Lecture 32: Blood Vessels and blood (Reading 1)

Arteries do what with blood

Take blood away from heart

Veins do what with blood

Take blood to the heart

Pressure is

Force exerted by blood

Bulk Flow

The volume of blood flowing through the circuits (pulmonary & systemic) each minute

Flow

the volume of blood flowing through a vessel each minute

How does blood flow

High to low

What does resistance do to flow

Hinders it

What factors affect the resistance of blood flow

Blood volume radius, Blood volume length, and blood viscosity

is the pressure greater in systemic or pulmonary circuit

systemic circuit

is the resistance greater in the pulmonary or systemic circuit

systemic circuit

isovolumetric

pump same amount of blood in each circuit per beat

where is the endothelium located

Tunica interna

Fxn of endothelium

lines the lumen

where is the smooth muscle located of artery

tunica media

Where is the connective tissue of artery located

tunica externa

2 subunits of connective tissue of artery

collagen fibers & elastin fibers

2 Functions of arteries

carry oxygenated blood away from the heart & serve as pressure reservoirs and conducting arteries

what innervates the smooth muscle of the arterioles

sympathetic nervous system

what region of the brain do the sympathetic fibers of the arterioles

Cardiovascular control center in the medulla

High metabolic activity causes vasoconstriction or vasodilation

Vasodilation

low metabolic activity causes vasodilation or vasoconstriction

vasoconstriction

During exercise, to which organs or tissues does blood flow increase?

skeletal & cardiac muscle

what organ decreases blood flow in exercise

GI tract

What does epinephrine or norepinephrine bind to in arteriolar smooth muscle

Alpha- one or Beta-two adrenergic receptors

What happens when epi/NE binds to Alpha-one receptors

Constriction of the arterioles

What happens when epi/NE binds to Beta-two receptors

Dilation of the arterioles

which adrenergic receptors activate the IP3 system

Alpha-one

Which adrenergic receptor activates cAMP system

Beta-two

Mean arterial pressure

Average blood pressure in a person’s arteries during one cardiac cycle

What are the three types of capillaries

Continuous, fenestrated, and sinusoidal.

what are the two layers in continuous capillaries

Endothelial cell layer and basement membrane

What types of molecules can pass through continuous capillaries?

Small, polar, and lipophilic molecules.

Where are fenestrated capillaries located

kidney, intestines, and endocrine organs

what are fenestrated capillaries

pores in capillaries, that are small, polar, and lipophilic

Sinusoid are located

spleen, bone marrow, and liver.

Bone-marrow makes

Red blood cells

In sinusoid what can pass through

Whole cells

If capillaries can’t change diameter, how is blood flow regulated?

By precapillary sphincters

What happens when the precapillary sphincter is open (relaxed)

Blood flows into capillary bed

What happens when the precapillary sphincter is closed (contracted)

Blood does not flow into capillary bed

After the blood has entered the capillary bed, what does it allow

It allows the exchange of gases, nutrients, and wastes

When the precapillary sphincter is closed, where does blood go after its past the capillary bed

the blood is shunted through the thoroughfare channel

What is the throughfare channel

A direct way from arteriole to venule used when the capillary bed is bypassed