Body Systems L8

Question 1

Describe the characteristics of blood & average figures in regards to adult human.

Answer 1

•	Blood:
	Transport -> inorganic & organic molecules, formed elements & heat. 
-	Component of cardiovascular system 
-	Fluid connective tissue 
-	Avg. adult -> 5litres
-	7% body weight

Question 2

Describe the composition of the blood

Answer 2

•	Composition of blood:
-	Plasma: 55%
Water -> 92%
Plasma proteins -> 7%
    -->Albumin, Globulin, Fibrinogen, regulatory proteins
Other solutes -> 1%
    -->Electrolytes, organic nutrients, waste.
-	Red Blood Cells: 45%
-	White Blood cells: <1%
-	Platelets: <1%

Question 3

What are the functions of the blood.

Answer 3

•	Function of blood:
-	Transport:
Gases -> O2 & CO2
Nutrients
Excretory products 
Temperature
-	Defense:
Antibodies -> white blood cells 
Clotting factors

Question 4

Name the process responsible for formation of red blood cells

Answer 4

Haematopoiesis/

Haemopoiesis:

Question 5

Describe Haematopoiesis?

Answer 5

• Haematopoiesis/Haemopoiesis:
 Process -> formation -> blood cells
 All cells produced -> 1 haematopoietic stem cell
Self-renewing
Differentiates -> different cells -> depending on requirements of body
i) Common myeloid progenitor -> production -> all cells except lymphocytes
ii) Common lymphoid progenitor -> production -> lymphocytes

Question 6

Describe the differentiation of the original haematopoietic stem cell.

Answer 6

 All cells produced -> 1 haematopoietic stem cell
Self-renewing
Differentiates -> different cells -> depending on requirements of body
i) Common myeloid progenitor -> production -> all cells except lymphocytes
ii) Common lymphoid progenitor -> production -> lymphocytes

Question 7

Name the process responsible for production of erythropocytes/RBCs

Answer 7

• Erythropoiesis:

Question 8

What is erythropoiesis?

Answer 8

• Erythropoiesis:

 Production of erythrocyte (RBCs)

Question 9

What are the requirements of erythropoiesis?

Answer 9

Requires:

• Enthyropoietin (EPO) -> hormone
• > Initiates erythropoiesis
• Iron
• Vitamin B12 & folic acid (B9)
• Intrinsic factor
• Amino acids

Question 10

Describe the locations of erythropoiesis

Answer 10

• Foetus ->Early in yolk sac, then liver & spleen
  ->Later -> bone marrow
• Infant -> All bone marrow
• Adult -> Red bone marrow only
  –>Ribs, vertebrae, skull, upper ends -> long bones.
  >Can digress & erythropoiesis occur in all parts of adult body when necessary.

Question 11

Describe production of erythrocytes

Answer 11

 Production of RBCs required
 Triggers kidneys -> release erythropoietin hormone
 Erythropoietin -> acts on stem cells
 Instigates specialisation of stem cell -> production -> RBCs
 Proerythroblast -> immature cell -> bone marrow
Matures -> Erythroblast
 Normoblast -> containing full haemoglobin conc.
–>Constant production of haemoglobin during these stages
 Normoblast ejects nucleus -> reticulocyte
Reticulocyte still contains some ribosomal RNA
>If Reticulocyte released -> circulation prematurely -> still some ability to
produce haemoglobin.
Small number in circulation -> later mature -> RBCs
Lots of reticulocytes
->Anaemia
 Erythrocyte (RBC)

Question 12

Why do reticulocytes contain ribosomal RNA>

Answer 12

> If Reticulocyte released -> circulation prematurely -> still some ability to
produce haemoglobin.

Question 13

What could be the reason for lots of reticulocytes in circulation system?

Answer 13

->Anaemia

Question 14

Describe the structure & characteristics of RBCs

Answer 14

•	Structure of RBCs:
-	Biconcave disc 
Enables easy passage through vessels 
-	7-8 micrometeres -> diameter
-	Foldable & flexible -> deforms easily 
-	Stable
-	No organelles 
more room for haemoglobin 
-	Function:
Transportation -> oxygen & CO2
-	Life span 
 120 days 
    > Broken down & recycled.

Question 15

Describe how RBCs are broken down & recycled & why this occurs

Answer 15

• Breakdown & recycling of RBCs:
 Weakening -> cell membrane
No nucleus -> repair damage
 Broken down -> macrophages -> spleen
Heme
->Transported -> Billirubin -> Liver
>Secreted -> bile -> excreted form body.
Iron
->Transported -> Transferrin -> back into circulation
> stored -> Ferritin protein -> liver, spleen
&raquo_space;Reused -> production of RBCs.

Question 16

Describe erythrocyte homeostasis

Answer 16

• Erythrocyte Homeostasis:
 Low conc O2
 Detected by kidneys -> stimulates incr. production -> erythropoietin
 Detected -> stem cells -> incr. production of RBCs
 More RBCs -> higher O2 transportation capacity -> incr. O2 conc.

Question 17

What are potential causes of hypoxia?

Answer 17

 Causes of hypoxia (low O2 conc)

• Incr. excersise
• High altitude
• Smoking
• Bleeding

Question 18

Describe the characteristics of haemoglobin

Answer 18

•	Haemoglobin:
	Transports O2  & CO2
	Synthesis begins -> proerythroblast
65% -> erythroblast
35% -> reticulocyte
	280 million per RBC
	15g/dl 
	4 subunits:
2 alpha & 2 beta
Each contains haem 
     >Bound -> globin -> long polypeptide chain
Ferrous iron atom Fe2+ at centre of each subunit
     >>Can reversibly bind -> O2

Question 19

Describe the structure of each subunit in haemoglobin

Answer 19

 4 subunits:
2 alpha & 2 beta
Each contains haem
>Bound -> globin -> long polypeptide chain
Ferrous iron atom Fe2+ at centre of each subunit
&raquo_space;Can reversibly bind -> O2

Question 20

What is anaemia and what are the values in which it occurs?

Answer 20

• Conc. of haemoglobin -> blood -> below accepted normal range
   Less than 13.5g/l -> men
   Less than 12.0g/l -> women

Question 21

What are the causes of anaemia

Answer 21

-	Causes:
Decreased production -> RBC 
Incr. destruction -> RBC
Blood loss
-	Not a diagnosis -> seek cause

Question 22

Name the types of anaemia

Answer 22

	Iron deficiency anaemia:
	Megaloblastic anaemia:
	->Vitamin B12 deficiency 
        ->Folic acid/Folate deficiency
       Sickle cell anaemia:
	Thalassaemias:

Question 23

Describe iron deficiency anaemia

Answer 23

	Iron deficiency anaemia:
	Most common 
	Hypochromic (paler), microcytic (smaller) RBCs
	Decr. mean cell volume (MCV)
Causes:
-	Pregnancy 
-	Malnutrition
-	Malabsorption
-	Bleeding -> GI tract (ulcer, malignancy)
-	Menorrhagia

Question 24

Describe & name the 2 types of Megaloblastic anaemia:

Answer 24

	Vitamin B12 deficiency 
Require intrinsic facor (IF) -> secreted -> stomach -> vitamin b12 absorption
Abnormal RBC
Macrocytic (incr. MCV)
Causes:
Lack -> IF -> Pernicious anaemia
Crohns, coeliac disease (absorption)
Treatment:
Sufficient IF & low B12 -> Dietary supplements 
Low level IF -> must bypass gut -> Vitamin B12 injections
	Folic acid/Folate deficiency
Similar characteristics -> Vitamin B12 def. 
Causes:
-	Pregnancy 
-	Old age 
-	Dietary deficiency

Question 25

Describe sickle cell anaemia

Answer 25

 Sickle cell anaemia:

• Hereditary: African, West Indian
• Abnormal haemoglobin structure
• Sickle-shaped cells -> stuck in vessels -> decr. O2 transportation
• High in malarial countries -> provides resistance
• No cure

Question 26

Describe Thalassaemias

Answer 26

• Herediatry: Mediterranean, Middle/Far Eastern
• Abnormal haemoglobin production
  Alpha & beta thalassaemias

Question 27

Describe the transportation of Oxygen in molluscs & arthropods & it’s characteristics

Answer 27

• Molluscs & arthropods -> harmocyanin -> transportation O2
–>Instead -> Fe2+
Blue-green when oxygenated
Suspended -> haemolymph -> (Not RBCs)
–>Not confined to circulatory system -> directly bathes cells.