Unit 2 - Topic 14 - The Circulatory System Flashcards
Give three functions of the circulatory system
Transport of blood cells, food (glucose/amino acids), carbon dioxide and urea
Protection against disease
Thermoregulation
What is the function of a red blood cell?
The function of these cells is to carry oxygen around the body
What substance in the red blood cell allows them to carry oxygen?
Haemoglobin (rich in iron) enables the red blood cells to carry oxygen. The oxygen binds with the haemoglobin to form oxyhaemoglobin.
How is the red blood cell adapted for its function?
Biconcave shape allows for a greater surface area for diffusion to occur
No nucleus, more space for oxygen
Once cell thick, short diffusion distance
Name two types of white blood cell
Phagocytes
Lymphocytes
What is the function of white blood cells?
They are important in the defence against disease
Describe how a lymphocyte aids in the detection of a foreign pathogen
Lymphocytes produce antibodies which are micro-organism specific. Certain antibodies will only work on certain pathogens. The antibodies produced will attach onto the protein structures called antigens present on a microbe and will identify the organism as foreign. Antibodies can link to more than one pathogen and cluster them together.
Describe how a phagocyte digests invading pathogens and name what this process is called.
After the pathogen has been identified by the lymphocyte, the phagocyte will begin to engulf the foreign microbe. The phagocyte will internally secrete enzymes which will digest the micro-organism, rendering it inactive. This process is known as phagocytosis.
What is the function of platelets.
These very small structures are important in blood clotting and the formation of scabs
How do the platelets carry out their role in the event of an open wound or incision?
The platelets rupture, setting off many reactions. The end result of these cause the fibrinogen (soluble) which is present in the plasma to convert to fibrin. This fibrin forms a ‘mesh network’ and traps other blood components such as red blood cells and white blood cells.
What is the function of the plasma in the blood?
The plasma is responsible for the transport of blood components and other substances.
What does the plasma transport?
The plasma transports blood components (such as red blood cells, platelets, white blood cells). The plasma is the liquid part of the blood and so carries many waste products (carbon dioxide, water, urea). The plasma is also responsible for the transport of absorbed food molecules such as glucose and amino acids, and in the movement of hormones. The plasma also contains the protein fibrinogen which is important for blood clotting.
How does the plasma stop cell lysis and crenation?
Salt and other chemicals in the plasma keep its concentration stable and at a concentration similar to the blood cells (isotonic solution). This prevents cell lysis or crenation from occurring .
Name the three types of blood vessels
Arteries
Veins
Capillaries
To alleviate the high pressure present in the arteries after leaving the heart, they branch out into smaller vessels which eventually form a network of capillaries. What is the name of these vessels?
Arterioles
When the capillary vessels have exchanged substances with the body cells and are ready to return to the heart, they converge into larger vessels which eventually form veins containing deoxygenated blood. What is the name of these vessels?
Veinules
For each of the three main blood vessel types, state the direction of blood flow relative to the heart, the thickness of their wall and the blood pressure for each vessel.
Artery
- Away from heart
- Thick
- High
Vein
- Back to heart
- Relatively thin
- Low
Capillary
- Links arteries and veins
- Thin (one cell thick)
- Low
Arteries carry oxygenated blood and veins carry deoxygenated blood. Give two examples of exceptions to this rule.
The pulmonary artery
The pulmonary vein
Describe the structure of an artery
Narrow lumen Endothelium lining Muscle layer Elastic fibre layer Thick wall
Describe the structure of a vein
Wide lumen Endothelium lining Relatively thin Muscle layer Relatively thin Elastic fibre layer Relatively thin wall Valves
Describe the structure of a capillary
Endothelium lining
Thin
One cell thick
Permeable
What is the role of the pulmonary vein?
Carry oxygenated blood from the lungs to the heart
What is the role of the Aorta?
Carries oxygenated blood from the heart to the body
What is the role of the vena cava?
Carries deoxygenated blood from the body to the heart