blood pressure and blood flow

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chap 20 A&P exam 2

various methods of BP Regulation include which of the following?

a)Neural control
b)Hormonal control
c)Autoregulation
d) all of the above

d

Nervous system regulates blood pressure using negative feedback loops that occur as 2 types of reflexes. what are they called?

Baroreceptor reflex
Chemoreceptor reflex

what are baroreceptors?

Pressure sensitive sensory receptors that cause changes in the rate of impulses sent to the brain

true or false, pressure is indirectly proportional to impulse rate.

false

where can we find barorecptors?

aorta, carotid arteries, and other large arteries in the neck and chest

the 2 most important baroreceptor reflexes are?

Carotid sinus reflex- From baroreceptors found in the wall of the carotid sinus, Helps regulate blood pressure in the brain
Aortic reflex- From baroreceptors found in the wall of the ascending aorta and aortic arch, Regulates systemic blood pressure

Chemoreceptors are?

1.Sensory receptors that monitor chemical changes in the blood
2.Located close to the baroreceptors of the carotid sinus and aortic bodies
3.Detect changes in blood level increase in CO2, drop in pH, or drop in O2~ Hypoxia = low O2 availability Acidosis = increase in H+ concentration above normal Hypercapnia = excess CO2
4.Cause increased blood pressure by stimulating sypathetic stimulation
5.Signaling cardioacceleratory center  increase CO
Signaling vasomotor center  increase vasoconstriction
6.Also send signals to the respiratory center for adjustment of breathing rate

what are the 4 hormones that control the Regulation of blood pressure and flow?

1.Renin-angiotensin-aldosterone (RAA) system- released by kidneys when blood volume falls or blood flow decreases.
It causes the conversion of precursors into the active hormone angiotensin II which raises BP by vasoconstriction and by stimulating secretion of aldosterone from the adrenal glands.

2.Epinephrine and norepinephrine- Released from the adrenal medulla as an endocrine autoregulatory response to sympathetic stimulation.They increase cardiac output by increasing rate and force of heart contractions.

3.Antidiuretic hormone- released from the posterior pituitary gland in response to dehydration or decreased blood volume.

4.Atrial Naturetic Peptide- a natural diuretic polypeptide hormone released by cells of the cardiac atria. ANP participates in autoregulation by:Lowering blood pressure (it causes a direct vasodilation) Reducing blood volume (by promoting loss of salt and water as urine)

The ability of a tissue to automatically adjust its blood flow to match its metabolic demand is known as?

Autoregulation

what are the 2 general types of stimuli that cause autoregulatory changes in blood flow?

Metabolic controls
Myogenic controls

how is autoregulation controlled?

Controlled intrinsically by modifying diameter of local arterioles feeding capillaries

responses to Declining tissue O2, Substances from metabolically active tissues (H+, K+, adenosine, and prostaglandins) and inflammatory chemicals are due to _______.

Vasodilation of arterioles and relaxation of precapillary sphincters

name some effects of metabolic controls.

Relaxation of vascular smooth muscle
Release of Nitric Oxide (powerful vasodilator) by endothelial cells

_______ _______ keep tissue perfusion constant despite most fluctuations in systemic pressure.

Myogenic responses

which type of stretch promotes increased tone and vasoconstriction in smooth muscle?

Passive stretch

which type of stretch promotes vasodilation and increases blood flow to the tissue?

Reduced stretch

In an autoregulatory response, what is the important differences that exist between the pulmonary and systemic circulations?

Systemic blood vessel walls dilate in response to hypoxia (low O2) or acidosis to increase blood flow.

The walls of the pulmonary blood vessels constrict to a hypoxic or acidosis stimulus to ensure that most blood flow is diverted to better ventilated areas of the lung.

what is Angiogenesis?

Occurs when short term autoregulation cannot meet tissue nutrient requirements. Either the number of vessels to a region increases or existing vessels enlarge.

when does angiogenisis commonly occur?

Common in heart when coronary vessel occluded, or throughout body in people in high-altitude areas

what is the most common disorder that affects the CV system and is a major cause of atherosclerotic vascular disease heart failure, kidney disease and stroke?

hypertension

hypertension is defined as ______.

an elevated systolic blood pressure (SBP), an elevated diastolic blood pressure (DBP), or both.

what is Hypotension?

defined as any blood pressure too low to allow sufficient blood flow (hypo-perfusion) to meet the body's metabolic demands (to maintain homeostasis).

shock occurs when?

Failure of the cardiovascular system to deliver enough oxygen and nutrients to meet cellular metabolic demands If shock persists, organs can be come damaged or die

The 4 basic types of shock are?

Hypovolemic shock- due to decreased blood volume

Cardiogenic shock- due to poor heart function

Obstructive shock- due to obstruction of blood flow

Vascular shock- due to excess vasodilation - as seen in cases of a massive allergy (anaphylaxis) or sepsis. In the U.S., septic shock causes >100,000 deaths/yr. and is the most common cause of death in hospital critical care units.

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