CV V

Question 1

How does increasing sarcomere length increase force of contraction (SV)

Answer 1

1. Increases Ca sensitivity (decreased diameter reduces distance Ca must diffuse)
2. Additional tension on Ca channels, increases Ca entry from ECF and Ca induced Ca release

Question 2

What is Frank-starling law of heart

Answer 2

Amount of force developed by cardiac muscle of ventricle (indicated by SV) depends on initial stretch of ventricle walls (cause by ventricle filling)
SV increases with increasing EDV

Question 3

Preload

Answer 3

Degree of myocardial stretch prior to contraction
EDV

Question 4

What is EDV determined by

Answer 4

Venous return

Question 5

What does increased venous return increase

Answer 5

Increases venous pressure resulting in increased atrial filling leading to increased ventricle filling

Question 6

What are 3 factories affecting venous return

Answer 6

1. Skeletal muscle pump
2. Respiratory pump
3. Sympathetic constriction of veins

Question 7

Skeletal muscle pump

Answer 7

Skeletal muscle activity compresses veins in extremities pushing blood back
Increases venous return

Question 8

Repiratory pump

Answer 8

During inspiration chest expands, diaphragm moves down creating sub atmospheric pressure in thoracic cavity
Creates sumbatmospheric pressure in vena cava and draws blood
Veins are compressed during inspiration

Question 9

Sympathetic constriction of veins

Answer 9

Decreases their volume squeezing blood back to heart

Question 10

After load

Answer 10

End load against which the heart contracts to eject blood
- blood in ventricle must eject enough pressure to push blood in outflow artery farther down circuit

Question 11

What is afterload determined by

Answer 11

EDV and pressure in outflow artery prior to contraciton

Question 12

How can afterload be increased

Answer 12

In pathological situations
Increased arterial BP, decreased aortic compliance

Question 13

How does blood pressure affect afterload

Answer 13

If heart working harder, heart muscle hypertrophies
Loses elasticity, compresses coronary arteries
Reduces volume

Question 14

What is pressure reservoir of systemic circuit

Answer 14

Aorta and large arteries

Question 15

How do arterials alter their diameter

Answer 15

Adjustable screws allow variable resistance

Question 16

Where does the exchange between blood and cells take place

Answer 16

Capillaries

Question 17

What do arterioles do

Answer 17

Divergence

Question 18

What do venues do

Answer 18

Converge until reach single vessel

Question 19

What serves as an expandable volume reservoir

Answer 19

Systemic veins

Question 20

What is the progressive branching of vessels

Answer 20

Aorta - arteries - arterioles - capillaries - venules - veins - vena cava

Question 21

What do all vessels contain

Answer 21

Inner layer of thin endothelial cells

Question 22

What is order of layers of vessels

Answer 22

Lumen - endothelium - elastic tissue - smooth muscle - fibrous tissue

Question 23

What are endothelial cells important for

Answer 23

Secreting paracrine, regulation of BP, blood vessel growth, absorption of materials

Question 24

Paracrines

Answer 24

Substances that signal changes in near by cells

Question 25

What are capillaries composed of

Answer 25

Single thin endothelium Basal lamina coats outside (extracellular matrix)

Question 26

What is artery composed of

Answer 26

All 4 More elastic tissue and smooth muscle than vein

Question 27

What is arterioles composed of

Answer 27

Endothelium, Smooth muscle

Question 28

What is venule composed of

Answer 28

Endothelium, fibrous tissue

Question 29

What is vein composed of

Answer 29

All 4 Larger volume Less elastic tissue and smooth muscle than arteries Have valves More expandable

Question 30

What is vascular smooth muscle topically controlled by

Answer 30

Sympathetic input Always state of partial contraction

Question 31

What is vascular smooth muscle influenced by

Answer 31

Neurotransmitters hormones, paracrines Cause increased Ca so contraction

Question 32

Arteries

Answer 32

Walls that are both stiff and springy

Question 33

Micro circulation

Answer 33

Arterioles, capillaries, venules

Question 34

What is across microcirculation

Answer 34

Met arterioles

Question 35

What are metarterioles

Answer 35

Precapillary sphincters Act as capillary bypass vessels For blood and WBC’s

Question 36

What are the smallest vessels in the CV system where majority of exchange between blood and interstitial space occur

Answer 36

Capillaries

Question 37

How are gasses moved in across endothelial cells of capillaries

Answer 37

Passively diffuse

Question 38

How are small solutes and water transported around endothelial cells of capillaries

Answer 38

They are linked by interendothelial junctions

Question 39

What are fenestrations

Answer 39

Membrane lined conduits running though endothelial cells to allow transport

Question 40

What are capillaries surrounded by

Answer 40

Pericytes, prevent substance readily from moving in Ex) BBB

Question 41

Continuous capillary

Answer 41

Most common - thick endothelial cells, basal lamina - no fenestrations - only passage of water and small ions through intercellular junctions

Question 42

Fenestrated capillary

Answer 42

Thin endothelial cells with fenestrations Where high transport needed Small molecule passage

Question 43

Discontinuous (sinusoidal) capillary

Answer 43

No basal membrane Large open fenestrations Gaps between endothelial cells Transport large molecules Ex) liver, spleen, bone marrow

Question 44

Transcellular transport

Answer 44

Diffusion or osmosis across endothelial cell membrane - gases, small lipid molecules, water, glucose

Question 45

Paracellular

Answer 45

Diffusion through interendothelial junctions, pores or fenestrations - water, small water soluble and small polar molecules

Question 46

Transcytosis

Answer 46

Combination of receptor mediated endocytosis, vesicular transport, exocytosis - macromolecules across endothelial cells