Blood Vessels Flashcards
Pulmonary Circulation
Deoxygenated blood carried away from the heart by pulmonary artery.
Oxygenated blood carried to the heart by pulmonary veins.
Systemic Circulation
Oxygenated blood carried away from the heart by arteries.
Deoxygenated blood carried to the heart by veins.
Arteries
Always carry blood away from the heart.
Pulmonary arteries are the exception - all carry oxygenated blood
Thick, muscular walls
Aorta is the largest artery – first artery through which blood in the systemic system flows through on leaving the heart.
The aortic arch
The two regions are the ascending aorta, and the descending aorta – important arteries branch off the aortic arch:
The carotid arteries – carry blood to the head
The subclavian arteries – carry blood to the arms
The abdominal aorta
Located on the left side of the body
The important arteries that branch of the abdominal aorta are:
The ciliac artery - carries blood to liver stomach and spleen
The renal arteries – carry blood to kidneys
The iliac arteries – carry blood to legs (via the femoral arteries)
Veins
Always carry blood back to the heart (except for pulmonary veins – veins, carry deoxygenated blood)
Veins have thinner walls than arteries
The vena cava
Superior vena cava - collect blood from upper body and head, short vein
Inferior vena cava – collect blood from lower body, long vein, located on right side of body
Capillaries - definition
This is where exchange of gases (oxygen and carbon dioxide) and chemicals take place between the blood and the interstitial tissue
Venules
These are the narrowest type of vein and receive deoxygenated blood from the capillary bed
Blood flow through the capillary bed
Pre-capillary sphincters control the flow of blood from the ateriole into each capillary
When one pre-capillaries sphincter constricts, blood is diverted into all the branches of the network, when it relaxes blood flows into the capillary
Each pre-capillaries, sphincter, alternately, contracts and relaxes, altering vessel diameter - vasomotion
Low, oxygen concentration is enhance relaxation – auto regulation
Veso vasorum - blood supply to the blood vessel walls
Walls of arteries and large veins are too thick to allow diffusion between bloodstream and tissues of the vessel.
So, the walls of large vessels contain small arteries and veins that supply the cells of the tunica media and tunica externa. These blood vessels are called the vaso vasorum.
What is the correct order of the blood vessels through which blood passes if travelling from the heart to the liver and back again?
Left ventricle, aorta, ciliac artery, hepatic artery, arteriole, capillary, venule, hepatic vein, inferior vena cava, right atrium
Cellular structure of a blood vessel
All vessels consist of 3 layers
Tunica intima (inner layer) - endothelia line the blood vessel
Tunica media (middle layer) - vascular smooth, muscle cells, collagen, and elastin fibres, often the thickest layer
Tunica adventita (outer layer) - outer protective layer, fibroblasts
Arteries compared to veins
Arteries have thick are more muscular walls with an enlarged tunica media layer
Elastic arteries
Arteries close to the heart must be able to expand and recoil in order to maintain a constant blood pressure throughout the heartbeat cycle – they contain a large number of elastic fibres (collagen and elastin) to do this
Examples
Aorta, pulmonary artery, subclavian, artery, carotid artery
Muscular arteries
Elastic arteries branch into smaller muscular arteries, and these contain fewer elastic fibres but more smooth muscle
Muscular arteries are able to actively regulate blood flow to meet demand by muscular contraction
Examples
Coronary arteries, femoral arteries
Arterioles
The tunica media of arterioles is one or two muscle cells thick
Vasodilate at low oxygen, vasoconstrict under sympathetic stimulation
More pressure is required to push blood through a constricted vessel than through a dilated one. The force opposing blood flow is called resistance hence why arterioles are known as resistance vessels.
Capillaries - continuous
Most capillaries in the body
Very restricted permeability
Permits exchange of water, small, solutes, and lipid-soluble materials between the blood and interstitial fluid
Capillaries - fenestrated
Facilitate the rapid exchange of water and solutes between blood and interstitial fluid
Capillaries - sinusoid
Free exchange of water, solutes and large plasma proteins
Defenestration is the act of throwing someone out of a window but which class of blood vessel, sometimes contains windows?
Capillaries
Vasculogenesis
Refers to the formation of entirely new blood vessels
This occurs only during embryonic development
Angiogenesis
Refers to the sprouting of new branches from pre-existing blood vessels
This process occurs throughout life example, new capillaries will develop in your muscles if you train
Atherosclerosis
Refers to the buildup of fatty deposits within the walls of arteries
These can trigger clot formation become dislodged, blocking arteries
Can cause heart attacks, strokes, kidney disease
