Lecture 31

Question 1

where are arterioles located

Answer 1

Located within individual organs (including muscle)

Question 2

“They are the greatest contributors to Total peripheral resistance by increasing or decreasing the size of the lumen; important regulators of MAP”

Answer 2

arterioles

Question 3

what “Determine blood flow to individual organs”

Answer 3

arterioles

Question 4

what are the 2 major cell types that arterioles are comprised of:

Answer 4

Endothelial cells
Vascular smooth muscle

Question 5

Why does pressure DROP so much at the arterioles?

Answer 5

dissipation of blood flow through all the different organs

high pressure to low pressure (pressure gradient)

This drop in pressure is necessary to ensure that the capillaries downstream, which have even smaller diameters, do not rupture under the pressure of the blood flow.

Question 6

what are the Principal Determinants of Flow

Answer 6

1.Effect of pressure gradient:
The pressure gradient along the length of the tube
determines blood flow

2.Effect of radius (size of blood vessel):
Controls resistance
Resistance is also increased by tube length and
viscosity of blood
Lower resistance (greater radius) = greater flow

Question 7

Blood flow to each organ is not the same. true or false

Answer 7

true

Question 8

How does your body decide where to send the blood?

Answer 8

We have to be able to control the size of the blood vessels to alter resistance when we want to control which part of the body gets more or less blood

Question 9

Functions of Endothelial Cells

Answer 9

Line heart and blood vessels; prevent blood cell and platelet adherence (thrombosis)
Control the exchange of fluid and nutrients in capillaries
Secrete vasodilator (nitric oxide) and vasoconstrictor (endothelin) substances
Mediate new capillary growth (angiogenesis)
Regular inflammatory responses

Question 10

Functions of Smooth Muscle Cells

Answer 10

Maintain shape of blood vessel (structural support)
Regulate local blood flow via changing vessel diameter (vasoconstriction or vasodilation)

Question 11

Signals that increase actin-myosin x-bridges cause…

Answer 11

vasoconstriction

Question 12

Signals that decrease actin-myosin x-bridges cause…

Answer 12

vasodilation

Question 13

Nitric Oxide (NO) is produced primarily by

Answer 13

endothelial cells

Question 14

In each endothelial cell, there is an enzyme called

Answer 14

nitric oxide synthase

Question 15

nitric oxide synthase enzyme turns l-arginine to…

Answer 15

nitric oxide

Question 16

Nitric oxide is a small molecule that diffuses quickly into

Answer 16

smooth muscle

Question 17

what does nitric oxide do in smooth muscle

Answer 17

In the smooth muscle, nitric oxide activates another enzyme called guanylate cyclase

Question 18

once activated by nitric oxide what does Guanylate cyclase do in smooth muscle

Answer 18

Guanylate cyclase will create cGMP, causing relaxation of the smooth muscle cells

Question 19

what does the relaxation of the smooth muscle cells via Guanylate cyclase do

Answer 19

This relaxation causes vasodilation; increases radius; decreases resistance; increases flow

Question 20

Another enzyme, ______________________, creates ________________ from ____________________ It then cycles back to ______________

Answer 20

phosphodiesterase (PDE)
GMP (guanosine monophosphate)
cGMP
GTP

Question 21

Why don’t we always want cGMP in our system

Answer 21

We don’t always want cGMP in our system because we don’t always want to be vasodilated

Question 22

how do Dietary Nitrate Supplements work

Answer 22

When consumed in the diet, nitrate is converted in the body to nitric oxide (NO), a molecule that plays a key role in regulating blood flow and oxygen delivery to tissues.

Increased nitric oxide production: Dietary nitrate supplements increase the production of nitric oxide in the body, which can cause blood vessels to dilate, or widen, resulting in increased blood flow to muscles and other tissues.

Improved oxygen delivery: By improving blood flow, nitric oxide helps to deliver more oxygen to working muscles, which can improve exercise performance and delay the onset of fatigue.

Reduced oxygen consumption: Nitric oxide has been shown to reduce the amount of oxygen that muscles consume during exercise, which can improve endurance and delay the onset of fatigue.

Improved muscle efficiency: Nitric oxide can improve the efficiency of muscle contractions, allowing muscles to generate more force with less oxygen consumption.