Chapter 19 Flashcards
What is a closed system?
What gets pumped out gets pumped back
What are the 3 major types of blood vessels?
Artery, capillary, and vein
What is an artery?
Carries blood away from heart
What is the capillary?
Exchange nutrients and waste
What is a vein?
Carries blood towards the heart
What are the 3 tunics vessels are made of?
Tunica intima, media, and externa
Properties of the tunica intima?
Lines lumen wall.
Simple squamous endothelial layer.
Forms smooth layer (decrease in friction).
Subendothelial layer: basement membrane.
Present in al l vessels; thin flat layer.
Properties of the tunica media?
Thickest layer.
Smooth muscle and elastin connective tissue.
Vasoconstrict or vasodilate.
Epinephrine.
Not present in all vessels.
Properties of the tunica externa?
Outermost layer.
Loose collagen connective tissue.
Nerves and lymph vessels.
Vasa vasorum: blood vessels that carry nutrients.
What does the lymphatic system do?
Takes fluid lost from capillaries and brings back to cardiovascular system
How does blood get around restricted blood vessels?
Anastomoses
What are anastomoses?
Very prominent in capillaries.
Alternate pathways.
What are collateral channels?
Natural bypass; when artery develops second route to get them from point A to point B
What is the distribution of blood in the cardiovascular system when at rest?
Systemic arteries and arterioles: 15%
Pulmonary blood vessels: 12%
Heart: 8%
Capillaries: 5%
Systemic veins and venules: 60%
Properties of elastic (conducting) arteries?
Thick-walled arteries near the heart.
Large lumen: low-resistance to flow.
Contain elastin.
Smooth out large blood pressure fluctuations.
Serve as pressure reservoirs.
Always blood in the blood vessels.
Properties of muscular arteries?
Distal to elastic arteries; deliver blood to body organs.
Have thick tunica media with more smooth muscle.
Active in vasoconstriction.
Branching off aorta.
Can withstand high pressures.
Properties of arterioles?
Smallest arteries; lead to capillary beds.
Control flow into capillary beds (resistance vessels).
Resistance vessels.
Greatest resistance in cardiovascular system.
Branch and branch and branch.
Have all 3 tunics.
Properties of capillaries?
Smallest blood vessels.
Thin tunica interna (only).
Nutrient exchange takes place here.
Large surface area.
3 structural types.
What is the biggest elastic artery?
Aorta
Properties of continuous capillaries?
Abundant in the skin and muscles.
- endothelial cells provide uninterrupted lining.
- adjacent cells are connected with tight junctions.
- clefs allow small things to pass through.
Continuous capillaries of the brain:
- tight junctions completely around the endothelium.
- thick basal lamina.
- blood-brain barrier: continuous capillary with tons of tight junctions; restricts crossing of fluids and nutrients.
Properties of fenestrated capillaries?
Found wherever capillary absorption occurs.
Endothelium with pores.
Greater permeability
Properties of sinusoids?
Leaky, fenestrated capillaries with large lumens.
Liver, bone marrow, lymphoid tissue, and some endocrine organs.
Allow large molecules to pass between blood and surrounding tissues.
Very large clefts.
What are capillary beds?
Microcirculation of interwoven networks of capillaries
What does a precapillary sphincter do?
Prevent blood flow into the capillaries when constricted
When do sphincters relax?
When tissues need more nutrients
What direction is blood carried towards in the venous system?
Towards the heart
What are venous capillaries?
Formed when capillary beds unite.
Porous.
What are postcapillary venules?
Smallest venules, composed of endothelium and a few pericytes
What are large venules?
One or two layers of smooth muscle (tunica media)
Properties of veins
Formed when venules converge.
Composed of 3 tunics: tunica intima, thin media, and thick externa.
What valves do veins have?
one-way
What is blood flow?
Volume of blood flowing through a vessel
What is blood pressure?
Force exerted per unit area on a vessel wall (mmHg); arterial pressure; pressure differences (gradient).
What is resistance?
Opposition to flow (peripheral resistance), viscosity, vessel length and vessel radius
What is viscosity?
Measure of the resistance of a fluid
What is blood vessel radius?
1/2 the diameter
What is systolic blood pressure?
Pressure exerted by the blood on the blood vessel walls during ventricular contraction.
ex. peak blood pressure in the aorta.
What is diastolic blood pressure?
Pressure exerted by the blood on the blood vessel walls during ventricular relaxation.
ex. the pressure necessary to open the aortic valve.
What is pulse pressure?
Difference between systolic and diastolic pressure
Pulse pressure equation?
Pulse pressure = SBP - DBP
What is mean arterial pressure (MAP)?
Pressure that propels the blood to the tissues
MAP equation?
MAP = diastolic pressure + 1/3 pulse pressure
MAP = diastolic pressure + 1/3 (SBP-DBP)
What are the main factors influencing blood pressure?
Cardiac output (Q)
Peripheral resistance (R)
Blood volume
Blood pressure equation
Blood pressure = cardiac output x resistance
Blood pressure = Q x R
What does blood pressure vary directly with?
Q, R, and blood volume
What is the maintenance or modulation of blood pressure?
- Q
- Vastone
- Plasma volume
What are the controls of blood pressure?
- Short-term
- neural
- hormonal
- humeral - Long-term
- neural regulation
Neural: vasomotor control
SNS.
Receptors: alpha1 and beta2.
Baroreceptors. (pressure-sensitive)
Chemoreceptors. (CO2 and H+ sensitive)
Higher brain centers. (hypothalamus)
Hormonal control
Vasoconstriction:
- catecholamines
- ang II
- endothelium-derived factors
Blood volume:
ADH and ANP
Humeral control
Vasodilation:
- nitric oxide
- inflammatory chemicals
- increase in K+
- increase in CO2
- increase in H+
How do long-term controls control blood pressure?
alter blood volume
