Blood and haemostasis

Question 1

State the functions of the blood

Answer 1

Transports heat around the body
Supplies oxygenated blood to respiring tissues
Transports carbon dioxide from tissues to the lungs
Transports hormones to target organs
Nutrients from digestion transported in the blood
Delivery of waste to excretory organs
Regulates osmotic pressure
Carries WBC and platelets involved in tissue repair and inflammation

Question 2

Describe the composition of blood

Answer 2

Blood is a connective tissue, plasma makes up 55% of blood, 45% RBC, platelets and WBC

Question 3

What is the concentration of RBC in males and females?

Answer 3

Males: 42-52%
Females:37-47%

Question 4

What is Polycythaemia?

Answer 4

The thickening of the blood caused by overproduction of RBC from bone marrow, a form of blood cancer

Question 5

What is anaemia?

Answer 5

Lack of functioning RBC, leads to less O2 carried in the blood,

Question 6

Colour of blood in humans & most vertebrates?

Answer 6

RED, bright red in arterial blood and a darker colour in venous blood, as Hb contains Fe prosthetic group giving colouration

Question 7

Colour of blood in crustaceans, squid & octopi?

Answer 7

Blue, as it contains hemocyanin which floats freely in the blood, has Cu prosthetic group, oxygenated it is blue, deoxygenated it is colourless

Question 8

Colour of blood in worms & leeches?

Answer 8

Green as they contain chlorocruorin, which is light green when deoxygenated and a deeper green when oxygenated, some species contain Hb

Question 9

Colour of blood in penis worms, peanut worms & brachiopods

Answer 9

Purple, it contains hemerythrin, which is less efficient than Hb, colorless when deoxygenated and lilac when oxygenated

Question 10

Describe the components in blood plasma?

Answer 10

Makes up 55% of blood. 90% is made of water, 10% dissolved ions, proteins etc,
pH of 7.4, transports heat, nutrients or waste where they need to be
Plasma produces fibrinogen involved in blood clotting
Carries antibodies, albumin involved in osmotic pressure
7% is made in liver, drop in plasma proteins is detected by liver, liver produces more

Question 11

Describe the structure & function of RBC

Answer 11

Known as erythrocytes, small, biconcaves giving a large SA:vol, allow rapid diffusion. Flexible enabling it to squeeze through gaps in capillaries
Has 4 Fe groups per Hb
Has 250-280 million Hb molecules per RBC
No nucleus, mitochondria or ER, so more space for Hb, the short life span of 120 days, broken down in the liver, made in bone marrow, respires anaerobically

Question 12

Define isotonic state of RBC

Answer 12

Where the concentration of water is equal both in & outside of cell, RBC is normal shape & size

Question 13

Define hypotonic state of RBC

Answer 13

RBC swells as the concentration of water is greater outside of the cell, causing water to move in via osmosis, causing swelling, could lead to bursting of cell

Question 14

Define Hypertonic state of RBC

Answer 14

Where concentration of water is greater inside the cell, so water moves out of the RBC, leaving it to become crenated, reduces SA, cytoskeleton sticks out giving spikey appearance

Question 15

Describe role of WBC

Answer 15

Involved in fighting infection and the immune response
5 types of WBC, can be divided into 2 groups agranulocytes (normal nucleus & agranular cytoplasm) and granulocytes (multi-lobed nucleus & granular cytoplasm)

Question 16

Describe the role of the 5 WBC

Answer 16

Neutrophils- involved in phagocytosis
Eosinophils- involved in allergies and killing of parasites
Basophils- (mast cells), involved in inflammation response, release cytokines & histamines
Lymphocytes-produce antibodies
Monocytes/macrophages- involved in phagocytosis

Question 17

Function of platelets

Answer 17

Also known as thrombocytes, they are fragments of cells involved in blood clotting reaction (haemostasis) damage to blood vessels occurs & platelet plug is formed
soluble fibrinogen converted to insoluble fibrin via thrombin enzyme activation

Question 18

What is erythropoiesis

Answer 18

The process that makes RBC

Question 19

Why is erythropoiesis needed?

Answer 19

RBC have a lifespan of 120 days due to normal organelles, so they need replacing, they are broken down by liver and release bilirubin which is transported to kidneys to be excreted.
RBC needs to stay within a homeostatic range
to prevent anaemia or Polycythaemia

Question 20

Function of Erythropoietin

Answer 20

A vital hormone needed for the production of RBC, this stimulates RBC production, a base range also circulates in the blood
Chemoreceptors in the kidney detect hypoxia, more EPO is secreted red bone marrow to produce RBC (negative feedback)

Question 21

Stages of erythropoiesis

Answer 21

1. it begins with a haemopoietic stem cell which specialises into a hemocytoblast, these are found in the bone marrow and can be stimulated to circle the blood
2. Common myeloid progenitor cells are produced which produce RBC, mast cells, myeloblasts etc
3. The myleiod cells mature into normoblasts, they then mature further and lose their nucleus to form reticulocytes, this creates biconcave shape
4. reticulocytes are immature RBC’s, they mature further and lose further organelles e.g., ribosomes, to form erythrocytes which are fully mature RBC
   From a stem cell to a reticulocyte is takes 15 days, they mature into RBC within 2 days

Question 22

Describe Haemostasis

Answer 22

This is the blood clotting mechanism, that occurs when a blood vessel becomes damaged and blood is lost from it, known as a haemorrhage
it consists of 3 stages: vascular spasm, Plug formation and coagulation

Question 23

Explain vascular spasm (stage 1 in haemostasis)

Answer 23

Involves vasoconstriction, to reduce blood flow to damaged vessel via constriction of smooth muscle, this limits volume of blood lost and buys time for further steps

Question 24

Explain plug formation
(stage 2 in haemostasis)

Answer 24

Platelets clump together to seal the hole in the vessel, hormones stimulate cells to become sticky and adhesive, allows sticking to the vessel wall, as they clump this creates a positive feedback mechanism. stimulating more chemicals to be released causing more platelets to clump

Question 25

Explain coagulation
(stage 3 in haemostasis)

Answer 25

Coagulation contains 3 phases, end of P1 ends with the activation of the thrombin enzyme, responsible for converting fibrinogen to fibrin

This platelet plug is formed and fibrin fibres interlock through plug. This further binds platelets together, creating a mesh to seal the wound. As platelets are used up serum is produced

Question 26

Describe the importance of vitamin K in haemostasis

Answer 26

It is a cofactor involved in blood clotting, needed to produce proteins and clotting factors, without vitamin K coagulation would not be effective.
Vitamin K can also prevent osteoporosis, heart diseases,
Found in kale and dark leafy greens

Question 27

Describe the importance of calcium in haemostasis

Answer 27

Calcium is needed for the activation of platelets, as well as activating thrombin enzyme, calcium also activates factor XVIII which strengthens fibrin mesh, vital for coagulation