Saladin Chapter 20

blood vessels

form a closed system of tubes that carry blood, oxygen, and nutrients to the body

blood vessels consist of

3 layers called tunics

tunic layers of the blood vessels

tunica interna, tunica media, tunica externa

tunica interna (intima)

forms the thin, inner lining of blood vessels and comes in DIRECT contact with the blood

tunica that is made up of simple squamous epithelium known as endothelium

tunica interna

the endothelium of the tunica interna

acts as a selectively permeable membrane, secretes chemicals that can dilate or constrict the blood vessels, and repels blood (so no clots form)

tunica media

forms the thick, middle layer of the blood vessels that consists of smooth muscle

primary function of tunica media

to contract in order to regulate blood flow and blood pressure (vasomotion)

vasomotion

contraction in order to regulate blood flow and pressure

tunica externa (adventitia)

outer most covering of a blood vessel

primary function of tunica externa

to anchor the blood vessels to surrounding tissues/structures

layer of the blood vessels that contain nerves and tiny blood vessels that supply the blood vessel tissue

tunica externa

vaso vasorum

blood vessels for blood vessels

types of blood vessels

arteries, veins, capillaries

arterial vessels

carry blood away from the heart

veins

carry blood to the heart

capillaries

responsible for gas exchanges

arterial vessels from largest to smallest

conducting (elastic) arteries, muscular (distributing) arteries, arterioles, metarterioles

largest of the arterial vessels

conducting/elastic arteries

the aorta is an example of

conducting artery

conducting arteries

have numerous elastic fibers and help to propel blood away from the heart

muscular/distributing arteris

distribute blood to specific organs

arterioles

are very small branches from the distributing/muscular artery

metarterioles

short vessels that link arterioles with capillaries

anastomoses

the union of branches of two or more arteries supplying the same region of the body

most tissues receive blood supply from more than one artery because

multiple routes means multiple ways to circulate the blood

capillaries

are microscopic blood vessels that connect arterial outflow from the heart to venous return to the heart

primary function of capillaries

to exchange oxygen and nutrients between the blood and tissues

most capillaries use

simple diffusion to exchange materials

the exchange vessels of the cardiovascular system

capillaries

filtration

movement of fluid from capillaries to interstitial space

reabsorption

movement of fluid from interstitial space to capillaries

the venous vessels from largest to smallest

veins, venules

how much blood is found in the veins at any given moment

over half

venules

receive blood from capillaries

when many venules come together

vein

veins have the presence of

valves

valves

prevent the backflow of blood

muscle contractions are used

to help push the blood back up the veins to the heart

arteries have

thick walls, thick muscle layer, carry blood from the heart, no valves

veins have

thin walls, thin muscle layer, carry blood toward the heart, valves

blood flow

the volume of blood that flows through any tissue, organ or blood vessel in a given period of time

blood pressure

the force exerted by blood on the walls of a blood vessel

blood pressure is created by

the contraction of the ventricles

normal adult blood pressure

120/80 or less

the top number

systolic or the highest pressure that occurs during contraction

the bottom number

diastolic or the lowest pressure that occurs during rest

increased blood volume would

increase bp

increased sympathetic stimulation would

increase bp

increased parasympathetic stimulation would

decrease bp

increased heart rate would

increase bp

decreased heart rate would

decrease bp

increased cardiac output would

increase bp

decreased cardiac output would

decrease bp

systolic bp

number when you first hear a heart beat

diastolic bp

number when you can no longer hear the heart beat

hypertension

chronic resting bp of 140/90 or higher

hypotension

chronic low resting bp

main factors that affect blood pressure

peripheral resistance, blood viscosity, vessel length, vessel radius

peripheral resistance

the friction caused by blood flow

increased peripheral resistance

increased bp

blood viscosity

thickness of the blood

increased blood viscosity

increased bp

decreased blood viscosity

decreased bp

vessel length

the longer the blood vessel, the more friction it will encounter

increased vessel length

increased bp

decreased vessel length

decreased bp

vessel radius

half the diameter of a vessel

vasoconstriction

decreasing the diameter of a vessel

vasodilation

increasing the diameter of a vessel

vasoconstriction causes

increased bp

vasodilation causes

decreased bp

laminar flow

blood closest to the vessel walls move slower than the blood in the middle

systemic circulation

movement of blood from the heart to the body and back again

pulmonary circulation

movement of the blood from the heart to the lungs and back again

aorta

largest artery of the heart

aortic arch branches

brachiocephalic trunk, left common carotid artery, left subclavian artery

branches of the brachiocephalic trunk

right sublclavian artery and right common carotid artery

the carotid arteries branch into numerous smaller arteries that supply

the head, neck, brain

the subclavian arteries branch into smaller arteries that supply

the upper limbs

thoracic aorta

part of aorta that is in the thorax

abdominal aorta

part of the aorta that is in the abdomen

the abdominal aorta gives off a

external iliac artery that gives off several branches that supply the lower extremities

the superior vena cava

receives blood from the head, neck, and upper extremities

the inferior vena cava

receives blood from the abdominopelvic region and lower extremities

aneurysm

where a bulging sac is created at a weak point in an artery wall. . .can eventually lead to a rupture

varicose veins

due to hereditary causes, prolonged standing; the valves in the veins become weaker, allowing blood to pool in the lower extremities

TIA

mini stroke; stroke-like event whose symptoms last less than 24 hours and usually don't cause permanent brain damage

stroke

caused by a blood clot blocking an artery in the brain, leading to death of brain cells and brain damage

arteriosclerosis

hardening of the artery walls

atherosclerosis

build up of fats/cholesterols on the walls of the arteries