ch5 circulatory system Flashcards
(118 cards)
1
Q
Define:
Circulatory system
A
The link between the cells inside the body, which have certain requirements, and the environment outside the body, which supplies those requirements.
2
Q
Blood functions
A
- Transporting oxygen and nutrients to all cells of the body
- Transporting carbon dioxide and other waste products away from the cells
- Transporting chemical messengers, called hormones, to the cells
- Maintaining the pH of body fluids
- Distributing heat and maintaining body temperature
- Maintaining water content and ion concentration of the body fluids
- Protecting against disease-causing micro-organisms
- Clotting when vessels are damaged, thus preventing blood loss.
3
Q
Blood components
A
- Plasma: liquid part, making up ~55% of the blood volume
- Formed elements: non-liquid part ~45% of the blood volume
- Erythrocytes (red blood cells)
- Leucocytes (white blood cells)
- Thrombocytes (platelets)
4
Q
***** Plasma structure and function
A
A mixture of liquid and dissolved substances such as sugar and salts.
Transport the components of blood, including
5
Q
Define:
Erythrocytes (RBC)
State function and abundance
A
The most abundant cells in the blood, whose purpose is to transport oxygen to cells. Accounts for 40-45% of the blood volume
This percentage is called the haematocrit.
6
Q
Erythrocytes structure
A
- Biconcave (flattened in the middle on both sides)
- Don’t contain a nucleus
- Increases flexibility and, hence, their ability to move through blood vessels.
- But, lack of nucleus limits lifespan to around 120 days.
7
Q
Leucocytes (WBC) function and abundance.
A
Protect the body from infection. Only 1% of the blood volume.
8
Q
Types of leucocytes.
A
- Neutrophils
- Monocytes
- Lymphocytes
- Basophils
- Eosinophils
9
Q
Neutrophils function
A
Contain enzymes to digest pathogens
10
Q
Monocytes function
A
Form other cells, including macrophages.
11
Q
Macrophages function
A
Engulf pathogens and aged/damaged cells through phagocytosis.
12
Q
Lymphocytes function
State two types
A
Involved in immune response.
* T-lymphocytes
* B-lymphocytes
13
Q
T-lymphocytes function
A
Involved in cell-mediated immunity.
14
Q
B-lymphocytes function
A
Involved in antibody-mediated immunity
15
Q
Basophils function
A
Involved in allergic reactions — they produce heparin and histamine to defend the body against parasites and bacteria.
16
Q
Eosinophils function
A
Lead inflammatory responses — they respond to larger parasites such as worms.
17
Q
Thrombocytes structure and function
A
Small fragments of cells. When a blood vessel is injured, they adhere to the lining and form a scaffold for the coagulation of blood to form a clot.
18
Q
What are the two ways oxygen is transported in the blood?
A
- 3% is carried in solution in plasma
- 97% is carried in red blood cells as oxyhaemoglobin
19
Q
How is oxygen transported in red blood cells?
A
Haemoglobin combines with oxygen to form a compound called oxyhaemoglobin.
This happens when the oxygen concentration is relatively high.
Oxygen concentration is high in the capillaries in the lungs, where oxygen diffuses into the blood from the air in the alveoli.
Oxyhaemoglobin can easily break down to release the oxygen.
This happens when the oxygen concentration of relatively low.
As the cells of the body are continually using oxygen, the tissue fluid around the cells has a relatively low oxygen concentration. Therefore, when red blood cells flow through the capillaries between body cells, they give up their oxygen, which diffuses into the tissue fluid and then into the cells.
20
Q
What colour is oxygenated blood and why?
A
Oxyhaemoglobin is bright red, so the blood in the arteries (except the pulmonary arteries taking blood to the lungs) is bright red.
21
Q
What colour is deoxygenated blood and why?
A
Haemoglobin is dark red or purplish, so the deoxygenated blood in the veins (except the pulmonary veins from the lungs) is dark red.
22
Q
Why are red blood cells well suited to transport oxygen?
Structure
A
01. contain haemoglobin
which is able to combine with oxygen.
02. have no nucleus
so there is more space for haemoglobin molecules.
03. are shaped like biconcave discs
the biconcave centre increases the surface area for oxygen exchange and the thicker edges give a large volume that allows space for the haemoglobin molecules.
23
Q
What are the three ways carbon dioxide is transported in the blood?
A
- 7-8% is dissolved in plasma and carried in solution.
- 22% is carried as carbaminohaemoglobin.
- 70% is carried in plasma as bicarbonate ions (HCO₃⁻)
24
Q
How is carbon dioxide transported between the blood and lungs?
A
As blood is flowing through the capillaries between body cells, carbon dioxide diffuses into the plasma due to the difference in carbon dioxide concentration (low in plasma, high in body cells).
- Some carbon dioxide dissolves in the plasma
- Some combines with haemoglobin
- Most reacts with water to form carbonic acid (H₂CO₃)
- Carbonic acid then ionises into hydrogen ions and bicarbonate ions
Recall: alveoli are highly vascularised - they are surrounded by a dense network of capillaries.
Carbon dioxide dissolved in the plasma diffuses out of the blood (from capillary) into the air in the alveolus.
→ Hydrogen ions and bicarbonate ions recombine to form carbonic acid.
→ Carbonic acid then breaks down under enzyme actin into water and carbon dioxide.
→ This carbon dioxide also diffuses into the alveolus.
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How are nutrients and waste transported in the blood?
In the blood plasma.
26
# Define:
Nutrients
The essential elements and molecules that are obtained from the food we eat.
27
# List:
Inorganic nutrients
- sodium
- calcium
- potassium
- chloride
- iodide
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# List:
Organic nutrients
- glucose
- vitamins
- amino acids
- fatty acids
- glycerol
29
# Define:
Metabolic wastes
Substances produced by cells that cannot be used and would be harmful if allowed to accumulate.
30
# List:
Metabolic wastes
- urea
- creatinine
- uric acid
31
Vasoconstriction definition and purpose
| during injuries
Muscles in the walls of the small arteries that have been injured or broken constrict immediately.
*Purpose: reduce blood flow, and therefore, blood loss.*
32
Platelet plug definition and purpose
Damage creates a rough surface on internal walls of blood vessels to which the platelets can stick. Sticking platelets attracts more platelets, and so a plug is build up at the site of the injury.
*Purpose: reduce blood loss.*
*This plugging and blood vessel constriction is enough to stop any bleeding for very small tears in capillaries.*
Platelets also release substances that act as vasoconstrictors.
*Purpose: enhance and prolong the constriction of the damaged vessels.*
33
Coagulation (blood clotting) definition and purpose
The series of chemical reactions causes the formation of threads of fibrin: an insoluble protein.
The fibrin threads form a mesh that traps blood cells, platelets, and plasma. This mesh, with its trapped material, is the clot or thrombus. The threads stick to the damaged blood vessels and hold the clot in position.
*Purpose: prevent excessive bleeding when a blood cell is injured.*
| Involves clotting factors present in plasma.
34
# Define:
Heart
The (four-chambered) pump that pushes blood around the body.
35
Heart location
Between the two lungs in the mediastinum, behind and slightly to the left of the sternum.
36
Heart shape and size
Conical shape, approximately 12cm long, 9cm at its widest point and 6cm thick.
37
Heart membrane
Holds the heart in place, but also allows it to move as it beats. It also prevents the heart from overstretching.
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Heart wall structure
Made up of cardiac muscle.
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Heart septum
The wall that separates the left and right sides of the heart.
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Heart right side function
Collects blood from the body and pumps it to the lungs (to get oxygenated).
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Heart left side function
Receives blood from the lungs (oxygenated) and pumps it to the rest of the body.
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Heart chambers
*Each side of the heart is also divided into two chambers — two chambers per side = four chambers.*
**Atria (single: atrium)**: top chambers.
**Ventricles**: bottom chambers.
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Atria function
Collect blood from the body and lungs.
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Ventricles function
Pump blood out of the heart to the lungs and body.
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Right atrium function
Receives blood from the body and passes it to the right ventricle.
46
Right ventricle function
Pumps blood to the lungs.
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Left atrium function
Receives blood from the lungs and passes it to the left ventricle.
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Left ventricle function
Pumps blood to the body.
49
Why is the wall of the left ventricle thicker?
It needs to be much stronger to pump blood through the blood vessels supplying the body.
50
Purpose of the valves in the heart
To ensure that blood can only flow in one direction.
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Atrioventricular valves definition and purpose
* Valves between the atria and ventricles — purpose is to stop blood from flowing back into the atria.
52
Atrioventricular valves structure and how it works
* Flaps of thin tissue with the edges held by tendons - called chordae tendineae - that attach to the heart on papillary muscles.
* When the ventricles contract, the blood catches behind the flaps and they billow out like a parachute, sealing off the opening between the atria and ventricles.
* Blood must then leave the heart through the arteries and not flow back into the atria.
53
Semilunar valves definition and purpose
Valves where the arteries leave the heart — purpose is to stop blood from flowing back into the ventricles when the ventricles relax.
54
Semilunar valves structure and how it works
Each semilunar valve has three cusps.
When blood flows into the artery, the cusps are pressed flat against the artery wall.
When blood tries to flow back into the ventricle, the cusps fill out and seal off the artery, ensuring that blood only flows in one direction.
55
# Define:
Blood vessels
Blood is pumped by the heart into the blood vessels, which carry blood to the cells of the body or the lungs, then bring it back to the heart.
56
# Define:
Arteries
Blood vessels that carry blood away from the heart.
57
Aorta
The largest/main artery, which takes blood from the left ventricle to all parts of the body (except the lungs).
58
Pulmonary artery
Artery that takes blood from right ventricle to lungs.
59
Arteries structure.
Thick, muscular, elasatic walls
- smooth muscle
- elastic fibres
No valves.
60
How do ventricles move blood?
* When ventricles contract and push blood into the arteries, the walls of arteries stretch to accommodate the extra blood.
* When the ventricles relax, the elastic artery walls recoil.
* Elastic recoil keeps the blood moving and maintains the pressure.
61
How do arteries affect blood movement?
The muscle in the artery walls does not contract and relax to pump the blood along, but the muscle can contract to reduce the diameter of the artery and thus reduce blood flow to an organ.
62
# Define:
Vasoconstriction
The contraction of an artery to reduce blood flow to an organ.
63
# Define:
Vasodilation
The relaxation of an artery to increase blood flow to an organ.
64
What do arterioles do?
Have smooth muscle in their walls, and contraction/relaxation of this muscle is very important in regulating blood flow through the capillaries.
65
What do lactic acid and carbon dioxide do?
Act as vasodilators
66
# Define:
Vasodilators
Substances that produce local widening, or dilation of arterioles, leading to increased blood flow through the muscle tissues, ensuring cells are supplied with adequate oxygen and nutrients for continued functioning
67
# Define:
Capillaries
Microscopic blood vessels that form a network to carry blood close to nearly every cell in the body.
68
Capillary structure
- walls only have one layer of cells (one cell thick)
- this allows substances to pass easily between the blood and surrounding cells
- increases rate of diffusion because substances have a shorter distance to travel
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Veins
Carry blood towards the heart.
70
Pressure in the arteries
Pressure increases as the ventricles contract and decreases as the ventricles relax.
71
Veins structure.
Thin, relatively inelastic walls with little muscle. Often have valves.
72
# Define:
Blood
The transport medium that delivers oxygen and nutrients to cells and carries away wastes.
73
# Define:
Cardiac cycle
The sequence of evens that occurs in one complete beat of the heart.
74
Systole
The pumping phase of the cycle, when the heart muscle contracts.
75
Diastole
The filling phase, as the heart muscle relaxes.
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Function of the right side of the heart
Receives deoxygenated blood from cells around the body and sends it to the lungs
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Function of the left side of the heart
Receives oxygenated blood from the lungs and sends it to cells around the body.
78
Cardiac output
| Definition + formula
The amount of blood leaving one of the ventricles every minute.
cardiac output (mL/min) = stroke volume (mL) × heart rate (beats/minute)
79
# Define:
Stroke volume
Volume of blood forces from a ventricle of the heart with each contraction.
80
Antigens
Sugar and protein molecules that are able to stimulate the immune system.
81
Antibodies
The proteins produced by the immune system.
82
When are antigenes produced?
A person’s immune system can recognise its own antigens, and thus will not produce antibodies for them. But, it will produce antibodies for non-self antigens.
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Type A
* Antigen A on RBCs
* Anti-B antibodies in plasma
* Donate to: A, AB
* Receive from: A, O
84
Type B
* Antigen B on RBCs
* Anti-A antibodies in plasma
* Donate to: B, AB
* Receive from: B, O
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Type AB
* Antigen A and antigen B on RBCs
* Neither anti-A nor anti-B antibodies in plasma
* Donate to: AB
* Receive from: A, B, AB, O
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Type O
* Neither antigen A nor antigen B on RBCs
* Both anti-A and anti-B antibodies in plasma
* Donate to: A, B, AB, O
* Receive from: O
87
# Describe:
Rhesus blood system (Rh +,-)
Rh antigens are **proteins**.
Rh antigens: Rh positive +
*Cannot produce anti-Rh antibody.*
No Rh antigens: Rh negative -
*Can produce an anti-Rh antibody that reacts against Rh antigens.*
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89
# Define:
Transfusion
The transfer of blood, or one of the components of blood, from one person to another.
90
Why is it important for blood types to be compatible in transfusions? (What happens if you mix incompatible types)
Mixing incompatible types causes agglutination: the clumping together of erythrocytes (red blood cells).
If the receiver’s blood contains, or is able to make, antibodies against the antigens on the donor’s red cells, the foreign cells will clump together and disintegrate.
91
Why must Rh blood groups be matched for transfusions?
The anti-Rh antibody is normally not present in the plasma of Rh-negative people, but it is introduced on exposure to the Rh-antigen.
*The first transfusion of Rh-positive blood to an Rh-negative person does not usually cause problems as antibodies are produced slowly.*
However, this first transfusion sensitises the person, so any subsequent exposure results in very rapid production of antibodies. — this results in the clumping of red blood cells.
92
Types of transfusions
| 6
1. Whole blood
2. Red cell concentrates
3. Platelet concentrates
4. Cryoprecipitate
5. Immunoglobulins
6. Autologous transfusion
93
# Define:
Whole blood transfusion
| And when it occurs
Blood as it is taken from the donor, but with a chemical added to prevent clotting. Mainly in cases of severe blood loss.
94
When are red cell concentrates used for transfusions?
Patients suffering from heart disease or severe anaemia.
95
When is plasma used for transfusions?
1. Patients requiring extra clotting factors for control of severe bleeding.
2. Patients with liver disease.
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How are red cell concentrates produced?
Spinning blood at a very high speed in a centrifuge.
Heavier cells sink to the bottom, leaving the lighter plasma on top.
The concentrate may or may not have platelets and white blood cells (leucocytes) removed.
97
When are platelet concentrates used for transfusions?
Patients who have abnormal platelets, or a reduced number of platelets.
98
How is cyroprecipitate produced?
*Freezing plasma and thawing it slowly.*
When the plasma is thawed, the cryoprecipitate remains solid.
It contains many of the substances necessary for blood clotting.
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100
When is cyroprecipitate used for transfusions?
1. Most often used for severe bleeding.
2. May be used to treat some forms of haemophilia.
101
# Define:
Immunoglobulin
A group of proteins that act as antibodies.
102
When are immunoglobulins used for transfusions?
1. Patients who are deficient in antibodies.
2. Particular immunoglobulins from certain donors are used to treat patients who have no immunity to a particular disease.
*E.g., tetanus immunoglobulin may be used to treat tetanus.*
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# Define:
Autologous transfusion
When the patients own blood is used.
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Benefits of autologous transfusions
It eliminates the risk of transmission of disease and most possible side effects of the usual transfusions.
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When is blood collected for autologous transfusion?
The blood is *collected from the patient prior* to an operation that may require a transfusion.
Blood is collected about *four weeks before the operation*.
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When are autologous transfusions used?
Often for elective surgeries.
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Lymphatic system purpose
To collect some of the fluid that escapes the blood capillaries and return it to the circulatory system.
It is also an important part of the body’s internal defence against disease-causing organisms.
108
Components of the lymphatic system
- A network of lymph capillaries joined to larger lymph vessels *(lymphatic vessels or lymphatics)*
- The network of lymph vessels joins to form two lymphatic ducts that empty the lymph into large veins in the upper chest.
- Lymph nodes, which are located along the length of some lymph vessels
- Lymph does not circulate — the lymphatic system is a one way system carrying fluid away from the tissues.
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Lymph
The excess fluid in the tissues that is returned to the blood by the lymphatic system.
110
Where are lymph vessels located?
The lymph vessels originate as blind-ended tubed in the spaces between the cells of most tissues.
111
Structure of lymph capillaries
Lymph capillaries are usually *slightly larger than blood capillaries.*
More permeable than most blood capillaries so that proteins and pathogens in the intercellular fluid can easily pass through the walls of the lymph capillaries into the lymph.
112
How is lymph moved through the lymphatic vessels?
The smooth muscle layer of the vessels is able to *contract to push the lymph along the vessel.*
The skeletal muscles surrounding the vessels also contract, providing additional force.
Larger lymph vessels have **valves** that close when the pressure drops, *preventing the backflow of lymph.*
*Why?*
*As there is no central pump, there is no force driving the direction of the flow of lymph.*
113
# Define:
Lymph node
114
Where are lymph nodes most numerous?
- Neck
- Armpits
- Groin
- Around the alimentary canal
115
What are lymph nodes surrounded by?
*Each is surrounded by a capsule of connective tissue that extends into the node, forming a framework.*
Within the framework are masses of lymphoid tissue, containing:
- lymphocytes
- macrophages
- plasma cells
*Spaces between the cells of the lymphoid tissue are criss-crossed by a network of fibres.*
116
Lymph nodes shape and size
Bean-shaped.
Range in length from 1mm to 25mm.
117
How does lymph move through nodes?
Lymph enters through vessels on the convex side of the node, filters through the spaces and passes out through vessels on the opposite side.
Lymph passes through *several nodes* before entering the *circulatory system*.
118
Lymphatic system's role in the immune system
**01. Larger particles, such as bacteria, are trapped ins the meshwork of *fibres* as the lymph flows through the spaces in the nodes.**
Large phagocytic cells called macrophages destroy these particles.
The macrophages ingest the particles by phagocytosis.
Projections from the macrophage surround the particle and take it into the cell, where it is destroyed by enzymes.
*Most bacteria ingested in this way are killed within 10-30 minutes.*
**02. When infections occur, the formation of lymphocytes increases, causing lymph nodes to become *swollen and sore*.**
