Clinical Conditions Flashcards
What is thyrotoxicosis?
- Thyrotoxicosis is a disease caused by excessive concentrations of free thyroid hormones (most often T4)
- It presents with tremor, tachycardia, fatigue and heat intolerance
What is hyperthyroidism?
- Hyperthyroidism is an endocrine disorder wherein the thyroid gland is overactive and produces an excess amount of T3/T4
- It presents with fatigue, weight loss and excessive sweating
What is hypothyroidism?
- Hypothyroidism is an endocrine disorder wherein the thyroid gland is underactive and produces an insufficient amount of T3/T4
- It presents with tiredness, weight gain and feeling depressed
What is asthma?
Asthma is a long-term inflammatory disorder of the lungs characterised by airway hyper-responsiveness which causes variable and reversible airflow obstruction
Name and explain 2 haemolytic anaemias.
Hereditary sperocytosis:
- Spectrin depleted 40-50%
- Erthrocytes=more round
- Less resistant to lysis
Hereditary eliptocytosis:
- Defect in spectrin molecule
Name 2 toxins which interfere with G-protein function
- Cholera toxin
- Pertussis toxin
How does the pertussis toxin work?
Corrupts Gαi protein- uncouples it
How does the cholera toxin work?
Prevents GTPase activity
Permanently ON pathway
(Corrupts GalphaS)
Loss of fluid and electrolytes
Explain how interactions with ß1 -adrenoreceptors can increase the force of contraction in the heart.
(positive inotropic effect)
G alpha S subunit- active- acitivates adenylyl cyclase
Adenylyl cyclase- ATP to Cyclic AMP
Cyclic AMP- activates PKA
PKA causes complement modification of VOCC
Higher intracellular Ca2+ conc
Increased contractility
How can sympathetically release noradrenaline cause vasoconstriction (smooth muscle contraction)?
Acting on: α₁-adrenoreceptors
How can parasympathetically released acetylcholine cause bronchoconstriction?
Act on: M3-muscarinic receptor
What are the normal plasma levels of calcium?
8-10mg/dL
1.9-2.3mM
What processes are changes in calcium ion concentration responsible for?
- Muscle contraction
- Neurotransmission
- Fertilisation
- Cell death
- Metabolism regulation
- Learning and memory
Name the different types of calcium ion transporters
- PMCA: Plasma membrane calcium ATPase (ATP dependent)
- SERCA: Sarcoplasmic ER calcium ATPase (ATP dependent)
- NCX: Sodium-calcium exchanger
- VOCC: Voltage operated calcium channel (influx)
- LGIC: Ligand gated ion channels
-
CICR: Calcium induced calcium release receptors
- amplify Ca2+ change in cytoplasm (ER/SR release)
- IP3R: receptors (ER/SR release)
Which of the following can Na+ and K+ pass through (without proteins etc)?
- Capillary wall
- Cell membrane
Capillary wall - not cell membrane
What is the normal osmolarity of intracellular fluid?
280-310mOsm/kg
How is serum osmolarity estimated clinically?
Doubling serum sodium
What is the Permeability coefficient?
Transport flux of material through membrane per unit driving force per unit membrane thickness
What do each of the letter stand for in this equation?
J = P (C1 - C2)
J= net rate of transport
P= permeability coefficient
C=concentration
Which of the following ions is higher intracellularly than extracellularly?
- Na+
- Cl-
- K+
- Ca2+
K+
What are 2 types of co-transporters?
Symport - same direction
Antiport- opposite direction
What does sodium-potassium ATPase do?
Generates ion gradients
Allows for:
- secondary active transport
- action potentials
Why does calcium end up entering the cell in an uncontrolled way in ischaemia?
- Low oxygen
- Low ATP production
- Gradients of Na+ not maintained
Name 3 membrane proteins which control cell pH.
-
Acid extruders:
-
NHE: Sodium/hydrogen exchanger
- 1:1
- Activated by growth factors
- Inhibited by amiloride
- NBC: Sodium bicarbonate co-transporter
-
NHE: Sodium/hydrogen exchanger
-
Base extruders:
-
AE: Anion exchanger
- Exchange Cl- with HCO3-
-
AE: Anion exchanger
What is often the first line of treatment for mild hypertension?
Renal control of circulating Na+ concentration
EG.
- Water tablet conc
- Diuretic
Which cells in the body have the highest resting membrane potentials?
Cardiac and skeletal muscle cells
(-80–> -90 mV)
What are the ionic concentrations for a typical cell of:
Na+
K+
Cl-
Anions (-) eg phosphate, bicarbonate, amino acids
- Na+
- Intracellular: 12mM
- Extracellular: 145mM
-
K+
- Intracellular: 155mM
- Extracellular: 4.5mM
- Cl-
- Intracellular: 4.2mM
- Extracellular: 123mM
- Anions (-) eg phosphate, bicarbonate, amino acids:
- Intracellular: 167mM
- Extracellular: 40mM
-
Intracellular:
- Extracellular:
-
Intracellular:
What does the nernst equation allow us to calculate?
Membrane potential
What is the GHK equation and what does it describe?
Goldman-Hodgkin-Katz
Describes the ionic flux across a cell membrane as a function of the transmembrane potential and the concentrations of the ion inside and outside of the cell.
What are the 2 types of fast synaptic transmission?
(Receptor protein=ion channel–>
Transmitter binding- opens channel)
-
EPSP: Excitatory post-synaptic potential
- Excitatory transmitters (eg acetylcholine, glutamate) open ligand gated ion channels- caused membrane depolarisations
-
Inhibitory synapses
- Transmitters (glycine)- Open ligand-gated channels- cause hyperpolarisation
What are the 2 types of slow synaptic transmission?
-
Direct G-protein gating
- Localised, quite rapid
- Gating via intracellular messenger
What is Devic’s disease?
Conduction of action potential in CNS affected (optic and spinal nerves) due to break down of myelin sheath.
Name 2 diseases which affect the PNS and cause breakdown or damage to the myelin sheath.
Landry-Guillain-Barre syndrome
Charcot-Marie-Tooth disease
