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Physiology
Physiology
PrepBank · পাতা ২ / ৯ · ১০১–২০০ / ৮৮৮
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ABC of Biochemistry 6th - P:334
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Cardiac muscle fibres-
-Have single, oval, central nucleus.
-T-tubules found at the level of Z-band but in skeletal muscle T-tubules found A-I Junction.
-Intercalated disc acts as motor end in Cardiac muscle.
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ABC of Biochemistry 6th - P: 177
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★Total peripheral resistance
Directly proportional to
-Velocity
-Viscosity
-Length of blood vessels
Inversely proportional to
-Lumen of blood vessels
-4th power of radius
-Elasticity of arterial wall
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1. It is the speed at which motor and sensory impulses traverse a given segment of nerve (meter/sec)
2. Larger axons & proximal segments conduct faster than smaller ones & distal segments.
3. New born infant's nerves have slower velocities than adult.
4. CV in UL is faster than in LL
In elderly there is slowing of conduction,
in local tissue temperature slows CV.
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• Predisposing risk factors for TDP include congenital channelopathies, severe bradycardia, drugs, and hypokalemia.
• Drug-induced TDP is of major concern because it can be life threatening; class IA/III antiarrhythmic agents, antipsychotics, antibiotics, and antihistamines are among the list of drugs that are noted to destabilize repolarization.
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1. Dilutional hyponatremia, hyperkalemia and metabolic acidosis.
2. Marked insulin sensitivity and hypoglycemia.
3. Renal salt and water loss, hypotension & weight loss.
4. Hyperpigmentation of skin and buccal mucosa (due to increased ACTH following decreased cortisol).
5. Adrenal crisis (Addisonian crisis)
It is the state of acute adrenocortical insufficiency in patients with Addison’s disease who are exposed to the stressful conditions like infection, trauma surgery, vomiting, diarrhoea etc. Patients become confused, disoriented and eventually develop severe hypotension and shock.
Ref: ABC 6th/P-510
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Atrial systole initiates cardiac cycle because the sinus node (pacemaker) of the heart is located in the right atrium.
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1. Growth of adrenal cortex.
2. Stimulation of glucocorticoid secretion.
3. Mild stimulation of adrenal androgen secretion.
4.Stimulates melanocytes and causes skin pigmentation
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1. Glucagon
2. Cortisol
3. Epinephrine & Norepinephrine
4. Growth hormone
5. Thyroid hormone
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Islets of Langerhans consist of four types of cells:
A cells or α-cells, which secrete glucagon
B cells or β-cells, which secrete insulin
D cells or δ-cells, which secrete somatostatin
F cells or PP cells, which secrete pancreatic polypeptide.
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Reticulocyte is otherwise known as immature RBC. It is slightly larger than matured RBC. The cytoplasm contains the reticular network or reticulum, which is formed by remnants of disintegrated organelles. Due to the reticular network, the cell is called reticulocyte. The reticulum of reticulocyte stains with supravital stain.
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★Examples of Secondary active transport-
-Na+-Ca++ counter transport
-Na+-H+ counter transport
-Chloride shift
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Site of gluconeogenesis: a.Liver 90%
b.Kidney 10%
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★ The insulin receptor in target tissues is a tetramer. The two β subunits have tyrosine kinase activity and autophosphorylate the receptor when stimulated by insulin.
Reference-Ganong physiology/26th/P-424 &BRS physiology/6th/P-249/Fig-7.3
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Apoprotein 50 %
Apo A
Apo C
Apo E
Lipid 50%
ABC of Biochemistry 6th - P: 218
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Most of plasma protein is synthesized from liver except gamma globulin from plasma cells.
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Ref : Sembulingam 6th edition (Page- 783)
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Innervation
Sensory: lacrimal nerve (from ophthalmic nerve)
Parasympathetic: greater petrosal nerve (from facial nerve)
Sympathetic: deep petrosal nerve (from internal carotid plexus)
Snell 8th - 415 Review Q- 15
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Ref : Sembulingam 6th edition (Table- 141.1)
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Ref : Sembulingam 6th edition (Page- 1025)
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1 a wave - representing atrial systole;
2 c wave - representing closure of the tricuspid valve (this wave is not usually visible);
3 x descent - representing a fall in atrial pressure during ventricular systole;
4 v wave - representing atrial filling against a closed tricuspid valve;
5 y descent - representing the opening of the tricuspid valve.
In atrial fibrillation, the 'a waves' are absent (D) due to dysfunctional atrial systole. A raised JVP with normal waveform pattern (A) is usually seen in fluid overload and right heart failure. Large v waves (B) are usually seen in patients with tricuspid regurgitation. Cannon 'a waves' (C) are seen in patients with complete heart block, single chamber ventricular pacing, ventricular arrhythmias and ventricular ectopics. Large 'a waves' (E) can be seen in pulmonary hypertension and pulmonary stenosis.
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About 10% of the total blood volume can be removed with almost no effect on arterial pressure or cardiac output, but greater blood loss usually diminishes the cardiac output first and falls to zero when about 40% to 45% of the total blood volume has been removed.
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determining cardiac output, the various factors of the peripheral circulation that affect flow of blood into the heart from the veins, called venous return, are normally the primary controllers of cardiac output.
(Ref. Guyton & Hall-14th, P-245
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1) The first source of energy that is used to reconstitute the ATP is the substance phosphocreatine, which carries a high-energy phosphate bond similar to the bonds of ATP.
2) The second important source of energy, which is used to reconstitute both ATP and phosphocreatine, is a process called glycolysis-the breakdown of glycogen previously stored in the muscle cells.
3) The third and final source of energy is oxidative metabolism, which means combining oxygen with the end products of glycolysis and with various other cellular foodstuffs to liberate ATP.
More than 95% of all energy used by the muscles for sustained long-term contraction is derived from oxidative metabolism.
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Factors increased influx of K+ -
-Insulin
-Aldosterone
-Acute potassium excess
-Alkalosis
-Epinephrine
-Alpha blocker
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The capillaries in the alveolar walls are distended by the blood pressure inside them but simultaneously are compressed by the alveolar air pressure on their outsides. Therefore, whenever the lung alveolar air pressure becomes greater than the capillary blood pressure, the capillaries close, and there is no blood flow.
Under different normal and pathological lung conditions, one may find any one of three possible zones (patterns) of pulmonary blood flow, as follows:
Zone 1: No blood flow during all portions of the cardiac cycle because the local alveolar capillary pressure in that area of the lung never rises higher than the alveolar air pressure during any part of the cardiac cycle
Zone 2: Intermittent blood flow only during the peaks of pulmonary arterial pressure because the systolic pressure is then greater than the alveolar air pressure, but the diastolic pressure is less than the alveolar air pressure
Zone 3: Continuous blood flow because the alveolar capillary pressure are remains greater than alveolar air pressure during the entire cardiac cycle
Normally, the lungs have only zones 2 and 3 blood flow-zone 2 (intermittent flow) in the apices and zone 3 (continuous flow) in all the lower areas.
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The resonators include the mouth, the nose and associated nasal sinuses, the pharynx, and even the chest cavity.
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In the usual Na+ gradient, the [Na+] is higher in extracellular than in intracellular fluid (maintained by the Na+–K+ pump). Two forms of transport are energized by this Na+ gradient cotransport and countertransport. Because glucose is moving in the same direction as Na+, one can conclude that it is cotransport.
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Maintenance of its composition depends on the blood-testis barrier. The barrier also protects the germ cells from bloodborne noxious agents, prevents antigenic products of germ cell division and maturation from entering the circulation and generating an autoimmune response, and may help establish an osmotic gradient that facilitates movement of fluid into the tubular lumen.
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Explanations:
Factor increasing ESR
• Specific gravity of RBC
• Rouleaux formation
• Increase in size of RBC
Factors decreasing ESR:
• Viscosity of blood
• RBC count
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Explanation : Acetylcholine is the transmitter substance at the neuromuscular junction and synapse. It is also released by the following nerve endings:
1. Preganglionic parasympathetic nerve
2. Postganglionic parasympathetic nerve
3. Preganglionic sympathetic nerve
4. Postganglionic sympathetic cholinergic nerves:
i. Nerves supplying eccrine sweat glands
ii. Sympathetic vasodilator nerves in skeletal muscle
5. Nerves in amacrine cells of retina
6. Many regions of brain.
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Ref : Sembulingam 6th edition (Page- 783, 784)
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Islets of Langerhans consist of four types of cells:
A cells or α-cells, which secrete glucagon
B cells or β-cells, which secrete insulin
D cells or δ-cells, which secrete somatostatin
F cells or PP cells, which secrete pancreatic polypeptide.
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Explanation : Horner syndrome is an eye disorder caused by damage to cervical sympathetic nerve. It is also called Bernard-Horner syndrome, Claude- Bernard-Horner syndrome or oculosympathetic palsy. Symptoms of Horner syndrome appear on the affected side. The symptoms are:
1. Ptosis (drooping of upper eyelid)
2. Swelling of lower eyelid
3. Miosis (abnormal constriction of pupil)
4. Enophthalmos (sinking of eyeball into its cavity)
5. Absence of sweating on affected side of the face.
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1. Primary auditory area, which includes area 41, area 42 and Wernicke area.
2. Secondary auditory area or auditopsychic area, which includes area 22
Ref : Sembulingam 6th edition (Page- 1014)
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Sarcoplasmic reticulum (SR) is the internal tubular structure that is the site of Ca2+ storage and release for excitation-contraction coupling. It has terminal cisternae that make intimate contact with the T tubules in a triad arrangement.
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Following can be taken as a measure of GFR:
1. Inulin clearance
2. Creatinine clearance and
3. Urea clearance
Inulin clearance – the gold standard of physiologists - is not practical or necessary in clinical practice. Clinically creatinine clearance is widely used. Urea clearance is not an accurate measure of GFR
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Pulse pressure (PP)
-PP Directly proportional to SV
-PP inversely proportional to compliance/Arterial elasticity
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Thirst center is stimulated by-
-Intracellular dehydration
-Hypovolemia
-Angiotensin-2 in circulation
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Cardiovascular changes following birth are-
-Increase arterial oxygen tension
-Decreased Pulmonary vascular resistance
-Increased Pulmonary blood flow
-Increased systemic vascular resistance
-Closure of Ductus arteriosus and ductus venosus
-closure Foramen ovale
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Hb S, Hb C, Hb H, Hb Barts are abnormal Hb.
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Ref : BRS Physiology 7th edition (Table-2.5)
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Cys-Tyr-Phe-Gln-Asn-Cys-Pro-Arg- GlyNH2
Oxytocin:
Cys-Tyr-Ile-Gln-Asn-Cys-Pro-Leu-GlyNH2
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Rickets, Fragile-X syndrome—X-linked dominant
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Characteristics:
• It is short and low pitched sound.
• Duration of the sound is 0.02 -0.04 seconds.
Causes:
• It occurs due to vibrations which set up in atrial musculature during atrial systole.
Fourth heart sound and ECG:
• It coincides with interval between end of 'P' wave and onset of 'Q' wave in ECG.
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Ø Gluconeogenesis that provides glucose to be used as fuel in neurons.
Ø Proteolysis that provides amino acid to support gluconeogenesis and acute phase protein synthesis in liver.
Ø Lipolysis that provides fatty acid to be used as fuel in peripheral tissues.
Ø Maintenance of ECF volume and blood pressure.
* For these functions in relation to stress, cortisol is called emergency hormone
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megaloblastic anaemia secondary to vitamin B12 and folic acid deficiency;
chronic alcoholism and/or alcoholic liver disease (most common causes of all causes of macrocytosis), pregnancy, hypothyroidism, reticulocytosis, aplastic anaemia, myelodysplastic syndromes and can also be caused by drugs that inhibit DNA synthesis (e.g. azathioprine);
an elevated MCV would suggest, along with the deranged LFTs, and support a diagnosis of alcoholic liver disease.