The Patient - Semester 1

Question 1

Define Pharmacokinetics, Pharmacodynamics and Pharmacotherapeutics and explain how they are related

Answer 1

• Kinetics: How the body metabolises the drug
• Dynamics: The changes the drug causes in the body
• Therapeutics: The use of drugs to treat and prevent disease
• Kinetics+Dynamics=Therapeutics

Question 2

How do drugs and receptors interact?

Answer 2

• Drug-receptor interactions cause an effect in the body
• Drugs target specific receptors
• Affinity for the receptor affects the extent of the response (depends on charge)

Question 3

What are agonists? What can effect how they bind?

Answer 3

• Have affinity and efficacy for a particular receptor/enzyme
• Can be full, partial or inverse (type of response)
• Allosteric modulators affect the binding of an agonist and can have a positive, negative or neutral response

Question 4

What are antagonists? Describe their relationship with an agonist

Answer 4

• Competitive or non-competitive inhibitor for the same target protein as an agonist
• If an antagonist forms covalent bonds with the target protein the inhibition is permanent
• Causes no response
• If an agonist is present in excess, the affinity is usually higher

Question 5

What molecules are drug targets usually?

Answer 5

Proteins - generally receptors

Question 6

How does the GPCR work?

Answer 6

• Receptor forms complex with alpha-GDP complex
• GDP exchanged for GTP
• Alpha-GTP dissociates from G protein and binds to a target protein in the cell
• GTP is hydrolysed
• Alpha subunit rejoins the other subunits of the G protein

Question 7

How does Digoxin increase contraction force?

Answer 7

• Na+/K+ ATP-ase blocked
• Na+/Ca2+ exchanger stimulated by increase in [Na+]
• [Ca2+] increases causing an increase in contraction force

Question 8

How do antagonists affect the dose of an agonist required?

Answer 8

• If competitive antagonist, higher dose is required to achieve same effect
• If non-competitive antagonist, same effect cannot be achieved

Question 9

Describe the anatomy of the cardiovascular system

Answer 9

• Heart consists of four chambers, two atria and two ventricles
• AV valves, aortic valve and pulmonary valve prevent back flow of blood
• Lungs supplied with blood by pulmonary circuit
• Body supplied from systemic circuit

Question 10

Describe diastole and systole

Answer 10

• Diastole: Cardiac muscle is relaxed, low pressure in ventricles causes them to fill
• Systole: Contraction of each set of chambers increasing the pressure in each, pressure changes cause valves to shut to prevent backflow

Question 11

What factors determine the cardiac output?

Answer 11

• Venous filling pressure

- Autonomic nervous input

Question 12

Define preload and afterload

Answer 12

• Preload: Ventricular stretch caused by filling, more energy required when preload is bigger
• Afterload: Arterial pressure to overcome to open aortic valve, energy required increases with afterload

Question 13

What is the stroke volume?

Answer 13

Difference in ventricular volume between the end of systole and the end of diastole

Question 14

What are functions of the vascular system and how does it work synergistically with the heart?

Answer 14

• Supplying the tissues with nutrients and oxygen

- Heart controls blood flow and pressure to ensure sufficient exchange

Question 15

What are haemodynamics?

Answer 15

The physics of blood flow

Question 16

Define flow resistance and list the factors that alter it

Answer 16

• The relationship between blood pressure and blood flow
• Viscosity (directly proportional)
• Vessel length (directly proportional)
• Vessel diameter (indirectly proportional)

Question 17

Why does branching of vascular system occur?

Answer 17

• Flow remains the same while vessel diameter decreases

- Branching of smaller vessels reduce the drop in pressure as a result of this

Question 18

Describe the different structures of the vessels

Answer 18

• Veins: Thin smooth muscle layer, connective tissue, large endothelium
• Arteries: Thick smooth muscle layer, connective tissue, smaller endothelium
• Capillaries: Single cell epithelium

Question 19

What is the effect of smooth muscle muscle contraction on resistance and venous pressure?

Answer 19

Both increase

Question 20

Define compliance (blood vessel)

Answer 20

The effect of internal pressure on the stretching of the vessel wall

Question 21

How do cardiac cells exhibit electrical activity?

Answer 21

• Ion concentration gradients allow electrical energy

- Cells are highly conductive

Question 22

Explain the difference between the activity of pacemaker and contractile cells

Answer 22

• Pacemaker cells continuously produce action potentials

- Contractile cells produce action potentials intermittently

Question 23

What is the equilibrium potential?

Answer 23

The electrical potential at which the chemical potential is at an equilibrium

Question 24

What alters the shape of an action potential of a cardiac cell?

Answer 24

Combination of ion channels in the lipid membrane