tunica media-middle layer

thickest layer, composed of elastic tissue and smooth muscle.

made up of elastic tissue and smooth muscle, capable of stretching in response to the pumping of blood by the heart

tunica adventitia- the outer layer

composed of tough connective tissue, function is to support and protect.

arterioles

the smallest artery, numerous and branch out

capillaries

smallest and most numerous of all blood vessels

close to every cell, numerous, provide the cells with oxygen and nutrients

arterioles

smallest of the arteries

• composed of smooth muscle that contact and relax
• have the thinnest walls of all blood vessels

veins

• blood vessels that carry blood back to the heart
• smallest veins are called venules
• the largest veins empty the blood into the right atrium of the heart

venules

converge from capillaries

wall of venule is slightly thicker than capillary wall

aorta

• largest of all arteries
• average diameter of a garden hose

SYSTEM I, path that the aorta follows as it courses through the body

1. ascending aorta
2. arch of the aorta
3. descending aorta

SYSTEM II, path named according to location within the body cavities

1. thoracic aorta
2. abdominal aorta

left common carotid artery

extends upward from the highest point of the aortic arch and supplies the left side of the head and neck

left and right subclavian arteries

supply blood to the shoulders and upper arms

superficial veins

located superficially and can be seen

deep veins

located more deeply and usually run parallel to the arteries

superior venae cava

veins draining blood from the head, the shoulders, and the upper extremities empty into the SVC

Junglar veins

main brain to drain the brain

portal vein

a large vein that carries blood from the organs of digestion to the liver

the liver

• the largest organ In the body
• essential for keeping the body functioning properly

the livers function

• removes poisons from the blood
• produces immune agents to control infection
• removes germs and bacteria in the blood

splanchnic circulation

blood flow to the stomach, spleen, pancreas, intestines and liver

blood vessels functions

1. acts as a delivery system
2. regulate blood pressure
3. redistribute blood in response to changing body needs
4. help regulate body temperature

5 cool P's of occlusive arterial disease

• pain. diminished oxygen supply stimulates pain receptors
• pulselessness. the blocked artery decreases the flow of blood to the extremity; the pulse distal to the occlusion is diminished or absent
• pallor. due to lack of blood the extremity is pale, especially when elevated
• paresthesia. diminished blood flow decreases the supply of oxygen to the nerves of the leg, causing numbness and tingling.
• paralysis. persistent oxygen deficit causes permanent nerve damage and paralysis (late sign)

three mechanisms assist in the return of venous blood

1. skeletal muscle action
2. respiratory movements
3. constriction of ht veins

skeletal muscle action

large veins in the legs are surrounded by skeletal muscles

factors affecting vascular resistance

• sympathetic nerve activity
• various hormones
• pharmacologic agents

lymphoid organs

• lymph nodes
• tonsils
• thymus gland
• spleen

lymph nodes

small pea-shaped patches of lymphatic tissue strategically located so as to filter the lymph as it flows through the lymphatic vessels

axillary lymph nodes

located in the axillary or armpit. drain and cleanse lymph coming from the upper extremities, shoulder, and breast area

inguinal lymph nodes

located in the groin region. drain and cleanse lymph from the lower extremities and external genetalia

tonsils

partially encapsulated lymph nodes in the throat area

pharyngeal tonsils

located near the opening of the nasal cavity in the upper pharynx

lingual tonsils

located at the back of the tongue

thymus gland

located in the upper mediastinum in thoracic cavity

thymosins

hormone secreted by the thymus gland

spleen

largest lymphoid organ in the body

• filters blood rather than lymph

immunity

defense system

functions of the immune system

• protect the body from pathogens
• protect the body from foreign agents

non-specific immunity

protects the body against different types of foreign agents

mechanical barrier

intact skin and mucous membrane. pathogens cannot cross these structures to enter the body

chemical barriers

secretions of the skin and mucous membranes

second line of defense

• phagocytes
• inflammation
• fever
• protective proteins
• natural killer cells

phagocytosis

WBC'S ingest and destroy pathogens and other foreign substances

inflammation

responses the body makes when confronted by an irritant

infection

if an irritation is caused by a pathogen, the inflammation is called an infection

macrophages

big eaters