Circulatory Flashcards
Arteries
- thick blood vessels that carries blood away from the heart
- every time the heart contracts, blood surges from the heart and enter the arteries
-the arteries stretch order to accommodate the inrush of blood
-each organ in the body is supplied with one or more arteries
How are arteries adapted to withstand the pressure?
-have the thickest walls composed of distinct layers
- outer and inner layers of connective tissue
-middle layer of muscle fibres and elastic connective tissue
What is the pulse that you feel?
It is created by the changes in diameter of the arteries following heart contractions
What is the Tunica Externa?
The tough outer layer of connective tissue in the arteries
Tunica media
Thick Layer of smooth Muscle and elastic fibres composed of the protein elastin
Tunica intima
Smooth endothelium that lines the interior of the artery
Lumen
The inside space of a tubular structure, usually artery or vein
In the tunica media, what does the elastin do?
Elastin is organized into fenestrated cylindrical lamellae and is separated by other lamellar layers by smooth muscle. As it is stretched, it stores this energy and then recoils back to help propel the blood through the artery
In the tunica media, what does the smooth muscles do?
Contraction of the smooth muscle in the artery controls the diameter of the lumen as well as the rigidity, regulating flow
What does the tunica external do?
Helps prevent aneurisms and bursting due to high pressure
How is the progress of blood along the major arteries?
Artery walls work with the pumping of the heart to facilitate blood flow, the progress of blood along major arteries is pulsatile! The pulse reflects each heart beat.
Pulsatile: beating or moving with a strong regular rhythm, especially in the way that the heart beats
How does the contractions and relaxations of the arteries reflect the heart beat?
The peak pressure in an artery (SYSTOLIC PRESSURE) is associated with the CONTRACTION of ventricles of the heart. This causes the lumen to widen and stretched the elastic fibres in the wall, storing potential energy
Following this contraction, RELAXATIONS of the heart muscles results in the lowest pressure and is referred to as DIASTOLIC PRESSURE. The stored potential energy is released through the restoration of elastic fibres to their original position, driving the blood forward through the vessel.
This saves energy and prevents pressure within the artery from becoming too low. Pressure in the arteries are maintained so the blood flow is relatively steady and continuous even with a pulsating heart beat.
Vasoconstriction
A nerve impulse causes smooth muscle in the arteries to contracts, reducing the diameter of the blood vessel and blood flow to tissues.
Can be regulated with hormons
Vasodilation
Relaxation of the smooth muscle causes dilation of the arterioles, blood flow increases and there is an increases in the delivery of blood to tissues. This, in turn, permits the cells in that localized area to perform energy-consuming tasks
Can be regulated by hormones
Arterioles
Smaller arteries essentially
As blood passes from the arteries, they flow into arterioles
Their structure is similar to arteries, with a middle layer composed of elastic fibres and smooth muscle
Arterioles leading to capillaries are only open when the cells in that area requires blood
What regulates the diameter of arterioles
Automatic Nervous System
____________________ is responsible for redness in skin due to blushing
Vasodilation-increase in blood flow to capillaries helps to release excess heat
______________ is responsible for paleness due to being frightened
Vasoconstriction- decrease in blood flow to outer capillaries and diverted to muscles, provide more energy and gluscose to muscles
Capillaries
-connect arterioles to venules
- composed of a single layer of endothelium cells and the narrowest blood vessels in the body
-only one red blood cell through at a time
-site of fluid and gas exchange (consists of several branches to increase surface area for gas and fluid exchange - branch and rejoin repeatedly to form a capillary network)
- spaces exist where vitamins and minerals can be exchanged
Tissue Fluid
When plasma leaks through into the tissues
Contains dissolved oxygen, glucose and other substances to nourish cells in three tissues.
As the tissue fluid flows between the cells in these tissues, waste products excreted by these cells are absorbed and taken away as the tissue fluid flows reenters the capillary network
Weaknesses of Capillaries
Supseptible to damage by pressure or trauma because of how thin they are
Permeability of Capillary Walls
-differs a,longstanding different tissues, selectively allowing certain large particles to reach certain tissues and not others. Permeability can also change over time and the capillaries can be repaired and remodelled in response to the needs of tissues
Atherosclerosis
Excess lipids in the blood can be deposited in the walls of the arteries-narrows the inside diameter of arteries
Deposition of calcium and minerals results in a plaque being formed
Results in HIGH BLOOD PRESSURE
If the plaque grows so big that it bursts the artery wall, clotting could result in the blockage of artery, which could lead to a heart attack.
Atheroma
The development of fatty tissue occurs within the endothelial layer (adjacent to the artery wall)
