resistance?
- Maintain MAP by altering blood vessel diameter
- Alter blood distribution to organs in response to specific demands
- Operate via reflex arcs*
What hormonal controls increase blood pressure?
Epinephrine and norepinephrine from adrenal gland–increases CO and vasoconstriction
Angiotensin 2 stimulate vasoconstriction
High ADH levels causes vasoconstriction
What hormonal controls decreases blood pressure?
Atrial natriuretic peptide causes decreased blood volume by antagonizing aldosterone
What two ways does the kidneys regulates arterial blood pressure?
- By direct renal mechanism
2. By indirect renal (renin-angiotensin-aldosterone) mechanism
What are the functions of Direct Renal Mechanism?
Alters blood volume independently of hormones
- increased blood pressure or blood volume causes elimination of more urine (thus reducing blood pressure)
- decreased blood pressure or blood volume causes kidneys to conserve water, and blood pressure rises
Indirect Mechanism
Explain the renin-angiotensin-aldosterone mechanism….
Decreased arterial blood pressure - releases renin
Renin catalyzes conversion of angiotensingen from liver to angiotensin 1
Angiotensin converting enzyme (from the lungs) converts angiotensin 1 to angiotensin 2
What is the function of Angiotensin 2?
Increases blood volume
- stimulates aldosterone secretion - causes ADH release - triggers hypothalamus thirst center
Causes vasoconstriction to increase blood pressure
Define Vital Signs
Pulse and blood pressure, alone with respiratory rate and body temperature
Define Pulse
Pressure wave caused by expansion and recoil of arteries
How is Systemic Arterial BP is measured?
Measured indirectly by auscultatory method using a sphygmomanometer
Pressure increased in cuff until it exceeds systolic pressure in brachial artery
Pressure released slowly and examiner listens for sounds of Korotkoff with a stethoscope
How to measure Systolic Pressure?
Normally less than 120 mmHg
Is pressure when sounds first occur as blood starts to spurt through artery
How is Diastolic Pressure measured?
Normally less than 80 mmHg
Is pressure when sounds disappear because artery no longer constricted (blood flows freely)
Hypertension of Blood Pressure
Sustained elevated arterial pressure of 140/90
Prehypertension of Blood Pressure
Happens if valves elevated but not in hypertension range
May be transient adaptation during fever, physical exertion, and emotional upset
Persistent in obese people
What are the major causes of prolonged hypertension?
Heart Failure, Vascular Disease, Renal Failure, and Stroke
Heart must work harder
Myocardium enlargers, weakens, and becomes flabby
Also accelerate atherosclerosis
Primary Hypertension
Is 90% of hypertension condition
Has no underlying causes
Has no cure (can be controlled)
Risk Factor of Primary Hypertension
Heredity Diet Obesity Age Diabetes Mellitus Stress Smoking
