The circulatory system - blood (rbc, wbc, platelets and plasma)

Question 1

Structure of the red blood cells

Answer 1

• biconcave discs
• no nucleus
• contains haemoglobin

Question 2

Structure of white blood cells

Answer 2

• large cells containing a big nucleus

Question 3

Structure of platelets

Answer 3

• fragments of cells

Question 4

Structure of Plasma

Answer 4

• yellow liquid found in blood

Question 5

What is the role of plasma?

Answer 5

• yellow liquid which transports digested food, carbon dioxide, hormones, urea and heat energy

Question 6

Role of plasma - carbon dioxide

Answer 6

• carries away waste carbon dioxide from respiring cells to the lungs for exhalation

Question 7

Role of plasma - digested food

Answer 7

• caries digested food to cells for use in respiration or assimilation

Question 8

Role of plasma - hormones

Answer 8

• hormones produced by endocrine glands around the body are secreted into plasma to be carried to target organs

Question 9

Role of plasma - urea

Answer 9

• carried by the plasma to the kidneys for excretion in urine

Question 10

adaptations of red blood cells - haemoglobin

Answer 10

• contains a lot of haemoglobin so that the cell can carry a lot of oxygen

Question 11

adaptations of red blood cells - abscence of nucleus

Answer 11

• provides extra space for more haemoglobin, therefore more oxygen

Question 12

adaptations of red blood cells - biconcave

Answer 12

• increases surface area : volume ratio which increases rate of diffusion of oxygen

Question 13

What is the role of white blood cells?

Answer 13

white blood cells provide protection against pathogens (micro organisms which could cause infectious diseases)

Question 14

Role of phagocytes

Answer 14

• Phagocytes ingest pathogens
• they change shape producing pseudopodia which surrounds and engulfs the pathogens
• once inside, the cell releases enzymes to digest the pathogen

Question 15

Role of lymphocyte

Answer 15

• produce antibodies which are specific to (recognise and bind to) a single antigen type on the surface of a specific pathogen
• attachment of antibodies to the antigen triggers destruction of the pathogen, and can label them to be recognised and ingested by phagocytes

Question 16

What are vaccinations?

Answer 16

• injecting a dead or inactivated version of the pathogen
• even though the vaccine is harmless, it causes formation of memory cells
• memory cells are able to recognise when the patient is infected with harmful pathogens
• memory cells multiply and produce antibodies sooner, faster and in greater quantity

Question 17

How are platelets involved in blood clotting?

Answer 17

• when you have a cut, blood comes into contact with air which stimulates the platelets to release enzymes which trigger the conversion of fibrinogen into fibrin
• these fibrin molecules form a network over the cut, sealing it and forming a blood clot

Question 18

What do blood clots consist of?

Answer 18

• fibrin molecules and trapped red blood cells and platelets.