Vessels and Circulation

Tunica Intima

Deepest layer of blood vessel

Tunica media

Middle layer of blood vessel

Tunica externa

Outermost layer of blood vessel

Vaso vasorum

small arteries require to supply very large vessels

Capillaries

exchanges substances between blood and tissues

Arteries have a thick…

tunica media

Arteries have narrow

lumens

Veins have thicker

tunica externa

veins have large

lumens

Elastic (conductiong) artery

largest arteries

includes the aorta, pulmonary trunk etc.

Muscular (Distributing) Artery

Medium arteries

1cm to 3mm

Muscular arteries include

brachial artery, coronary artery

Arterioles

smallest arteries

3mm to 10 micrometers

Continuous capillaries

capillary cells that form a continuous capillary

tight junction capillaries (small things can pass through)

found in muscle, skin, lungs

Fenestrated capillaries

capillary cells that have pores

allows movement of fluids

found in intestine, kidneys

fenestrations are also known as

pores

Sinusoidal

capillaries with large pores and incomplete linings

found in bond marrow, spleen, glands

branched structures that supply nutrients and remove waste from tissues

capillary beds

sphincters in capillary beds can prevent blood from

entering/occluding the capillary

what percent of blood is in systemic circulation

70%

Arterial anastomosis

occurs when two or more arteries converge to supply the same region

Venous anastomosis

occurs when two or more veins drain the same body region

Arteriovenous anastomosis

known as a shunt

transports blood from the artery directly to the vein

Portal system

when two capillary beds are in one sequence of blood vessels

what type of circulation pathway does not go through a capillary bed

arteriovenous anastomosis

Blood moves faster through

larger vessels

Vascular tone

The smooth muscle in arteries that makes them always slightly constricted

the nervous system and sympathetic receptors control

blood vessel diameter

hormones that can control vessel diameter

epinephrine , norepinephrine

blood vessel _____ do not have impacts on blood flow, but the size of their _____ does

walls , lumen

Bulk flow

fluids flowing down a pressure gradient

Filtration

fluid and small substances moves out of capillaries

occurs on arterial end of capillary

Reabsorption

fluid moves back into blood

occurs on venous end

Hydrostatic pressure

force exerted by a fluid (blood presure)

Colloid osmiotic pressure

the pull on water due to the presence of protein solutes

Net filtration pressure

the difference between net hydrostatic pressure, and net colloid osmotic pressure

when hydrostatic pressure is greater than net colloid osmotic pressure

filtration occurs

when hydrostatic pressure is lower than net colloid osmotic pressure

reabsorption occurs

the system that picks up excess fluid not reabsorbed at venous capillary end

lymphatic

Blood pressure

Systolic pressure / diastolic pressure

Pulse pressure

the difference between systolic and diastolic blood pressure

Mean arterial pressure

average arterial blood pressure across entire cardiac cycle

In capillaries blood flow..

no longer fluctuates between systolic and diastolic

flow and pressure are smooth

In veins blood pressure..

is low and not pulsatile

Skeletal muscle pump

assists venous return from limbs when you move your muscles

blood pools in veins with prolonged inactivity

Pressure gradient

continually decreasing pressure of a BV as the diameter of the vessels lumen increases.

Inspiration

abdominal pressure increases and thoracic pressure decreases, moving blood into the thoracic cavity

Expiration

thoracic pressure increases while abdominal pressure decreases. blood moves toward the heart

Total blood flow

the amount of blood moving through the system per unit of time

Systemic blood pressure gradient

as the pressure gradient increases, total blood flow increases

Resistance

the friction blood encounters

Peripheral resistance

the resistance of blood in blood vessels

long blood vessels create

more resistance

Local control of blood pressure

vasodilation through paracrine mechanisms

Neutral control of blood pressure

‘short term’ control

pressure monitored by baroreceptors

Hormonal control of blood pressure

hormones elicit changes by regulating blood volume

Aldosterone

tells the kidneys to retain sodium to increase BP

ADH

tells the kidneys to retain water to increase BP

Atrial Natriuretic Peptide (ANP)

tells kidneys to secrete sodium (anti-aldosterone) to decrease BP