Intro to structure + function of blood

Question 1

What is the structure of blood?

Answer 1

• CELLS ; red, white, platelets
• PLASMA (fluid)

Question 2

What are the (3) functions of blood?

Answer 2

• Transport
• Defence
• Homeostasis

Question 3

What does blood look like after centrifuging?

Answer 3

• Plasma at top (fluid)
• Buffy coat in middle (white cells + platelets)
• Red cells at the bottom
  *

Question 4

What are red blood cells?

Answer 4

• Erythrocytes
• Biconcave discs
• No nucleus + do not contain DNA, RNA or mitochondria

Question 5

What is the colour of white blood cells (AKA leukocytes)?

Answer 5

Colourless

Question 6

What are the two commonest types of WBCs?

Answer 6

• Neutrophils
• Lymphocytes

Question 7

Describe characteristics of neutrophils

Answer 7

• Polymorphonuclear: irregular, multi-lobed nucleus
• Granulocyte cell: prominent cytoplasmic ganules

Question 8

What are the other two types of granulocytes apart from neutrophils and what do they stain?

Answer 8

• Eosinophil - stain red with eosin
• Basophil - stain blue with basic dyes

Neutrophil is the most common WBC, whereas eosinophils make up 1-4% of WBCs and basophils <0.5%.

Question 9

What are mononuclear cells? Give examples

Answer 9

• Lack granules
• Large, regular nuclei
• Two types: monocytes + lymphocytes

Question 10

What are platelets?

Answer 10

• Thrombocytes
• Cytoplasmic fragments
• No nucleus
• Membrane bound
• Contain granules

Question 11

Where do blood cells come from?

Answer 11

• Mature blood cells produced from stem cells in bone marrow
• Bone marrow contains many immature cells
• Some blood diseases can be treated by bone marrow transplant

Question 12

What does plasma generally contain?

Answer 12

• Water
• Salts
• Proteins
• Metabolites
• Carbohydrates
• Lipids

Question 13

Which positive ions (cations) are present in plasma?

Answer 13

• Sodium
• Potassium
• Calcium
• Magnesium
• Hydrogen

Question 14

Which negative ions (anions) are present in plasma?

Answer 14

• Chloride
• Bicabonate
• Phopshate
• Sulphate
• Organic anions

Question 15

What is the difference between plasma and serum?

Answer 15

• Plasma is the fluid component of whole blood
• Serum is the fluid left after blood clotting
• Some blood tests require unclotted blood/plasma (use anticoagulant)
• Other tests work better with serum than plasma

Question 16

What are the 4 major classes of serum proteins?

Answer 16

• Albumin
• Alpha globulins
• Beta globulins
• Gamma globulins

Question 17

What is albumin?

Answer 17

• Single protein made in the liver
• >90%
• Maintaining plasma oncotic pressure (colloid osmotic pressure)
• Transport for substances w/ low water solubility
• General purpose carrier

Question 18

What are alpha and beta globulins?

Answer 18

• Variety of proteins made in liver
• 1-4% of plasma proteins
• For transport + defence

Question 19

What are gamma globulins?

Answer 19

• Produced by B-lymphocytes
• <0.5% of plasma proteins
• Immunoglobulins eg. IgA, IgG
• Antibodies which have a role in body’s defence against infection

Question 20

What is fibrinogen?

Answer 20

• 2-5% of plasma protein
• Blood clotting

Question 21

What does blood transport?

Answer 21

• Carry oxygen (from lungs) / nutrients to tissues
• Remove CO₂ / other waste from tissues
• Transport other substances (eg hormones) from sites of prod to site of action

Question 22

How is CO₂ removed from body tissues? Where does it go?

Answer 22

• Goes to lungs from tissues
• Some CO₂ carried by RBCs
• But most CO₂ carried as bicarbonate in plasma
• Red cell enzyme carbonic anhydrase helps CO₂ to dissolve

Question 23

The major constituent of erythrocytes is haemoglobin. What is the structure of this and how does it carry oxygen?

Answer 23

• Haemoglobin is a tetramer of 4 polypeptide chains:
  
  • 2 alpha globin chains
  • 2 beta globin chains
• Each globin chain carries a haem as a prosthetic group
• The haem holds a ferrous (Fe²⁺) iron atom
• Oxygen binds reversibly to the iron atom by coordination bond
• 300,000,000 Hb molecules in each RBC

Question 24

What do oxyhaemoglobin and deoxyhaemoglobin look like?

Answer 24

• Oxy = fully saturated with O₂ = bright red
• Deoxy = lost all O₂ = blue-purple

Question 25

What is pulse oximetry?

Answer 25

* Measures colour of haemoglobin * Determines if patient is hypoxic

Question 26

What substances can plasma proteins carry?

Answer 26

* **Poorly soluble** in water - eg. lipids, lipid-soluble hormones + vitamins * **Metal** ions - eg. Ca²⁺, Fe²⁺, Cu²⁺

Question 27

In regards to white blood cells, what do neutrophils do?

Answer 27

* Phagocytose + kill bacteria and fungi * Main mediators of **innate** immunity

Question 28

What do lymphocytes do?

Answer 28

* Main mediators of **adaptive** (acquired) immunity * Produce **antibodies** * Kill **virus** infected cells

Question 29

What do eosinophils and basophils do?

Answer 29

* Eosinophils and basophils both kill parasites and are involved in allergic responses Basophils (mast cells) are also involved in inflammation!

Question 30

What do monocytes/macrophages do?

Answer 30

Phagocytosis of dead cells + pathogens

Question 31

What are immunoglobulins?

Answer 31

* Gamma globulins * Made by B-lymphocytes * Act as antibodies against pathogens

Question 32

What are complement proteins?

Answer 32

* Kill bacteria + other pathogens * Cooperate with Ig + WBC

Question 33

How do platelets stop bleeding?

Answer 33

* Major role = primary haemostasis * Recognise damage at blood vessel wall * Form a platelet plug * Prevent/stop bleeding * But it is insecure + temporary

Question 34

How does plasma protein fibrinogen contribute to haemostasis?

Answer 34

* Fibrinogen is a major plasma protein * Converted to **fibrin**, forms **blood clot** * Clotting factors control process * Fibrin clot reinforces primary platelet plug

Question 35

Homeostasis is keeping the internal environment of the body constant. Give examples of the blood's role of homeostasis

Answer 35

* Maintaining pH (7.4) * Controlling distribution of water + solutes * Distributing heat

Question 36

What is the total blood *and* plasma volume "for a 70kg male"?

Answer 36

* TBV = 5 litres * Plasma volume = 2.5-3 litres

Question 37

What is haematocrit and the normal value for it?

Answer 37

* Ht (haematocrit) AKA packed cell volume (PVC) * HT = vol of cells / total volume * Normal value: ~0.4 - 0.5

Question 38

What is the average life span of a red blood cell?

Answer 38

120 days

Question 39

What tests does a **full blood count** (FBC) include?

Answer 39

* **Haemoglobin** concentration (Hb in g/l) * Mean **(red)** **cell volume** (MCV) * **White blood cell count** (WBC) * **Haematocrit** (Ht/Hc) * **Liver functon tests** (LFTs) * **Urea + electrolytes** (U + E) * Blood **glucose**

Question 40

From the full blood count, which counts are important for dignosing anaemia in comparison to infection?

Answer 40

_FOR ANAEMIA:_ * Hb conc * MCV * Ht _FOR INFECTION:_ * WBC * Neutrophil count * Lymphocyte count

Question 41

What do LFTs test/look for?

Answer 41

* Albumin concentration * Liver enzymes (released from damaged liver cells) * Clotting factors

Question 42

Why are urea and electrolyte tests important?

Answer 42

* In diagnosing kidney function * Also detect metabolic abnormalities