A&P: Cardiovascular system; Blood Vessels

Question 1

Tunica intima

Answer 1

Innermost
Endothelium
Makes contact with blood

Question 2

Tunica media

Answer 2

Middle
Smooth muscle
Elastin: allows arteries to recoil
Arteries have thicker tunica media than veins (arteries are higher pressure)

Question 3

Tunia externa (adventitia)

Answer 3

Outermost
Collagen fibers (reinforces blood vessel)
Vaso vasorum: in larger vessels (nourishes external tissues of blood vessel wall)

Question 4

Elastic (conducting) arteries

Answer 4

Thick-walled
Largest diameter/ closest to heart
Low resistance
Pressure reservoirs

Question 5

Muscular (distributing) arteries

Answer 5

Majority
Thickest tunic media of all vessels
More active in vasoconstriction and less distensible

Question 6

Arterioles

Answer 6

Smallest type of artery (feeds into capillary bed)

Question 7

Capillary

Answer 7

Smallest blood vessel
Microcirculation: gas and hormone exchange between blood and interstitial fluid
Only has tunica intima
Pericytes: cells on outside of capillary that help anchor capillary to surrounding area and control permeability
Tight junctions

Question 8

Continuous capillary

Answer 8

Most common
Tight junctions are very tight
Epithelial cells are continuous
Intercellular clefts: limited passage of fluids and small solutes

Skin, skeletal muscles

Question 9

Fenestrated capillary

Answer 9

Holes/pores covered with diaphragm
Much more permeable to fluids and solutes
Found wherever active absorption or filtrate formation occurs

Kidneys (filtration), lower GI tract (esp. small intestine)

Question 10

Sinusoids/ Sinusoidal capillary

Answer 10

Highly modified, leaky capillaries
Large, irregularly shaped lumens (fenestrated); discontinuous epithelium
Stellate macrophages
Found in tissues that have to clean blood

Liver, bone marrow, spleen, and adrenal medulla

Question 11

Capillary bed

Answer 11

Area where oxygen-rich and oxygen-poor blood meet
Vascular shunt (metarteriole-thoroughfare channel): direct connection between arteriole and venule
True capillaries: surrounds vascular shunt; exchange vessels
-Pre-capillary sphincters: smooth muscle; contract/ relax to change flow of blood into capillary bed
Creates more direct route for blood flow

Question 12

Venule

Answer 12

Small vein

Capillaries unite to form a venule

Question 13

Vein

Answer 13

Blood to heart
Venules join to form veins
Thinner walls and larger lumens compared to arteries 
Blood reservoirs
Low pressure
Low resistance
Venous valves: prevent backflow of blood
   Most abundant in veins of limbs

Question 14

Blood flow

Answer 14

Volume of blood flowing through a vessel, organ, or entire circulation in a given period
Equivalent to CO
Dependent upon pumping action of heart

Question 15

BP

Answer 15

Force blood exerts on vessel wall by blood

Systemic arterial bp is largest is arteries near the heart

Question 16

Peripheral resistance

Answer 16

Friction
Creates/increases pressure
Affects BP
Affected by total blood vessel length and diameter
Longer the vessel, greater the resistance
Smaller the diameter, greater the resistance
Viscosity: lower viscosity –> lower resistance

Question 17

MAP

Answer 17

Mean arterial pressure
General average of pressure in arteries
Pressure that propels blood to tissues

Question 18

Venous BP

Answer 18

Stable: changes very little during cardiac cycle
Adequate venous return
-Skeletal muscle pump: skeletal muscles pump blood back up to heart (valves in veins prevent backflow)
-Respiratory pump: blood in thorax; inhalation –> diaphragm moves down, increasing pressure in abdominal cavity and decreasing pressure in chest cavity
-Venoconstriction: SNS; contraction of veins (reduced BV)

Question 19

Velocity of Blood flow

Answer 19

Inversely related to total cross-sectional area of vessel
Larger cross-sectional area, slower the blood flow
Capillaries have slowest velocity

Question 20

Metabolic control

Answer 20

Stimuli: chemical
   -Low oxygen levels
   -High H+ 
   -Inflammatory chemicals
Trigger release of nitric oxide --> vasodilation

Endothelins: secreted by endothelium –> vasoconstriction

Question 21

Tissue Perfusion: Skeletal muscle

Answer 21

Active

NE: vasoconstriction of tissue not needed for exercise

Question 22

Tissue Perfusion: Brain

Answer 22

Relatively constant
Increasing CO2 (not eliminating waste from area)
   -Vasodilation

Decreasing MAP (pressure decreases)
   -Vasodilation

Circle of Willis: at base of brain; interconnection of blood vessels that serve cerebrum

Question 23

Tissue Perfusion: Heart

Answer 23

Constant at rest
Bloodflow through myocardium stops during ventricular systole
-Myoglobin: found in muscles and carries oxygen
-Allows myocardiocytes to survive
Blood flow continues duinr ventricular diastole
-Ventricles relax; myocardium receives normal blood supply

Exercise: vasodilation of coronary arteries

Question 24

Blood Flow: Capillaries

Answer 24

Intermittent flow due to:

• Vasomotion
• Movement of solutes
• Bulk fluid flow
  
  • Hydrostatic pressure
  • Colloid pressure

Question 25

Circulatory Shock

Answer 25

Inadequate blood flow

Question 26

Hypovolemic shock

Answer 26

Blood volume or bodily fluids drop relatively quickly
BP drops
Heart pumps faster

Question 27

Vascular shock

Answer 27

Normal BV

Circulation poor due to extreme vasodilation