Health and Disease, Homeostasis, Proteins

Question 1

Define aetiology.

Answer 1

CAUSE of disease.

Question 2

Define pathogenesis.

Answer 2

HOW disease develops.

Question 3

Define symptoms.

Answer 3

WHAT patients feel.

Question 4

Define signs.

Answer 4

Doctor’s observations.

Question 5

Define diagnosis.

Answer 5

Determining nature of a disorder.

Question 6

Define prognosis.

Answer 6

Assessment of the future course and outcome of a patient’s disease.

Question 7

Define the six classifications of natural history.

Answer 7

Inflammation, circulatory disturbances, disorders of cell growth, degenerative disorders, development, unnatural.

Question 8

Explain the importance of maintaining constant internal environment.

Answer 8

As energy demand increases, supply must increase to meet demand and prevent disturbances. Failure to correct = illness, disease and pathology.

Question 9

Describe principles behind negative feedback control.

Answer 9

Restores internal environment,

Question 10

Explain what is meant by a feed-forward control.

Answer 10

More sophisticated, anticipates change, common in pathophysiology.

Question 11

What is the daily water balance in man?

Answer 11

2550mls (gains and losses match). input regulated by thirst and output regulated by urinary loss.

Question 12

Identify the three different body fluid compartments.

Answer 12

1. Plasma (ECF)
2. Interstitial fluid (ECF)
3. Intracellular fluid (ICF)

Question 13

What proportion of total body water is found in the ECF?

Answer 13

1/3

Question 14

What proportion of total body water is found in the ICF?

Answer 14

2/3

Question 15

What is the volume of total body water?

Answer 15

42L

Question 16

Describe the nature of the capillary wall and it’s location.

Answer 16

Permeable to everything BUT plasma proteins - found between plasma and interstitial fluid.

Question 17

Describe the nature of the cell membrane and it’s location.

Answer 17

Selective permeability - found between interstitial fluid and intracellular fluid.

Question 18

Define the dilution principle.

Answer 18

Measures body fluid volume (v=m/c)

Question 19

What substance can be sampled directly?

Answer 19

Plasma. Therefore only ECF, plasma and total body water can be measured directly.

Question 20

How do you measure ICF?

Answer 20

INDIRECTLY (ICF = TBW - ECF)

Question 21

What is used to sample plasma?

Answer 21

Dyes/Labels

Question 22

What is used to sample ECF?

Answer 22

Sucrose and insulin

Question 23

What is used to sample TBW?

Answer 23

Loading dose of heavy water.

Question 24

150mg sucrose was injected into plasma of 70kg man. The concentration of sucrose in the blood sample after distribution was 0.01mg/ml. 10mg were excreted or metabolised. What is the volume of ECF?

Answer 24

(150mg-10mg)/0.01mg/ml = 14000ml (14L)

Question 25

Where is the largest concentration of potassium ions found?

Answer 25

In the ICF.

Question 26

Where is the largest concentration of sodium ions found?

Answer 26

In the ECF.

Question 27

Where is the largest concentration of chloride ions found?

Answer 27

In the ECF.

Question 28

Where is the largest concentration of protein found?

Answer 28

In the ICF.

Question 29

How many classes of naturally occurring amino acids exist?

Answer 29

7

Question 30

Describe the 7 classes of amino acids.

Answer 30

1. Aliphatic (linear side chain)
2. Aromatic (stable ring)
3. Acidic (negatively charged)
4. Basic (positively charged)
5. Sulphur containing (e.g cysteine)
6. Uncharged polar (hydrophilic)
7. Other (proline)

Question 31

What are the three main structures of proteins and their associated functions?

Answer 31

1. Fibrous (elongated strand-like) - structural (bone matrices, tendons, muscle fibre)
2. Globular (spherical) - varied function (enzymes, transporters)
3. Membranous - cell or organelle membrane (relays signals, membrane transporters)

Question 32

Define primary structure.

Answer 32

Sequence of AAs in a polypeptide chain, joined by peptide bonds from condensation reaction.

Question 33

Define secondary structure.

Answer 33

Spatial arrangement of AA residues that are near each other in a linear sequence (alpha-helices or beta-sheets)

Question 34

Define tertiary structure.

Answer 34

Spatial arrangement of AA residues that are far apart with a linear sequence held together by forces.

Question 35

List examples of forces present in the tertiary structure of proteins

Answer 35

Disulphide bonds, Van de Waals, Ionic Interactions, Hydrophobic Interactions, Hydrogen bonds

Question 36

Define quaternary structure.

Answer 36

Spatial arrangement of individual polypeptide chains in a multi-subunit protein.

Question 37

Describe the structure and function of haemoglobin.

Answer 37

Quarternary structure with 4 sub-units and Fe in centre for oxygen transport, co-operative binding exists.

Question 38

What will happen to RBCs if they are placed in a solution of 30mM urea and 170mM NaCl.

Answer 38

They will shrink

Question 39

Can urea freely cross the cell membrane?

Answer 39

Yes. It is a penetrating solute and therefore equilibrate across the cell membrane and cause no osmotic effect.

Question 40

What tissue has the lowest water content?

Answer 40

Fat

Question 41

What tissue has the highest water content?

Answer 41

Muscle

Question 42

Can glucose freely cross the cell membrane?

Answer 42

No. It requires carrier mediated transport proteins.

Question 43

What type of molecules can dissolve through the phospholipid bilayer?

Answer 43

Non-polar (lipophilic) molecules

NOT polar hydrophobic molecules.

Question 44

How does NaCl increase blood pressure?

Answer 44

NaCl increases plasma Na+ concentration hence drawing more water into the plasma by osmosis and thus increasing blood pressure. (NOTE: since K+ is confined to the intracellular space, ingested KCl would not have the same effect.)