Lecture 11 - Blood flow control & Kidneys Flashcards
Describe the mechanism of acute control of blood flow
Vasoconstriction/dilation by means of changes to SNS tone
Describe the mechanism behind long-term blood flow control
Tissue remodeling (any others???)
Describe the theory of vasodilation in acute blood flow control.
Increased metabolic activity -> decreased [oxygen] -> formation of vasodilators
Describe the theory of oxygen/nutrient lack in acute blood flow control.
Decr. [oxygen] causes a decrease in SNS tone -> blood vessel relaxation -> vasodilation
Cyclical opening and closing of precapillary sphincters is known as ______.
vasomotion
Why can pre-capillary sphincters remain contracted for only short times with decreased [oxygen]?
Long term contraction requires oxygen (oxydative phosphorylation to reconstitute ATP)
Describe reactive hyperemia.
Due to blocked blood flow, tissues “react” when the blockage is removed; this increased blood flow 4-7x more than normal
Describe active hyperemia
Increased metabolic activity in a tissue causes an increase in blood flow. This is to increased nutrient transport/removal of waste.
Blood flow autoregulation show and increased blood flow and (an increase/a decrease) in BP.
decrease
In autoregulation, blood pressure (is/is not) returned to normal.
Is not; autoregulation of flow has NOTHING to do with control of blood pressure
What are the two theories of autoregulation of blood flow?
Metabolic:
increased metabolism -> increased blood flow -> too much O2/nutrients -> “wash out” of vasodilators
Myogenic:
Increased blood flow -> blood vessel dilation -> reactive vasoconstriction
Myogenic autoregulation can occur without the presence of ______.
Vasosconstrictors (appears to be mediated by smooth m.)
Monitors [NaCl] in the juxtaglomerular apparatus.
macula densa (part of DCT)
Secretes renin
Juxtaglomerular cells
Healthy endothelium secretes _____, which helps with maintaining vessel tone.
Nitric oxide (NO)
Nitric oxide assists in the reaction of __ to ___.
cGTP to cGMP
cGMP is important in the activation of _______, which promote vasodilation.
protein kinases
cGTP is found in ______
vascular smooth muscle cells
Damaged cells (either through HTN or trauma) secrete _____, which promotes vasoconstriction.
endothelin
Damage to endothelium may cause hypertension by what mechanism?
Lack of NO production. This causes decreased [endothelin] -> [Nitric oxide] -> vasoconstriction; (+) feed back; essentially, the lack of nitric oxide from damaged endothelium produces HTN
Circulation control is also mediated by humoral factors. What vasoconstriction mediators are present?
- NE
- Epi
- ANG II
- Vasopressin
Released from SNS neurons, is a vasoconstrictor
norepinephrine
Released from the adrenal glands, is a vasoconstrictor
epinephrine
This hormone, also known as “ADH,” acts on the vessels to increase peripheral resistance
vasopressin
Acts as a vasoconstrictor, controls body fluid volume; also prevents water loss
vasopressin (“vaso”-vessel; “-pressin” - increases pressure); AKA “ADH”
Acts as a vasodilator by increasing capillary permeability
bradykinin
Acts as a powerful vasodilator; is released from Mast cells/basophils
Histamine
The SNS innervates all vessels except ______.
capillaries
SNS innervation arises from _____ to _____.
T1-L2/L3
Cervical sympathetic innervation arises from _____.
the level of T1
What are two “phases” of local blood flow control?
- acute
- long-term
The vasomotor segment of the brainstem is located in the (medulla/pons/hypothalamus).
Hypothalamus
This region of the vasomotor center continually fires and acts to maintain normal vasomotor tone.
vasoconstrictor
This region acts as an inhibitor to the medullary vasoconstrictor area.
vasodilator area
The sensory area of the vasomotor region is located in the _____.
posterolateral portion of the medulla
The sensory area of the vasomotor receives sensory input from what two Cranial Nerves?
Glossopharyngeal (CN IX) and vagus (CN X)
BP less than ____ stimulates the carotid baro-R
60 mmHg
BP less than ____ stimulates the aortic baro-R
30 mmHg
What is the f(x) of the adrenal medulla?
Secretion of epinephrine and norepinephrine
Neural control of arterial pressure occurs through severl simultaneous changes to cardiovascular f(x). What are they?
- constriction of systemic arteries
- constriction of veins
- increased heart rate
Which of the following is NOT constricted by epinephrine/norepinephrine?
a) capillaries
b) veins
c) arterioles
d) arteries
a) capillaries
What two receptors respond primarily to low blood pressure?
carotid and aortic sinuses
These are _____
Herring’s nerves (carotid baro-R)
Outline the formation of atheromas on the walls of arteries.
1) Injury to endothelium causes macrophage recruitment. These macrophages ingest LDL, forming “foam cells.”
2) Foam cells release chemotactic factors, which cause growth of tunica intima
3) CAMs recruit other cells (monocytes/Tcells), forming a deposit
4) Atheroma cap- smooth m., foam cells; atheroma “body”-cell debris, calcium, cholesterol, etc.
Short connection between CN IX and the carotid baroreceptors.
Hering’s N.
Connection between brainstem and the aortic baroreceptors
CN X (vagus nerve)
BP = CO x _____
A. Total Peripheral Resistance
B. Flow
C. Vessel Diameter
A. TPR
Which of the following is NOT a cause of primary hypertension? A. Increased SNS stimulation B. Inadequate salt/water loss C. Decreased cardiac output D. Increase in Renin-Angiogensin system
C. decreased cardiac output
A patient with increased blood pressure is noted to have an increased urinary output. This is known as:
A. Pressure Natriuresis
B. Pressure Diuresis
C. Pressure controlled Renin-Angiotensin Activation
B. Pressure diuresis
Causes of HTN can be “comparmentalized” into three main causes. What are they?
Endocrine, cardiovascular, and neurologic causes
Which of the following is not a cardiovascular cause of hypertension? A. Increased cardiac output B. Coarcation of the Aorta C. psychosis D. Increased blood volume
C. psychosis
Which of the following is not a neurologic cause of HTN. A. sleep apnea B. stress C. increased intracranial pressure D. Cushing's syndrome
D. Cushing’s syndrome
Prostayclin is a potent vaso____.
A. -dilator
B. -constrictor
A. -dilator
The major characteristic of of atherosclerosis is ____.
the projection of a lesion into the lumen of the blood vessel
This is a major marker for inflammation, and is linked to atherosclerotic plaque formation. A. C-reactive protein B. Foam cells C. Cholesterol D. Cysteine
A. C-reactive protein (CRP)
This is an inborn error of metabolism and is associated with early onset cardiovascular disease. A. presence of C-reactive protein B. presence of Foam cells C. Hyperhomocystenemia D. Familial Hypercholesterolemia
C. Hyperhomocystenemia
This is associated with insulin resistance, and is characterized by obesity, fasting hyperglycemia, increased triglycerides, and HTN A. Hyperhomocysteinemia B. Juvenile Onset Diabetes C. Metabolic Syndrome D. Insulin Resistance Syndrome
C. Metabolic syndrome
Short term control of arterial pressure is accomplished by:
A. SNS control
B. Nervous/Hormonal/Renal control
A. SNS control
Long term arterial pressure is controlled by:
A. SNS control
B. Renal/Neural/Hormonal control
B. Renal/Neural/Hormonal control
This occurs when one’s mean arterial pressure is greater than the upper range of the accepted normal pressure.
Chronic hypertension
Destruction of functional kidney tissue is responsible for increased levels of blood ___.
Urea
Renin is secreted by the \_\_\_\_ and acts produce \_\_\_\_\_. A. Kidney; angiotensin I B. Liver; angiotensinogen C. Kidney; Angiotensin II D. Liver; Angiotensin I
A. Kidney; angiotensin I
Angiotensin I is converted to angiotensin II in the lungs by \_\_\_\_\_. A. Renin B. Angiotensin converting enzyme C. Aldosterone D. Angiotensiogenase
B. Angiotensin converting enzyme
In addition to promoting renal retention of salt/water, angiotensin II also produces ______.
Vasoconstriction
Atrial stretch produces atrial natriuretic peptide which results in vaso____.
A. -constriction
B. -dilation
B. -dilation
One-Kidney Goldblatt Hypertension results in a decrease in distal renal arterial pressure. Why?
The renal artery is constricted in this procedure. As a result, there is decreased blood flow (distal renal pressure) from the clamp. However, systemic arterial pressure INCREASES due to an increase in resistance, during which the pressure is increased to overcome it.
In addition to [ion] control, what are the other important functions of the kidney?
- acid-base control
- EPO secretion
- 1,25-dihhdroxy D3 production
- Gluconeogenesis
