UNT 2 - KA5 Flashcards
What are all components of blood carried around in
All of the components of blood are carried around the body in different types of blood vessels
What are the three main types of blood vessel found in the body
- arteries
- capillaries
- veins
What are the 4 main points about Nat 5 arteries vs veins (blood pressure and direction)
Artery - much thicker muscular wall than veins, carry blood at high pressure , narrower central channel, carry blood away from the heart
Vein - thinner muscular wall than artery, carry blood at low pressure towards the heart, wider central channel, carry blood towards the heart
What do veins contain which arteries do not
Veins also contain structures called valves - these prevent the back flow of blood and ensure it only travels in one direction
What is the cycle of blood circulation (think acv)
Blood circulates from the heart through the arteries to the capillaries then to veins and back to the heart. There is a decrease in blood pressure as blood moves away from the heart
What happens to blood pressure as it moves away from the heart
Decreases
What does pulmonary circulation relate to
Pulmonary circulation relates to the lungs
How does the pulmonary artery differ from all other arteries in the body
It is unusual as arteries usually carry oxygenated blood whereas the pulmonary artery carries deoxygenated blood from the heart to the lungs where it picks up oxygen
How does the pulmonary vein differ from all other veins in the body
The pulmonary vein carries oxygenated blood from the lungs to the heart this is unusual because most veins carry deoxygenated blood
What is the function of the coronary arteries
The coronary arteries supply the cardiac muscle of the heart with blood containing glucose and oxygen
Blood vessel - artery
Arteries have an outer layer of connective tissue containing elastic fibres and a middle layer containing smooth muscle with more elastic fibres.
Blood vessel - vein
Veins have an outer layer of connective tissue containing elastic fibres but a much thinner muscular wall than arteries. They contain valves to prevent the back flow of blood
Blood vessel - capillary
Capillaries allow exchange of substances with tissues through their thin walls
What is the benefit of the thick muscular wall in arteries
Thick muscular wall helps withstand pressure of heart pumping
What is the endothelium surrounded by
The endothelium lining the central lumen of blood vessels is surrounded by layers of tissue
What is the role of the elastic walls of arteries
The elastic walls of the arteries stretch and recoil to accommodate the surge of blood after each contraction of the heart
What can the smooth muscle in arteries do
The smooth muscle can contract or relax causing vasoconstriction or vasodilation to control blood flow
What is the role of the central lumen
Central lumen of an artery is where the blood flows through - this is relatively narrow
What type of wall do capillaries have
Each capillary has a very thin wall called the endothelium (only one cell thick)
What does the endothelium of a capillary line
Lines the central lumen of the capillary
What are capillaries the site of
Capillaries are the site of material exchange
What type of blood vessels can carry out vasoconstriction and vasodilation
Arteries
What can happen to the smooth muscle surrounding arteries to control blood flow
To control blood flow the smooth muscle surrounding arteries can contract causing vasoconstriction or relax causing vasodilation
What do capillaries allow
Capillaries allow exchange of substances with tissues through their thin walls
What are arterioles and venules
- smaller/narrower arteries
- smaller/narrower veins
Describe a functional difference between arteries and veins
- arteries carry blood that is oxygenated/HIGH BP
- Veins carry blood that is deoxygenated/low BP
Vasodilation
During strenuous exercise arteries leading to working muscles undergo vasodilation. This allows an increase in blood flow to the skeletal muscles involved in strenuous exercise
Vasoconstriction
At the same time arteries leading to abdominal organs such as the small intestine undergo vasoconstriction. This reduces blood flow to these organs during the period of strenuous exercise
Why can arteries carry out vasoconstriction and vasodilation
Muscular walls thicker than veins
Where do capillaries exist
Capillaries exist in a dense network called a capillary bed
What is exchanged in capillary beds
It is here that gases, nutrients and waste materials are exchanged with tissue cells
What is everybody cell near and bathed in
Every body cell is near a capillary and constantly bathed in a liquid called tissue fluid
What is pressure filtration
When blood arrives at the arteriole end of a capillary bed, High pressure forces the plasma through the thin walls of the capillaries into the tissue fluid surrounding the cells
How many substances are forced through capillary walls
Most of the dissolved substances in the plasma are also forced through the capillary walls.
Which molecules remain behind in the plasma
Only the large protein molecules, and blood cells of course remain behind in the plasma
What does tissue fluid supply cells with
Tissue fluid supplies body cells with glucose, oxygen and other substances down the concentration gradient
Which substances diffuse out of the cells into the tissue fluid
Carbon dioxide and other metabolic wastes diffuse out of the the cells and into the tissue fluid to be excreted in the opposite direction
What happens to blood pressure at the venule side of capillary bed
At the venule side of the capillary bed the blood pressure has fallen
What happens to the tissue fluid at the Venule side of the capillary bed
Here much of the water In the tissue fluid returns to plasma by osmosis. At the same time carbon dioxide and additional waste products enter the plasma by diffusion
What happens to excess tissue fluid
lymphatic vessels absorb excess tissue fluid and return it as lymph to the circulatory system
How much of the tissue fluid returns to the bloodstream
Not all the tissue fluid returns to the bloodstream in the capillaries
What is the composition of tissue fluid and blood plasma
Tissue fluid and blood plasma are similar in composition with the exception of plasma proteins, which are too large to be filtered through the capillary walls
