Blood Vessels

What are the 3 parts that make up the Cardiovascular System

• heart

• blood

• blood vessels

blood vessels

• made up of what

• how long

• made of living cells

• 60k miles long

3 kinds of blood vessels and their function

• arteries- carry blood away from heart to tissues

• veins- carry blood toward heart

• capillaries- smallest microscopic blood vessels where exchange of blood & tissue occurs

which blood vessel is the only one with valves & why

• veins

• valves in veins help prevent backflow

3 layers of artery walls

1. tunica interna- innermost

2. tunica media- middle

3. tunica externa- outermost

tunica interna

• position

• what tissue

• innermost lining

• endothelial cells (simple squamous epithelial tissue)

tunica media

• position

• what tissue

• for what

• middle lining

• smooth muscle tissue

• for vasoconstriction & vasodilation

tunica externa

• position

• what tissue & for what

• outermost lining

• collagen fibers for strength

Arterial System

• define

• what is its thickest layer

• what do all layers have

• high pressure system

• its thickest layer is the tunica media

• all layers have elastic fibers

3 parts of the Arterial System

1. Elastic Arteries

2. Muscular Arteries

3. Arterioles

Elastic Arteries:

• size

• function

• ex

• largest diameter

• function: conduct arteries

• ex: aorta & pulmonary arteries

Muscular Arteries

• size

• function

• example

• middle diameter

• function: distributing arteries

• ex: radial & brachial arteries

Arterioles

• size

• function

• smallest diameter

• function: resistance vessels

Tunica Media

• main function

• allows muscular arteries to?

• allows arterioles to?

• allows muscular arteries & arterioles to constrict & dilate.

  • Muscular arteries can then regulate blood flow into arterioles inside specific organs. 

  • Arterioles can then regulate blood flow into capillaries.

• Define capillaries

• what’s their diameter?

• & what are their walls made of?

  • why?

• exchange vessels

• 5-10 micrometers

• walls made of tunica interna

  • thin walls allow for rapid exchange

How big are capillaries

What are clefts?

Gaps in capillaries between neighboring cells

What are the 3 kinds of Capillaries?

1. Continuous Capillaries

2. Fenestrated Capillaries

3. Sinusoids

Continuous Capillaries:

• permeability

• abundance

• location

• least permeable

• most abundant capillaries

• location: our skin & muscles

Fenestrated Capillaries

• permeability & why

• 2 locations & function

• very permeable bc it has pores

• locations:

  • small intestine for rapid nutrient absorption

  • kidneys membrane for rapid filtration

Sinusoids

• have what 2 things

• 3 locations & their function

• large pores & clefts

  • red bone marrow- forms blood cells

  • spleen- macrophages lysis old rbcs

  • liver- macrophages break down bacteria

What is Capillary Exchange?

• movement of substances between plasma & interstitial fluid

What 3 events is Capillary Exchange aided by?

1. Diffusion

2. Transcytosis

3. Bulk Flow

Diffusion

• ATP need?

• what does it do

• passive= does not need ATP

• moves small nonpolar molecules high to low (i.e. o2 and co2)

Transcytosis

• ATP need?

• what does it do

• Active=needs ATP

• vesicles are used to transport substances across cell

Bulk Flow

• ATP need?

• what does it do & why

• Passive= does not need ATP

• solutes & particles in fluid move together bc of pressure differences in capillary wall

What 2 things occur in Bulk Flow & describe

• Filtration- fluids leave plasma & enter interstitial fluid 

• Reabsorption- fluids leave interstitial fluid and enters plasma

What 3 pressures affect bulk flow?

• Hydrostatic Pressure

• Osmotic Pressure

• Net Filtration Pressure

Hydrostatic Pressure

• define

• #s where

• it is the force exerted by fluid against a wall

• 35 mm of Hg (mercury) in beginning of capillary, 16 Hg in end of capillary

Osmotic Pressure

• define

• # & describe it

• force that opposes hydrostatic pressure bc of non diffusing molecules (proteins!)

• 26 mm of Hg (mercury)does not change, stays same throughout capillary

Net Filtration Pressure

total pressure that promotes filtrations

When is Net filtration positive and when is it negative?

• NFP is + in filtration

• NFP is - in absorption

• Where does Filtration occur & NFP #

• Where does Reabsorption occur & NFP #

• Filtration- occurs in capillary start

  • NFP= +10mm Hg

• Reabsorption- occurs in capillary end

  • NFP= -9mm Hg

3 characteristics of the Venous System

• lowest pressure sys

• has thin walls & wider lumens than arteries

• acts as a blood reservoir (*65% total blood volume)

What is the thickest layer in the Venous System?

tuna externa

What 3 parts does the Venous System consist of & compare their diameters

• Venules (smallest diameter)

• Venous Sinuses (middle diameter)

• Veins (largest diameter)

2 examples of veins

Superior & Inferior Vena Cava

What are Venous Sinuses?

specialized broad (sack-like) veins supported by surrounding tissue

What are Venules?

• blood vessels that

  bring blood from capillaries to veins

What is the tunica in the Venous Sinus?

Only the Tunica Interna

What are 2 examples of Venous Sinuses & their function?

• Coronary Sinus- returns blood coming from myocardium 

• Dural Sinus- returns cerebrospinal fluid from the CNS