Health and Disease, Homeostasis, Proteins Flashcards
Define aetiology.
CAUSE of disease.
Define pathogenesis.
HOW disease develops.
Define symptoms.
WHAT patients feel.
Define signs.
Doctor’s observations.
Define diagnosis.
Determining nature of a disorder.
Define prognosis.
Assessment of the future course and outcome of a patient’s disease.
Define the six classifications of natural history.
Inflammation, circulatory disturbances, disorders of cell growth, degenerative disorders, development, unnatural.
Explain the importance of maintaining constant internal environment.
As energy demand increases, supply must increase to meet demand and prevent disturbances. Failure to correct = illness, disease and pathology.
Describe principles behind negative feedback control.
Restores internal environment,
Explain what is meant by a feed-forward control.
More sophisticated, anticipates change, common in pathophysiology.
What is the daily water balance in man?
2550mls (gains and losses match). input regulated by thirst and output regulated by urinary loss.
Identify the three different body fluid compartments.
- Plasma (ECF)
- Interstitial fluid (ECF)
- Intracellular fluid (ICF)
What proportion of total body water is found in the ECF?
1/3
What proportion of total body water is found in the ICF?
2/3
What is the volume of total body water?
42L
Describe the nature of the capillary wall and it’s location.
Permeable to everything BUT plasma proteins - found between plasma and interstitial fluid.
Describe the nature of the cell membrane and it’s location.
Selective permeability - found between interstitial fluid and intracellular fluid.
Define the dilution principle.
Measures body fluid volume (v=m/c)
What substance can be sampled directly?
Plasma. Therefore only ECF, plasma and total body water can be measured directly.
How do you measure ICF?
INDIRECTLY (ICF = TBW - ECF)
What is used to sample plasma?
Dyes/Labels
What is used to sample ECF?
Sucrose and insulin
What is used to sample TBW?
Loading dose of heavy water.
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?
(150mg-10mg)/0.01mg/ml = 14000ml (14L)
Where is the largest concentration of potassium ions found?
In the ICF.
Where is the largest concentration of sodium ions found?
In the ECF.
Where is the largest concentration of chloride ions found?
In the ECF.
Where is the largest concentration of protein found?
In the ICF.
How many classes of naturally occurring amino acids exist?
7
Describe the 7 classes of amino acids.
- Aliphatic (linear side chain)
- Aromatic (stable ring)
- Acidic (negatively charged)
- Basic (positively charged)
- Sulphur containing (e.g cysteine)
- Uncharged polar (hydrophilic)
- Other (proline)
What are the three main structures of proteins and their associated functions?
- Fibrous (elongated strand-like) - structural (bone matrices, tendons, muscle fibre)
- Globular (spherical) - varied function (enzymes, transporters)
- Membranous - cell or organelle membrane (relays signals, membrane transporters)
Define primary structure.
Sequence of AAs in a polypeptide chain, joined by peptide bonds from condensation reaction.
Define secondary structure.
Spatial arrangement of AA residues that are near each other in a linear sequence (alpha-helices or beta-sheets)
Define tertiary structure.
Spatial arrangement of AA residues that are far apart with a linear sequence held together by forces.
List examples of forces present in the tertiary structure of proteins
Disulphide bonds, Van de Waals, Ionic Interactions, Hydrophobic Interactions, Hydrogen bonds
Define quaternary structure.
Spatial arrangement of individual polypeptide chains in a multi-subunit protein.
Describe the structure and function of haemoglobin.
Quarternary structure with 4 sub-units and Fe in centre for oxygen transport, co-operative binding exists.
What will happen to RBCs if they are placed in a solution of 30mM urea and 170mM NaCl.
They will shrink
Can urea freely cross the cell membrane?
Yes. It is a penetrating solute and therefore equilibrate across the cell membrane and cause no osmotic effect.
What tissue has the lowest water content?
Fat
What tissue has the highest water content?
Muscle
Can glucose freely cross the cell membrane?
No. It requires carrier mediated transport proteins.
What type of molecules can dissolve through the phospholipid bilayer?
Non-polar (lipophilic) molecules
NOT polar hydrophobic molecules.
How does NaCl increase blood pressure?
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.)
