Flashcards in WEEK 3 Deck (54):
What are the range of functions proteins perform? Give examples alongside. (HINT: there's 5)
1. STRUCTURE: Collagen = the protein of bone, skin & tendon. The main component of connective tissue & makes up 25-35% of our total protein
2. TRANSPORT: Hb, found in erythrocytes, carries & delivers oxygen to metabolic tissues. Composed of 4 protein subunits, each of which contains a Haem group
LDL & LDL receptors transport cholesterol molecules & coordinates uptake into cells
3. DEFENCE: Ab = defence against INFECTION. Made from light & heavy polypeptide chains covalently linked by disulphide bonds
4. REGULATION: Lac repressor helps to control gene expression
5. CATALYSTS: Enzymes = regulation of ALL biological systems. E.g. Lysozyme catalyses cutting of polysaccharide chains
If the shape of a protein is changed, what is also affected?
What is the primary structure of a protein?
The sequence of amino acids it is made up from
Give an example of each of the following; (i) non-polar aliphatic (ii) non polar aromatic (iii) polar uncharged (iv) polar -vely charged (v) polar +vely charged (vi) sulphur containing (vii) Imino.
(iv) Aspartic acid
What are polypeptides?
polymers of AA monomers linked by peptide bonds (covalent bond formed between carboxyl & amino group)
Define (i) Amino acid residue (ii) Prosthetic group (iii) N-terminal end (iv) C-terminal end.
(i) what is left of an AA when 2 or more are combined & water is removed
(ii) a non-AA substance that's strongly bound to a protein & necessary for the protein part of an enzyme to function
(iii) has a free amine group, is the start of the polypeptide sequence
(iv) has a free carboxyl group
What is an acid? What is a base?
An acid is a molecule that tends to release a hydrogen ion
A base is any molecule that readily combines with a hydrogen ion
What is the equations for the equilibrium constant & the henderson-hasselbach equation?
Ka = [H+][A-] / [HA]
pH = pKa + log[A-] / [HA]
What is the pKa?
The pH at which HALF the molecules are disassociated
What is the secondary structure of a protein? What are they stabilised by?
The initial folding pattern of a linear polypeptide
Stabilised by hydrogen bonds
What are the 3 main types of secondary structure? Describe them.
1. ALPHA HELIX - formed when polypeptide chain is twisted into a rod, with the carbonyl group H bonded to the H of the amide, which is 4 residues down the chain. Is right handed, each turn has 3.6 AA residues
2. BETA SHEETS - H bonds form between peptide chains that lie alongside each other. If adjacent strands are oriented in the SAME direction, it's a parallel beta sheet. If the strands run in the OPPOSITE direction (i.e. C-N then N-C) direction, it's a anti-parallel beta sheet.
3. BEND/LOOP - usually 4 AA's required to form the turn. Chains can fold upon themselves forming a bend/loop. Proline residues are frequently found in bends/loops.
Describe the difference between a doctor-centred & a patient-centred style of doctor.
DOCTOR-CENTRED (i.e. disease centred)
- blocking behaviour
- no acknowledgement of pt perspective
- closed q's
- inappropriate interruptions
- little empaty
- no emphasis on rapport building
- restriction of content to somatic
PATIENT-CENTRED (i.e. person centred)
- ability to elicit pt beliefs
- ability to activate the pt to take control of their illness management
- active listening
- absence of inhibiting behaviour (open q's)
- agree on problem/question
- negotiate reasonable goals
Why is good communication important? (HINT: there's 5 reasons)
Describe the circulatory principles, with reference to a central heating system.
It requires a pump (THE HEART); a series of conducting pipes (ELASTIC PIPES); smaller distributing pipes to radiators w.thermostatic controls (MUSCULAR ARTERIES & ARTERIOLES); radiators for heat exchange (CAPILLARY BEDS) & a system of return pipes that increase in diameter from the radiators back to the pump (VENULES & VEINS)
What are the 3 layers within blood vessels? (From deep to superficial)
Where does the heart lie in the body?
Lies centrally in the chest between the lungs & pleura, in the middle mediastinum is surrounded by the pericardial sac of fibrous tissue that's lined by serous slippery membrane that secretes a minuscule amount of lubricating fluid.
Describe the route of blood through the heart, starting with deoxygenated blood returning in the veins from the systemic circulation.
Enters the RA via the superior & inferior vena cava. Blood also enters from the coronary sinus.
- Deoxygenated blood passes from the RA, through the tricuspid valve, to the RV during atrial systole
- the RV pumps blood, during ventricle systole, past the pulmonary valve & into the pulmonary trunk, which divides into the L & R pulmonary arteries that go to the LUNGS allowing blood to be oxygenated
- Oxygenated blood returns from the lungs in the L&R, inf&sup, pulmonary veins to the LA
- From the LA, oxygenated blood passes through the mitral (bicuspid) valve to the LV. The atrioventricular valves are prevented from being turned inside out by papillary muscles & tendinous cords.
- the LV pumps the blood past the aortic valve & into the aorta, from where it is conducting to the entire body
Describe the coronary arteries.
Only fill during diastole because of their position behind the aortic valve
During systole, when the valve is open, the arteries are effectively switched off. Arise from aortic sinuses
Describe the coronary veins.
Apart from the anterior cardiac veins that drain directly into the RA, the veins of the heart converge on the coronary sinus, which enters the RA
What is the cardiac conduction system?
The wave of conduction (&contraction) passes from the sino atrial (SA) node, through the atria to the atrio ventricular (AV) node
- the bundle of his is the only route by which conduction may pass from the AV node & onward to the interventricular septum, where it continues into the L&R bundle branches that spread the conductino through each ventricle
What can myocardial infarction affect?
May affect the bundle of his OR the bundle branches & cause cardiac arrhythmias
What is the tertiary structure of proteins? (HINT: include what bonds are involved)
Results from a variety of interactions between the AA side chains
These interactions may include all types of bonding:
- hydrogen bonds
- van der waals interactions
- hydrophobic interactions
- ionic interactions
- disulphide bonds
Proteins are organised into multiple 'domains'. What does each domain contribute to?
A specific function to the overall protein
What is the quaternary structure of proteins? With reference to a subunit & oligomeric.
The association of more than one polypeptide
Each unit of this protein is called a subunit & the protein is referred to as a oligomeric protein. Disulphide bonds often stabilise the oligomeric structure
E.g. IgG the Ab molecule.
Describe the molecule Haemoglobin, with reference to haem molecules.
A symmetrical assembly of 2 diff subunits (2 alpha globin & 2 beta globin chains). Each of the chains (subunits) contains a haem molecule which binds oxygen for transport to tissues
Each haem molecule is held in place by H bonds from histidine F8 & the bound oxygen molecule stabilised by histidine E7.
What is the sigmoidal oxygen binding curve? How does it come about? Explain why it is sigmoidal.
Is due to cooperative binding
The affinity of the 1st O2 molecule is LOW but binding of subsequent molecule is then increased
This is due to a change in quaternary structure as the 1st O2 molecule binds
What does small changes in O2 concentration result in? What does this equate to?
Large changes in the interaction of Hb with O2
This equates to TIGHT O2 binding in the lungs & subsequent release in tissues where the O2 conc is lower
What is sickle cell anaemia caused by?
A single AA change at position 6 in the chain (glutamic acid -> valine) causing sickling due to aggregation of mutated Hb that forms stiff fibres
What is (i) tropocollagen (ii) glycine (iii) proline
(i) the building block of collagen fibre. It consists of 3 polypeptide chains with a L.hand twist wound together in a R.hand supercoil
(ii) vital for the formation of tropocollagen as its size allows for a TIGHT turn as well as close packing of subunits. It occurs every 3rd AA
(iii) also vital to tropocollagen as it imposes the R.handed twist in the helix that provides the main stabilising force
What is procollagen? What is the function of procollagen peptidase?
Formed from tropocollagen, proline & glycine
The procollagen peptidase enzyme then trims off the untwisted & unassociated ends so that all is left is the strongly twisted tropocollagen
How are molecules of tropocollagen stitched together?
By covalent cross-links (between lysines) with the help of lysl oxidase
The product is the strong collagen fibre
What is osteogenesis imperfecta? What are the symptoms?
DNA has a mutation that causes glycine to be replaced by cysteine in the collagen chain
As a consequence the tropocollagen subunits cannot pack together properly & there is a knock-on effect on collagen fibre formation
Blue tinted eyes
What are the causes of disease? (HINT: there's 4)
What is heritability? How is it measured? (HINT: there's 4 ways to measure heritability)
Measures the extent that observed differences are due to genes.
If a trait runs in families it could be due to genes, social learning, operant conditioning, chance
- family studies
- twin studies
- migrant studies
- adoption studies
Define the following; (i) Monozygotic twins (ii) Dizygotic twins (iii) Phenotype.
(i) Share the genes & environment
(ii) share same environment BUT share the same amount of genetic info as any other sibling
(iii) genes + environment + (complete interaction of the genes & environment)
What is likely to be influenced by the environment? (HINT: there's 4)
- injury from chemical agents
- injury from physical agents
Give 7 examples of (i) Infectious agents (ii) modes of transmission.
(i) bacteria, viruses, fungi, yeast, protozoa, parasites, prions
(ii) droplet, faeco-oral, venereal, blood, water, food, vectors/fomites
What are 3 types of chemical agents? What diseases can they result in?
SMOKING - cancer, COPD, increase BP & HR, endothelial damage, intrauterine growth retardation
ALCOHOL - one or two glasses can reduce the risk of heart disease, but LARGER doses increase the risk of cirrhosis
DUST - mesothelioma, coal workers' pneumoconiosis, asthma, hayfever
What are the 3 types of physical agents?
Mechanical injury - trauma
Thermal injury - hypothermia, fever (pyrexia), burn
Radiation - ionising, non-ionising (UV)
Why is it difficult to ascertain genetic vs environmental causes of disease?
Because there's alot of INTERPLAY between the genes & the environment
Describe the large arteries of the body, giving examples where appropriate.
AORTA, PULMONARY TRUNK
- mainly elastic conducting arteries
- the Ao & PT are conducting vessels that expand during systole, while elastic recoil during diastole helps to drive blood onwards
- they contain valves that prevent backflow
Describe the medium arteries of the body, giving examples where appropriate.
Femoral, Axillary, Carotid
- mainly muscular to control distribution & flow
- have a tunica media (relatively thick layer of circular smooth muscle
- distribute blood to regions & organs as well as regulating blood flow by constriction/relaxation of their walls
- have the capacity to increase greatly in diameter
What is the aortic hiatus?
A hole in the human diaphragm, at approx T12
What are the 3 main branches of the aortic arch? What does one of said branches divide into?
- which splits into the R. common carotid & R. subclavian
L. common carotid
What is the (i) Upper limb (ii) Lower limb arterial pathway?
(i) subclavian - axillary - brachial - radial & ulnar - deep & superficial palmar arch
(ii) descending aorta - common iliac - external iliac - femoral - popliteal - ant & post tibial - fibular (derived from post tibial only)
What does an arterial anastomosis ensure?
Ensures supply to the hand & fingers in ANY POSITION of the UL
ALL joints have anastomoses around them
What can plaques of atheroma lead to ? Where are they found?
May lead to the formation of a thrombus (blood clot) & vascular occlusion
What are (i) arterioles (ii) metarterioles (iii) capillaries (iv) venules (v) veins
(i) vessels with a relatively thick muscular wall & narrow lumen. Vasoconstriction & dilation control the distributino of blood to the capillary beds
(ii) pre capillary arterioles. Are vessels with a lumen that's the same diameter as capillaries, but there's only a single layer of smooth muscle surrounding the endothelium
(iii) the smallest vessels, only allow passage of a single erythrocyte. Consist of a tube of endothelium only
(iv) v.permeable wall of an endothelial lining & elastic tissue
(v) LARGER lumen & THINNER wall than arteries. Structure more variable than arteries, carry blood at low pressure.
What is the direction of venous flow?
From superficial to deep
In the lower limb, the venae comitantes converge to form what? (List up to inferior vena cava). That is the deep system, what are the 2 veins of the superficial system of the lower limbs?
Popliteal - femoral - external iliac - common iliac - inferior vena cava
Superficial = great (long) & small (short) saphenous veins
What does the median cubital vein link? What procedure is often done at this site? Why must care be taken when performing said procedure?
Links the cephalic & basilic veins across the front of the elbow joint
BLOOD is often taken at this site
- care must be taken to avoid the brachial artery & median nerve posteriorly
What does the (i) superior (ii) inferior vena cava drain?
(i) head, neck & ULs
(ii) LLs, pelvic organs, kidneys & abdominal walls
What is the importance of the lymphatic system? How is lymph filtered? Which system(s) relates to the (i) veins (ii) arteries?
Important in ensuring the removal of interstitial fluid (called lymph once in the lymph vessels)
The multitude of lymph capillaries are thin walled endothelial tubes
Lymph is filtered by lymph nodes & will eventually flow through the thoracic duct to the junction of the left subclavian & internal jugular veins.
(i) The superficial system
(ii) the deep system