Chapter 10 Blood Vessels

Question 1

How does the layout of blood vessels help ensure that each organ receives freshly oxygenated blood?

Answer 1

they have a system of many parallel blood vessels

Question 2

What does it mean to recondition blood?

Answer 2

removing waste from blood and/or adding nutrients

Question 3

What is the sequence of blood vessels that blood flows through?

Answer 3

arteries, arterioles, capillaries, venules, veins

Question 4

In which vessel are gases exchanged with body cells or with the lungs?

Answer 4

Capillaries

Question 5

Blood flow through vessels is ________ proportional to the pressure gradient.

Answer 5

directly

Question 6

Blood flow through vessels is ________ proportional to the vascular resistance.

Answer 6

inversely

Question 7

Could you use Poiseuille’s law to calculate flow rate, or changes in flow rate?

Answer 7

brings all the variables together to describe flow rate

Question 8

What are the two main functions of arteries? What features of the arteries allow them to carry out these functions?

Answer 8

1. Provide rapid transit of blood to organs
2. Acts as a pressure reservoir when the ventricle is relaxing

Question 9

How do arterial walls change during systole and diastole? How about arterial pressure?

Answer 9

-Walls expand
-no pressure generated by heart, but pressure maintained by relaxation of arterial walls

Question 10

What causes the pulse that we can feel?

Answer 10

Pressure surge expands arterial walls

Question 11

What properties of arteries give them little vascular resistance?

Answer 11

They have a wide diameter

Question 12

Could you explain how blood pressure can be measured with a sphygmomanometer? Is this measurement direct or indirect? What causes the sound?

Answer 12

A blood pressure cuff with an attached pressure gauge indirectly measures blood pressure. Momentarily occluded after causes turbulent blood flow causing sound.

Question 13

Where are arterioles found?

Answer 13

when an artery reaches an organ and branches into arterioles

Question 14

How do arterioles differ from arteries in size and resistance?

Answer 14

Arterioles have much smaller diameter than arteries -> greater vascular resistance

Question 15

What is vascular tone?

Answer 15

When arteries are partially constricted at rest

Question 16

How does increased metabolism in a tissue affect arteriole diameter? By what mechanism? Is this local or extrinsic control of arteriolar diameter?

Answer 16

Increased metabolic activity of tissue causes the following changes in the local vicinity:
-decreased O2
-increased CO2
-increased acid (from CO2 or lactate)
-increased extracellular K+
-increased osmolarity
-adenosine released

Question 17

What is active hyperemia?

Answer 17

Increased blood flow to a tissue due to increased tissue activity

Question 18

How does sympathetic nervous activity lead to changes in arteriolar diameter? Is this local or extrinsic control of arteriolar diameter?

Answer 18

Sympathetic nervous actively releases NE, which acts on smooth muscle to cause bodyside arteriolar vasoconstriction
- Extrinsic

Question 19

What affect does arteriolar diameter have on arterial blood pressure?

Answer 19

As vessel diameter decreases, the resistance increases and blood flow decreases.

Question 20

What does stretch of arterioles from a sharp change in blood pressure trigger? How?

Answer 20

Stretch from increased blood pressure opens channels, increasing depolarization leading to vasoconstriction.

Question 21

What effect does histamine have on arterioles?

Answer 21

It can act as paracrine in vicinity of affected tissue, causes vasodilation

Question 22

What is the main function of capillaries?

Answer 22

They’re the main site of exchange of O2, CO2, waste, nutrients, etc.

Question 23

How do gases pass thru capillaries? How about ions and small molecules like glucose? How about hydrophilic proteins? Do plasma proteins pass thru the capillaries?

Answer 23

• Lipid-soluble substances pass through the endothelial cell
  -Small water-soluble substances pass through the pores
• Exchangeable proteins are moved across by vascular transport
  -Plasma proteins generally cannot cross the capillary wall

Question 24

Does blood flow faster or slower thru capillaries? Why?

Answer 24

Blood flows at slower speed through capillaries so there is more time for diffusion

Question 25

What is the direction of the diffusion gradient between capillaries and body cells for O2, CO2, and glucose?

Answer 25

Glucose, O2, CO2, and waste flow down natural concentrations gradients across plasma, interstitial fluid, and body cells

Question 26

What is a metarteriole?

Answer 26

thoroughfare vessel that directly links arterioles to venules

Question 27

What are precapillary sphincters and how are they involved in vasoconstriction and vasodilation?

Answer 27

-(smooth muscle) surround initial segment of capillary leaving arteriole or metarteriole
-vasoconstriction of arterioles co-occurs with constriction of precapillary sphincters
-vasodilation of arterioles co-occur with relaxation of precapillary sphincters

Question 28

What is bulk flow? What different types of pressures help determine bulk flow?

Answer 28

-Protein-free plasma flowing out of (ultrafiltration) and into (reabsorption) the pores of capillaries
-Ultrafiltration- tends to occur closer to the arterioles
-Reabsorption- tends to occur closer to the venules

Question 29

Is capillary blood pressure constant all throughout the capillaries? How about plasma- colloid osmotic pressure? How does this cause ultrafiltration at one end and reabsorption at the other?

Answer 29

-Capillary bp decreases from arterioles to venules due to vascular resistance
-Plasma-colloid op- due to plasma proteins stuck inside capillary

Question 30

Is there normally a net entry into or net exit out of capillaries of plasma? Where does the excess go?

Answer 30

Net outward pressure of 11mm Hg=Ultrafiltration
Net inward pressure of 9mm Hg= Reabsorption pressure
There is a net act of fluid that is always trickling out and doesn’t return

Question 31

How is lymph propelled forward?

Answer 31

1. Smooth muscle that constricts automatically when vessel is distended
2. Squeezing of lymph vessels between contracting skeletal muscles

Question 32

Where do lymph vessels dump into in the circulatory system?

Answer 32

Into the vena cava

Question 33

How are veins similar to and different from arteries?

Answer 33

Like arteries, veins have a large diameter
Unlike arteries, veins have much less elastin in vessel wall

Question 34

What is venous return? Could you identify factors that influence venous return from a list?

Answer 34

volume of blood per unit of time entering each atrium from the veins
-one way valves
-cardiac suction effect
-cardiac contraction
-sympathetic vasoconstrictor
-skeletal muscle pump
-respiratory pump
-blood volume

Question 35

How does gravity affect venous return? What measures help compensate for the effect of gravity?

Answer 35

Pressure of the weight of the blood moved down
1. fall in mean arterial pressure triggers sympathetic vasoconstriction of veins –> increased venous return
2. movement of skeletal muscle squeezes veins, breaks up the column of blood so less blood weight bears down on lower veins

Question 36

What are baroreceptors? Could you identify how the firing rate of a baroreceptor would change for increased or decreased blood pressure?

Answer 36

-A sensory receptor cell that produces graded receptor potentials in response to mean arterial blood pressure

Question 37

What effect does parasympathetic activity have on blood pressure? How about sympathetic activity? Does parasympathetic activity directly cause changes to blood vessels? How about sympathetic activity?

Question 38

What is hypotension?

Answer 38

Blood pressure too low (<90/60 mm Hg)

Question 39

What is hypertension?

Answer 39

Blood pressure is too high (> 140/90 mm Hg)

Question 40

What is the difference between secondary and primary hypertension?

Answer 40

Secondary- hypertension caused by a known pathology (10% of cases)
Primary- hypertension with unknown causes (90% of the time)

Question 41

What are some consequences of long-term hypertension?

Answer 41

-Stroke
-Heart attack
-Kidney failure