MRCEM Primary > Cellular Physiology > Flashcards

Cellular Physiology Flashcards

(78 cards)

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1
Q

Which is the most common extra cellular cation?

A

Na

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2
Q

Muscle cells grouped together are called?

A

Fasciculi

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3
Q

What is the Osmol gap?

A

Osmolar gap is the difference between measured osmolality and the calculated osmolarity.

osmolarity/osmolality should be similar and the difference should be <10. Gaps >10 are abnormal and indicate osmotically active substances - Manntiol, Methanol, ethylene glycol, sorbitol, glycine.

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4
Q

Which cells are the primary phagocytoser of platelets in the liver?

A

Kupffer cells

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5
Q

What is normal plasma osmolality?

A

290 mosmo/kg

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6
Q

What sort of receptors to Adrenaline and Norad bind to?

A

G protein coupled adrenergic receptors which activate cAMP

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7
Q

How do you calculate osmolarity?

A

2Na + 2K + glucose + urea

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8
Q

What is the typical concentration of free Ca ions in cytosol?

A

0.0001mmol/L as it is almost always pumped out of the cell or into Organelles.

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9
Q

What is the size of an RBC?

A

6-8 microns.

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10
Q

Reticulocytes account for how much of the RBC population?

A

0.5-2%

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11
Q

What is the protein chain make up of Haemoglobin?

A

2 alpha and 2 beta chains

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12
Q

What is the role of Thrombomodulin?

A

Binds thrombin and activates protein C inactivating factors Va and VIIIa and tenase

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13
Q

What is the main component of the Reticuloendothelial system?

A

Macrophages, located predominantly in the Liver

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14
Q

What is Ca2+ bound to in the sarcoplasmic reticulum?

A

Calsequestrin

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15
Q

How is Ca released from the Sarcoplasmic reticulum?

A

Ca which is pumped in and is essential for contraction opens the calcium proteins which release Ca from the Sarcoplasmic reticulum.

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16
Q

Foetal Haemoglobin makes up how much of circulating Hb in Adults?

A

0.5-0.8%

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17
Q

What is Foetal haemoglobin made up of?

A

two alpha and two gamma chains.

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18
Q

What is the functional unit of a muscle?

A

The Sarcomere

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19
Q

What is the I band

A

The I band extends from extends from either side of the Z line to the start of the thick myosin filament.

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20
Q

What is the main factor which stimulates fibrinolysis?

A

Tissue Plasminogen activator (tPA)

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21
Q

What are the causes of low anion gap metabolic acidosis?

A

Hypoalbuminaemia
Myeloma
hypercalcaemia
Hypermagnaesaemia
Lithium OD
Bromide OD

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22
Q

What proportion of fluid is intracellular?

A

2/3rds

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23
Q

What portion of fluid is extracellular?

A

1/3

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24
Q

What portion of Extracellular fluid is plasma?

A

20-35%

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25
What proportion of fluid is interstitial?
65-80%
26
What percentage of cardiac output does the liver receive?
25%
27
The sympathetic preganglionic neurones are located where?
Lateral horns of spinal segments T1-L2
28
What do Sympathetic postganglionic neurones release?
Noradrenaline
29
What factors affect the diffusion coefficient?
Molecule size Temperature Solvent viscosity Molecular weight
30
What is the role of VWF?
Promotion of platelt adhesion, platelet aggregation and is the carrier protein for Clotting factor VIII
31
What is the resting action potential of a neuron?
-70mV
32
What is the threshold potential
33
When do voltage gated K+ channels open?
+40mV
34
How long is the Refractory period?
1ms
35
How is the force of contraction of a muscle controlled?
Variation in Motor unit recruitment - Spatial summation and varying the firing rate of motor units, temporal summation.
36
What is the neuronal firing rate for a steady contraction?
5-8Hz
37
What is the lifespan of a platelet?
10 days
38
What types of granule are in platelets?
1) Platelet Dense Granules: containing ADP, ATP, Serotonin, calcium 2) Alpha Granules containing clotting factors, vWF, platelet-derived growth factor PDGF 3) Lyosomes with hydrolytic enzymes.
39
What cells are involved in the production of a platelet?
Haematopoietic stem cell Promegakaryocyte Megakaryocyte
40
What is Kussmaul respiration?
Deep rapid gasping which is a respiratory stimulant
41
Which Clotting Factors are used in the intrinsic pathway?
XII, XI, IX, VIIIa, X, V
42
What causes the intrinsic pathway to be activated?
Damaged vessel walls
43
What causes the extrinsic pathway to be activated?
Trauma to extravascular cells
44
What is the purpose of the coagulation cascade?
End result is production of Fibrin which enmeshes the platelet aggregates at the sites of vascular injury and convert a platelet plug into a haemostatic plug.
45
What is the function of the macular densa?
Respond to the concetration of tubular fluid (Na+ ions)
46
What causes low Reticulocyte count?
General bone marrow failure Impaired RBC production Lack of EPO Chronic systemic disease
47
What makes up the thin and thick filaments in a sarcomere?
Actin - thin Myosin - thick
48
The I band makes up what portion of a sarcomere?
The gap between Myosin filaments.
49
The H zone contains what part of a sarcomere?
The gap between the actin filaments
50
The Unit of a singular sarcomere is measured from what to what?
Z disc to Z disc - where actin fibres cross over.
51
The Thin Descending limb of the loop of henle is permeable to what?
Water Impermeable to NaCl and Urea
52
How many molecules of ATP are produced in Aerobic respiration?
38
53
What is the role of Oxygen in the electron transfer system?
Oxygen is the final hydrogen acceptor for H+ ion gradients - to form water.
54
What is calcium normally bound to?
45% of calcium is bound to Albumin.
55
Where does free ionised Calcium bind to?
negatively charged sites on proteins - it competes with H+ Therefore acidosis causes increased Calcium Alkalosis causes decreased calcium.
56
What are the components of a negative feedback mechanism?
Detector (neural receptor cells usually) Comparator (Compare the variable to a set point) Effector (muscular or glandular tissue)
57
What causes EPO production?
Low oxygen tension in the tissues of the kidneys
58
What percentage of Bicarbonate is reabsorbed?
80% reabsorbed at the PCT
59
Where is renin produced?
Granular cells in the wall of the afferent arteriole
60
Where does the Kreb's cycle take place?
Matrix of the mitochondria
61
What are the features of Hypokalaemia?
Muscle weakness - cramps and Rhabdomyolysis Ascending paralysis resulting in respiratory failure Constipation Gut Ileus with distension, anorexia, Nause adn vomiting Impaired ADH action with polyuria and polydipsia ECG changes
62
What is the role of Protein C and S
They inhibit coagulation co factors V and VIII This enhances Fibrinolysis as it destroys plasma inhibitors of tPA
63
What does calcium bind to to cause contraction?
Troponin.
64
What is the countercurrent multiplier?
Blood supply to the medulla is prevented from dissipating the osmotic gradient between the cortex and medulla by the vasa recta capillaries.
65
What are the major haemopoietic organs in the foetus from 6 week to 6-7 months gestation?
Liver and spleen
66
Sympathetic Preganglionic neurones release what Chemical receptor?
Acetylcholine
67
What is the make up of HbA2?
2 alpha and 2 delta subunits
68
What is the make up of HbF?
2 alpha and 2 gamma
69
Gene mutations would change a what part of a protein structure?
Primary Protein structure.
70
The Gibbs Donna equilibrium describes what?
The repellent force between ions of the same charge is balanced by the movement of ions back along its concentration gradient.
71
What enzyme breaks down Haem into Biliverdin?
Haem Oxygenase
72
Which enzyme reduces Biliverdin into Bilirubin?
Biliverdin Reductase
73
What are the functions of the parasympathetic nervous system?
SSLUDD Sexual arousal Salivation Lacrimation Urination Digestion Defecation
74
What are the chemicals which inhibit haemostasis?
Prostacyclin Nitric Oxide Antithrombin Thrombomodulin Plasmin
75
How do Natural Killer Cells function?
Release cytotoxic molecules from Secretroy lysosomes
76
What is Osmolarity?
Osmoles of solute per litre solution
77
What is Osmolality?
Osmoles of solute per Kg solvent
78
Whats the difference between Primary vs Secondary active transport?
Primary uses ATP hydrolysis whereas secondary uses energy in other forms that are not ATP - usually a Symporter or antiporter.
MRCEM Primary
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