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63 Cards in this Set

  • Front
  • Back
In contrast to local regulation how can blood flow be regulated in a more global way?
By humoral mechanisms - substances secreted or absorbed into body fluids.
3 categories of humoral agent mechanisms:
1. Endocrine
2. Autocrine
3. Paracrine
What is the general mechanism of humoral bloodflow regulators?
1. Ligand carried in bloodstream
2. Ligand diffuses into ISF thru endothelial cells
3. Ligand binds receptor on vascular smooth muscle
4. Modifies G protein inside smooth muscle cell
5. Gprotein alters enzyme cascade to produce effect
What happens when Gprotein activates PLC?
PLC acts to produce IP3 + DAG
What does DAG do?
Activates PKC - protein kinase C which stimulates smooth muscle contraction.
What does IP3 do?
Stimulates release of Calcium for smooth muscle contraction.
What can Gprotein activate other than PLC?
What is the action of PLA2?
What is Norepinephrine's effect on blood flow?
It is a vasoconstrictor
How does NE cause vasoconstriction?
It binds a GPCR to stim Gq, which activates PLC to split DAG + IP3 to release calcium stores from SR and activate PKC
What does calcium release from the SR accomplish?
Activation of MLCK - constriction of blood vessels
What inhibits MLCK?
What does Nitric Oxide do?
Vasodilates - inhibits constriction by inhibiting PMCA from allowing calcium influx.
What is Endothelin 1?
A hormone that affects vessels
What are the 2 receptors for ET-1 and what happens when either is bound?
ETA receptor Constrict
ETB receptor Dilate
How is ET-1 secretion regulated?
By transcription of its genes - there are many stimulators and inhibitors.
What types of molecules stimulate ET1 secretion?
What types of molecules inhibit ET-1 secretion?
What is the main effect of endothelin?
Where is norepinephrine made?
In noradrenergic cells
Where is epinephrine made?
In adrenal medullary cells
What are norepi/epi made from?
Phe -> Tyrosine -> Dopa -> Dopamine -> NE -> Epi
4 types of Adrenergic receptors:
How do you remember what binds what?
Alpha binds Norepi
Beta binds Epi
Where are Alpha 1 adrenergic receptors?
In vascular smooth muscle
What happens when NE binds a1 receptors?
Where are A2 receptors located?
In Sympathetic nerve varicosities
What happens when NE binds A2 receptors?
These are autoreceptors - it inhibits NE release
Where are B1 receptors located?
Heart SA Node
Atrial/ventricular muscle
AV node/Purkinje fibers
What happens when Epi binds B1 receptors?
Increases HR, Contraction, Conduction, and Velocity
Where are B2 receptors?
Vascular smooth muscle
What happens when Epi binds B2 receptors?
Relaxation - opposite of NE on alpha1
What are the 3 important enzymes of the RAS?
-Angiotensin Converting enzyme
Where is Renin produced?
What does Renin do?
In the kidney - it converts Antiotensinogen into Angiotensin I
What does Angiotensin I do?
What does Angiotensin converting enzyme do?
Converts Angiotensin I into Angiotensin II - the main active protein here.
How many amino acids are in AT2?
What is ACE?
Another name for angiotensin II converting enzyme.
What does AT2 bind?
At1 receptors or AT2 receptors
What happens when Angiotensin II binds AT1 receptors? AT2?
AT1: vasoconstriction/angiogen.

AT2: vasodilates/vessel rarefact
What is the major function of Angiotensin II?
A negative feedback controller of acute hemorrhage changes in arterial pressure.
How does AT2 respond to an acute hemorrhage?
As arterial pressure decreases from 100 to 40, the Kidney releases Renin; AT2 is produced to raise BP up to 80.
What is the gain in the previous example?
Gain = correction/error remain
Gain = -2.0 (40/20)
What are ACE inhibitors prescribed for?
BP medicine
What is an annoying side effect of ACE inhibitors and why?
Coughing - because it prevents Bradykinin break down and Bradykinin induces coughing.
What is Vasopressin?
Where is it made/produced?
ADH - a potent vasocontrictor.
Made in hypothalamus, released from posterior pituitary.
What is the main role of Vasopressin?
Renal function controller - antidiuretic so it makes you retain salt - sodium.
What acts oppositely to ADH?
ANP - atrial natiuretic peptide
How do you know ANP makes you excrete sodium?
Because its name tells you thats what it does.
How does ANP affect blood pressure?
It lowers it.
How do ADH and RAS affect BP?
They raise it. Thats why you give ACE inhibitors.
What is ANP approved to use to treat?
Congestive heart failure
3 Actions of ANP:
-Reduces aldosterone secretion
What ions/molecules cause constriction of blood vessels?
What ions/molecules cause dilation of blood vessels?
Where is Angiotensin II made?
In the brain and heart
What does serotonin do?
5 Humoral Vasoconstrictors:
Angiotensin II
5 Humoral Vasodilators
1 Local vasoconstrictor
Myogenic response
7 Local vasodilators:
-PO2 reduction
-Increased K, CO2, H+
-Nitric oxide
Neural vasoconstrictor
Sympathetic nerves
Neural vasodilator
Neurons releasing NO