BLOOD VESSEL CHAPTER20

Systemic Circuit

Carries blood throughout body to supply oxygen and nutrients to tissues

Pulmonary Circuit

Larger loop that carries blood to the lung for gas exchange

Arteries/Artery

Cary blood away from the heart

Branch to form arterioles

Venules and Veins

Carry blood back toward heart

Venules and Veins

Exposed to lower pressures

Capillaries

are the sites of exchange

Lumen

Space blood flows

Valves

ensures one-way flow

Tunics

blood vessel walls

tunica intima

innermost layer

Atherosclerosis

tendency for blood to clot

prone of clotting

lamina

internal elastic membrane

Large arteries

not found in veins

provides additional elasticity

Tunica media (middle layer)

mainly smooth muscle

Tunica externa (outermost)

mainly of collagen

maintains structure of vessel

Vasa vasorum

supplied by larger arteries and veins

Arteries

away from the heart

oxygenated

Elastic arteries

higher percentage of elastic fibers

help propel blood

muscular arteries

higher percentage of smooth muscle

controlling distribution of blood

arterioles

Microscopic arteries

very thin

greatest resistance to blood flow and blood pressure

capillaries

thin-walled vessels

used for exchange between blood and tissue

continuous

most common type, complete

allows exchange of water

fenestrated

found in small intestine & kidneys

contain pores in endothelial lining

allows exchange of fluid

sinusoid (al)

found in liver

least common

large gaps

allow exchange of plasma proteins and cells

metaterioles

regulate flow of blood into capillary beds

located at openings of capillary beds

sphincters

contract to limit blood flow

venules

extremely small veins

veins

toward the heart

thinner walls than arteries

artery-arteriole-capillary bed-venule-vein

Typical pattern of blood flow:

arterial anastomosis

multiple arteries

provides alternate routes

venous anastomosis

venule split, contribute to multiple veins

portal system

links two capillary beds

blood flow

movement of blood through the body

arterial blood pressure

measured using a sphygmomanometer at the brachial artery

Systolic pressure

ventricular systole

Diastolic pressure

ventricular diastole

pulse pressure

difference between systolic and diastolic pressure

ex: 120/80

120-80=40 the answer

mean arterial pressure

“average” pressue, calculated

pulse

the expansion

cardiac output

amount of blood rejected

blood volume

amount of blood within vascular

poiseville’s equation

relates resistance to blood flow

blood vessel length, blood viscosity etc.

Blood Viscosity

The thickness of blood

blood vessel radius

inversely proportion to resistance

vessel radius

most important influence on resistance

compliance

to expand

blood velocity

speed of flow

hypertension

defined by high blood pressure greater than 140/90

ductus venosus

bypass liver

epinephrine and novepinephrine

increase BP via increased CO

Aldosterone

increases blood volume to increase BP

Atrial natriuretic hormone

decreases blood volume to decrease BP

parasympathetic

if BP is too high

sympathetic

if BP is too low

baroreceptor reflexes

balancing the BP if its too high or too low

vasomotor

control vascular tone

cause vasoconstriction (vasodilation)

Cardioinhibitory

decrease HR

via parasympathetic

cardioaccelerator

regulate heart rate HR

increase HR

lymphatic capillaries

absorb excess to prevent edema