The Circulatory System Flashcards
What is the purpose of the circulatory system?
Facilitates the transport of materials within the internal environment for exchange with cells through structure and function.
What is the purpose of the lymphatic system?
To collect escaped fluid from blood capillaries and return it to the circulatory system.
Plays an important role in the body’s internal defense and resistance against disease-causing organisms.
What are the main components of the circulatory system?
The heart, blood vessels, blood, the chambers, the valves.
What is the function of the blood vessels?
Blood is pumped by the heart into the blood vessels, which carry the blood to the cells of the body/lungs and bring it back to the heart again.
- Deliver oxygen and nutrients to cells
- Carry away waste products from cells
- Part of maintaining blood pressure
What is the function of blood?
- Transport
- Regulation
- Protection
How does the blood provide transport?
Transports nutrients and oxygen to all cells of the body as well as transporting carbon dioxide and other waste products away from the cells.
It transports chemical messengers, called hormones to the cells.
How does the blood provide regulation?
It distributes heat to help in regulating the body’s temperature and pH of body fluids
How does the blood provide protection?
Prevents blood loss by clotting if blood vessels are damaged. It also protects the body against pathogens, toxins and disease-causing micro-organisms.
What is the function of the right side of the heart?
The right side of the heart makes up the pulmonary circuit. It collects deoxygenated from the heart and pumps it into the lungs
What is the function of the left side of the heart?
It makes up the systemic circuit. It receives oxygenated blood from the lungs and pumps it to the rest of the body.
What is the right atrium?
The receiving chamber for deoxygenated blood that has been through the capillaries of the body.
What is the function of the right ventricle?
Pumps blood to the lungs. Its wall is thinner that the left ventricle wall because not as much force is required to push blood to the lungs.
What is the left atrium?
The receiving chamber for blood from the lungs. Pushes blood into the left ventricle
What is the left ventricle?
Has a thick muscular wall for pumping blood into the aorta and out the body.
What is the pulmonary trunk?
Divides into two pulmonary arteries that carry deoxygenated blood to each lung.
What is the function of semilunar valves?
Prevent backflow of blood from arteries to ventricles.
What is the function of the pulmonary vein?
Brings oxygenated blood to the heart from the lungs
What are the atrioventricular valves?
- Between the atria and the ventricle.
- Flaps of thin tissue with the edges held by tendons called chordae tendinae.
- Prevents backflow of blood from the ventricles to the atria
How does blood become deoxygenated?
As oxygenated blood flows through the capillaries of the body, oxygen and nutrients diffuse from the blood into the body cells, and carbon dioxide and other wastes diffuse from the cells and into the blood, becoming deoxygenated.
How does blood become oxygenated?
As deoxygenated blood flows through the capillaries of the lungs, oxygen diffuses from the air into the blood and carbon dioxide diffuses from the blood into the air, becoming oxygenated.
What are the main components of blood?
- Plasma (55%)
- Erythrocytes (RBCs - 41%)
- Leucocytes (WBCs)
- Thrombocytes (Platelets)
What is plasma?
A mixture of water with dissolved substances such as sugar and salts.
What is the function of plasma?
To transport components of blood, including cells, nutrients, wastes, hormones, proteins and antibodies throughout the body.
What are erythrocytes?
- Account for approximately 40-45% of its volume.
- Biconcave shape – flattened in the middle on both sides.
- Don’t contain a nucleus increasing their flexibility and ability to move through blood vessels.
- The lack of a nucleus limits their life span to only 120 days on average.
What is the function of a red blood cell?
To transport oxygen from the lungs to the cells throughout the body.
What do erythrocytes contain?
Haemoglobin is a protein molecule specifically designed to hold oxygen and carry it to cells that need it.
What are leucocytes?
- WBCs that protect the body from infection.
- Make up 1% of the blood, white blood cells are larger than red blood cells.
What are the main types of white blood cells?
- Macrophages
- Lymphocytes.
What is the role of macrophages?
They engulf and digest micro-organism by phagocytosis.
What happens during phagocytosis
- Projections from macrophages surround the particle and take it into the cell, where it is destroyed by enzymes.
- Most bacteria ingested in this way are killed within 10 to 30 minutes.
What is the role of lymphocytes?
Some lymphocytes fight disease by making antibodies to destroy invades by dissolving them, others make antitoxins to break down poisons.
What are thrombocytes (platelets)?
- Very small cell fragments with no nucleus.
- They are about one-third the size of a RBC
- They are formed in the red bone marrow and last about 7 days.
- Important for normal blood clotting.
What is the role of thrombocytes?
When a blood vessel gets damaged, platelets stick to the inside and create a net of fibrinogen. This helps the blood to clot..
What are the main types of blood vessels?
- Arteries
- Capillaries
- Veins
What are arteries?
An artery is a blood vessel that carries deoxygenated blood away from the heart, under high pressure.
Describe the structure of an artery
The wall of an artery contains smooth muscle and elastic fibres - can stretch to accommodate the extra blood when ventricles contract.
When the ventricles relax, the elastic walls recoil, allowing the blood to flow under high pressure.
The arterioles in large arteries contain smooth muscles, important for regulating blood flow through the capillaries.
The smooth microscopic lumen allows for efficient blood flow.
Provide 2 examples of an artery
- Aorta (largest)
- Pulmonary artery
What are veins?
Veins are blood vessels that carry blood towards the heart.
Made up of capillaries that join into small veins known as venules which join up to make larger veins.
What are the characteristics of veins?
Veins carry deoxygenated blood to the heart at low pressure - lumen is large.
Veins are less muscular, with less elastic fibres because the blood pressure is relatively low.
Blood loses most pressure as it flows through capillaries.
The pressure is constant, so the walls aren’t elastic.
Because of this pressure, veins have valves that prevent the backflow of blood.
Provide two examples of a vein
- Inferior vena cava
- Superior vena cava
- Pulmonary veins
What are capillaries?
Capillaries are the link between the arteries and the veins.
What are capillary properties?
Microscopic blood vessels form a network to carry blood to cells in the body.
Enables cells to get requirements needed from blood and pass waste into the blood.
Capillary walls are one cell thick, allowing diffusion, movement and the transport of substances to and from the plasma to happen.
What is the heart?
A hollow muscular pump that moves blood throughout the body. It lies in the chest cavity behind the breastbone and slightly to the left
What are the two loops?
Blood flows along two pathways in the body with both pathways converging at the heart.
- Pulmonary Circuit
- Systemic Circuit
What happens in the pulmonary circuit?
The right side of the heart forms the pulmonary circuit, from the lungs and back
Carries deoxygenated blood from the heart to the lungs.
Blood picks up oxygen from the air and releases carbon dioxide to the air.
Oxygenated blood then returns to the heart to be pumped around the body.
What happens in the systemic circuit?
The left side of the heart forms the systemic circuit, from the heart to the body and back.
Carries oxygenated blood from the heart to the rest of the body.
Blood releases oxygen to the body cells and picks up carbon dioxide from the cells.
Deoxygenated blood then returns to the heart to be pumped to the lungs.
What are the semilunar valves?
Valves between the:
- Right ventricle and pulmonary artery
- Left ventricle and aorta
What are the atrioventricular valves?
Separates the atria from the ventricles
What is blood pressure?
The resulting force that the blood exerts on the artery walls. When ventricles contract, they create pressure
What is blood pressure used for?
To drive blood through the body via arteries and capillaries
How is blood pressure measured?
- mm of mercury (mmHg)
- represented by 2 numbers separated by a slash
What are the two types of blood pressure?
- Systolic
- Diastolic
What is systolic pressure?
- The highest pressure in an artery
- Produced when the ventricles contract
What is diastolic pressure?
- The lowest pressure in artery
- Produced when the ventricles relax
What does haemoglobin do in the blood?
Increases oxygen carrying capacity by 60-70 times.
When does oxygen combine with HB?
When the oxygen concentration is high in the lung capillaries
When does the HBO2 break down?
When the oxygen concentration is low
- tissue fluid around cells
What colour is HBO2?
Bright red, so arterial blood is also bright red.
What colour is HB?
Bright blue/purple so venous blood is also darker
How is carbon dioxide carried?
8% of carbon dioxide is dissolved in plasma.
22% binds with haemoglobin to form carbaminohaemoglobin
70% is carried in plasma as bicarbonate ions (HCO-3).
Carbon dioxide diffuses into the plasma and reacts with water to form carbonic acid (H2CO3), which breaks down into hydrogen and bicarbonate ions.
In the alveoli, carbon dioxide diffuses out of the blood and the carbaminohaemoglobin breaks down, releasing more carbon dioxide.
How is oxygen carried in the blood?
3% of oxygen is dissolved in plasma.
97% is transported as oxyhaemoglobin, which forms when oxygen levels are high in the lung capillaries.
Loose combination, allowing easy release of oxygen into tissues where concentrations are low.
Haemoglobin increases blood’s oxygen-carrying capacity by 60-70 times.
What are two ways blood clotting helps small injuries to blood vessels?
- Muscles in the walls of the damaged arteries constrict.
- The internal wall of the damaged vessel is rough, causing thrombocytes to stick to it and form.
How does blood clotting happen?
Threads of insoluble proteins called fibrin trap blood cells, thrombocytes and plasma.
What are clot retractions?
Contractions of the fibrous threads of a blood clot which pulls the damaged blood vessels together.
What are blood groups?
The differences in human blood due to the presence/absence of antigens/antibodies
Where are antigens and antibodies located?
- Antigens = surface of red blood cells
- Antibodies = plasma
What are antigens and antibodies?
A substance that can stimulate the production of antibodies.
Antibodies combine with the antigen to destroy it
What is blood group A?
- A antigens
- B antibodies
What is blood group B?
- B antigens
- A antibodies
What is blood group AB?
- A/B antigens
- Neither antibodies
What is blood group O?
- Neither antigens
- A/B antibodies
Blood group O is known as?
Universal donors
Blood group AB is known as?
Universal receivers
How are transfusions successful?
If the recipient doesn’t have antiobdies against the donor’s antigens. If so, the RBCs in the donated blood with clump (agglutination).
What is agglutination?
When blood reacts with the antibodies. No agglutination means the blood doesn’t have any antigens binding to the antibodies.
What happens to a person with the Rh protein?
A person with Rh antigens is said to be Rh positive.
These individuals cannot produce an anti-Rh antibody.
They are known as universal receivers.
They can receive blood from someone with Rh- blood.
What happens to a person without the Rh protein?
A person without these antigens is Rh negative.
An individual without the Rh antigens is able to produce an anti-Rh antibody that reacts against those antigens.
They are also called universal donors and can never receive blood from someone with Rh+ blood.
What are the effects of incompatible blood types being given to people?
A transfusion can only work if a person who is going to receive the blood has a blood group that doesn’t have any antibodies against the donor blood’s antigens.
If the man were to receive an AB or A transfusion, then his A antibodies would react with the A antigen in AB blood.
This will cause the red blood cells to clump together, or agglutinate.
