Remarkable Rapid Revision Physiology By Dr Sree Teja || FMGE and Neet Pg 2024

Dr.G Bhanu Prakash Animated Medical Videos135 minutes read

The video covers essential physiology topics for exams, focusing on efficient learning through a question-answer format, equipping students to answer questions without extensive studying. Different topics like cell membrane composition, clotting factors, endocrine system, cardiac cycle, respiratory physiology, and renal physiology are discussed in detail, providing a comprehensive overview of crucial concepts for exams.

Insights

  • Watching the video in high resolution is essential for better clarity and understanding.
  • Physiology revision in the video aims to condense crucial exam topics for efficient learning.
  • The video focuses on equipping students to answer exam questions without extensive study.
  • Physiology exams typically include 8 to 9 questions, emphasizing the importance of the subject.
  • The teaching style in the video is direct, utilizing a question-answer format for effective learning.

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Recent questions

  • What is the main function of surfactant in the lungs?

    Protects by decreasing surface tension, preventing collapse.

  • How does the oxygen-hemoglobin dissociation curve respond to different conditions?

    Shifts left or right, affecting oxygen delivery to tissues.

  • What is the role of the Frank-Starling law in cardiac function?

    Increasing end-diastolic volume boosts stroke volume.

  • What is the main function of the parathyroid hormone?

    Increases calcium levels in the body.

  • How does the body compensate for decreased oxygen levels at high altitudes?

    Increased ventilation and perfusion, leading to respiratory alkalosis.

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Summary

00:00

Physiology Exam Prep: High-Resolution Video Review

  • The instructor emphasizes watching the video in high resolution for better clarity.
  • The session is a rapid revision of physiology, condensing essential topics for exams.
  • The video aims to equip students to answer exam questions without needing to study extensively.
  • Physiology typically carries a weightage of 8 to 9 questions in exams.
  • The teaching style in the video is direct, focusing on question-answer format for efficient learning.
  • The session covers topics like cell membrane composition, with proteins making up 55%.
  • Integral and peripheral proteins are discussed, with examples like anine and spectrin in RBCs.
  • The absence of proteins like dropin can lead to conditions like muscular dystrophy.
  • Lipids in the cell membrane consist mainly of phospholipids, with specific types like cardiolipin.
  • Phospholipids like phospho-Serine serve as markers for cell processes like apoptosis.

18:27

Cell Structure, Transport, and Blood Coagulation Overview

  • Microfilament examples are actin and myosin, present in every cell, providing structure to the cell.
  • Intermediate filaments like keratin, desmin, vimentin, and GFAP are cell-specific, giving support to specific cell types.
  • Transport mechanisms include active transport requiring energy and passive transport not needing energy.
  • Primary active transport examples involve ATP, pumps like sodium-potassium ATPase, calcium ATPase, and proton ATPase.
  • Secondary active transport examples include co-transporters, symporters, and antiporters.
  • Glucose transporters (GLUTs) are crucial for facilitated diffusion, with GLUT4 being insulin-responsive.
  • Fructose transporters include GLUT5 and GLUT11, specific to fructose transport.
  • Total body water is around 60% of body weight, measured using indicators like deuterium oxide and inulin.
  • Stuart-Hamilton method uses indicator dilution principle to calculate total body water.
  • Blood coagulation involves intrinsic, extrinsic, and common pathways, with clotting factors activating each other to form clots.

37:04

Clotting Factors and Hormones in Physiology

  • Clotting Factor 7 is extrinsic, Factor 8 is intrinsic, and Factor 1 converts fibrinogen.
  • Vitamin K activates clotting Factors 2, 7, 9, 10 through gamma carboxylation.
  • Vitamin K is crucial for gamma carboxylation of Factor 2, 7, 9, 10.
  • Clotting Cascade is vital for clotting process.
  • Endocrine physiology is significant for exams, with 3 questions from endocrine.
  • Steroid hormones are derived from cholesterol, including testosterone, estrogen, progesterone, aldosterone, and cortisol.
  • Steroid hormones cross cell membranes and have intracellular receptors.
  • T3 and T4 thyroid hormones also have intracellular receptors.
  • Different hormones increase secondary messengers like cAMP, cGMP, and IP3.
  • Insulin and Insulin-like growth factor use tyrosine kinase receptors.

56:17

Endocrine System: Hormones and Cell Functions

  • Cells stained with H and E stain will appear pink, known as acidophilic cells, including somatotropes and lactotropes.
  • Oxytocin aids in uterine contractions for delivery and milk ejection post-delivery.
  • Prolactin functions in lactogenesis, inhibiting GnRH, FSH, and LH production, aiding in breast development and inhibiting spermatogenesis.
  • Hypothalamus releases GnRH, stimulating gonadotropes to produce FSH and LH, acting on Sertoli and Leydig cells in the testes.
  • Leydig cells produce testosterone, converted to dihydrotestosterone by 5-alpha reductase, aiding in spermatogenesis.
  • Sperms acquire motility in the epididymis.
  • Growth hormone increases blood glucose levels, protein synthesis, and causes lipolysis, stimulated by GHRH and inhibited by somatostatin.
  • Thyroid hormones increase basal metabolic rate, requiring more calories, bound to thyroid binding globulins, and produced through oxidation, organification, and coupling reactions by thyroid peroxidase.
  • Propranolol inhibits thyroid peroxidase.
  • Adrenal gland's cortex produces aldosterone, cortisol, and androgens, while the medulla produces epinephrine and norepinephrine. Aldosterone increases sodium reabsorption, cortisol aids in stress response and decreases most WBCs except neutrophils and monocytes.

01:16:13

Hormones and enzymes in physiological processes.

  • Cortisol increases RBC and platelet count, while decreasing other WBC except neutrophils and monocytes.
  • Parathyroid hormone is produced by the parathyroid gland, while calcitonin is produced by parafollicular cells in the thyroid gland.
  • Parathyroid hormone increases calcium levels, while calcitonin decreases calcium levels, acting as physiological antagonists.
  • Vitamin D increases both calcium and phosphate levels, while parathyroid hormone decreases phosphate levels.
  • Insulin activates reactions that decrease blood glucose levels, including glycogen synthesis, lipogenesis, and glycolysis.
  • Insulin inhibits reactions that increase blood glucose levels, such as glycogenolysis, gluconeogenesis, and lipolysis.
  • In type 1 diabetes mellitus, insulin deficiency leads to diabetic ketoacidosis, treated with intravenous insulin to prevent cerebral edema.
  • Meissner's plexus and Auerbach's plexus in the intestine control secretions and contractions, absent in Hirschsprung's disease, often seen in Down syndrome.
  • Saliva, mainly produced by the submandibular salivary gland, contains salivary amylase for carbohydrate digestion and lingual lipase for lipid digestion.
  • Stomach cells include parietal cells producing acid and intrinsic factor, chief cells producing pepsinogen and gastric lipase, and D cells producing somatostatin to decrease acid levels.

01:36:35

Gastrointestinal and Cardiac Physiology Essentials

  • Bile is released, causing gallbladder contraction and secretion from Brunner glands in the duodenum.
  • Brunner glands produce highly alkaline secretion with a pH of 8 to 9, aiding in digestion.
  • Pancreas produces enzymes like pancreatic amylase, trypsin, and chymotrypsin for digestion.
  • Colipase, a pancreatic lipase, helps digest fats and is produced by the pancreas.
  • Basal electrical rhythm in the gastrointestinal tract is regulated by interstitial cells of Cajal.
  • Parasympathetic nervous system activation leads to spike potentials, causing gastrointestinal contractions.
  • Migratory Motor Complex (MMC) cleans the gastrointestinal tract during fasting, mediated by motilin.
  • Segmentation and peristalsis are two types of contractions in the fed state for food propulsion and mixing.
  • Heart sounds S1 and S2 occur during specific phases of the cardiac cycle, with S3 and S4 indicating pathology.
  • Murmurs like holosystolic, crescendo-decrescendo, and continuous machinery are associated with specific heart conditions.

01:55:57

Cardiac Cycle: Blood Ejection and Ventricular Relaxation

  • Left ventricle always fills with 50 ml of blood
  • Left ventricle fills with 120 ml of blood during contraction
  • Pressure in the left ventricle increases to 80 mmHg during contraction
  • Iotic valve opens when pressure reaches 80 mmHg
  • Blood is rapidly ejected when pressure reaches 120 mmHg
  • Slow ejection phase follows rapid ejection phase
  • Pressure decreases as blood slowly ejects during slow ejection phase
  • Left ventricle relaxes during isovolumetric relaxation phase
  • Jugular venous pressures have five waves: A, C, X, V, Y
  • A wave seen during atrial contraction, X wave during relaxation, C wave during ventricular contraction, V wave during atrial filling, Y wave during atrial emptying

02:17:20

Cardiac Cycle: Pressure, Flow, and Regulation

  • Left ventricle contracts, leading to increased blood flow into the aorta and arteries, causing pressure to rise.
  • During rapid ejection phase, more blood enters, further increasing pressure.
  • In slow ejection phase, less blood flows, resulting in decreased pressure.
  • The aortic wall closes after slow ejection phase, causing pressure to drop.
  • The aorta squeezes to push blood forward, briefly increasing pressure.
  • The pressure wave resembles a pulse, with pressure fluctuating.
  • The dicrotic notch occurs when the aortic wall closes, increasing pressure due to elastic recoil.
  • Closure of the aortic valve causes the second heart sound, A2.
  • Frank-Starling law states that increasing end-diastolic volume boosts stroke volume.
  • Cardiac reflexes like Cushing's and Bainbridge reflexes regulate heart rate based on various stimuli.

02:36:35

"Surfactant, Lung Function, and Gas Exchange"

  • Surfactant in the alveoli is a lipoprotein consisting of 90% lipid and 10% protein, with the major lipid being lecithin and the minor lipid being sphingomyelin.
  • Fetal lung maturity is indicated by a lecithin-to-sphingomyelin ratio greater than two, with surfactant produced by type two pneumocytes in the alveoli.
  • Surfactant acts as a protector by decreasing surface tension in the lungs, preventing collapse and maintaining lung shape.
  • Surfactant production begins around 20 to 24 weeks of gestation, appearing in amniotic fluid by 28 to 32 weeks, with insufficient surfactant leading to hyaline membrane disease or neonatal respiratory distress syndrome.
  • Compliance refers to the stretchability or distension capacity of the lungs, while elastance is the ability to recoil back to the original shape, with compliance and elastance being inversely related.
  • Blood flow and ventilation differ in the lung lobes, with more blood perfusion in the base and more ventilation in the base as well, affecting the ventilation-perfusion ratio.
  • Ventilation involves four liters of air per minute into the lungs, while perfusion sends five liters of blood per minute, resulting in a ventilation-perfusion ratio of 0.8 in normal conditions.
  • Pathological conditions like pulmonary embolism or foreign body obstruction can alter the ventilation-perfusion ratio, with specific values changing in different lung regions.
  • The oxygen-hemoglobin dissociation curve can shift left or right in response to exercise or resting conditions, affecting the affinity of hemoglobin for oxygen delivery to tissues.
  • Oxygen is transported mainly as oxyhemoglobin, with 97% bound to hemoglobin and 3% dissolved in plasma, while carbon dioxide is transported as bicarbonates in plasma from tissues to the lungs.

02:56:38

Understanding Hypoxia and Renal Physiology in Health

  • Stagnant hypoxia occurs in cardiogenic shock when the heart is not functioning properly, leading to oxygen not reaching tissues.
  • Cyanide poisoning inhibits complex number four in the electron transport chain, preventing oxygen utilization and water production, causing histotoxic hypoxia.
  • Four types of hypoxia include hypoxic, anemic, carbon monoxide poisoning, stagnant hypoxia in cardiogenic shock, and histotoxic hypoxia from cyanide poisoning.
  • Chemo receptors monitor oxygen and carbon dioxide levels in the body, with peripheral chemo receptors in the aortic arch and carotid sinus checking oxygen levels, and central chemo receptors in the brain monitoring carbon dioxide levels.
  • In high altitudes, increased ventilation and perfusion occur to compensate for decreased oxygen levels, leading to respiratory alkalosis and increased erythropoietin production in the kidneys.
  • Biot breathing, characterized by hyper apnea followed by apnea, is seen in spinal meningitis patients, while Kussmaul breathing, involving hyperventilation, is observed in conditions like diabetic ketoacidosis.
  • Cheyne-Stokes breathing, with gradual hyper apnea followed by hypo apnea and apnea, is seen in brain tumor patients.
  • Renal physiology includes renal blood flow of 1 to 1.2 liters per minute, with 625 ml of plasma flow and 125 ml of glomerular filtration rate per minute.
  • The glomerular filtration barrier consists of endothelial cells, glomerular basement membrane, and podocytes, with the membrane having a negative charge.
  • Nephron components include Bowman's capsule, proximal convoluted tubule reabsorbing water, descending limb concentrating urine, ascending limb reabsorbing solutes, and distal convoluted tubule reabsorbing sodium and chlorine through the sodium chloride cotransporter.

03:15:13

Renal Sodium Transport and Regulation Mechanisms

  • Sodium chloride is present in the distal convoluted tubule.
  • Loop diuretics inhibit the sodium-potassium-chloride transporter.
  • Thiazide diuretics inhibit the sodium chloride symporter.
  • Bartter syndrome is an autosomal recessive disorder affecting the sodium-potassium-chloride transporter.
  • Gitelman syndrome results from a defect in the sodium chloride symporter in the distal convoluted tubule.
  • Aldosterone acts on the collecting duct to reabsorb sodium through epithelial sodium channels.
  • Liddle syndrome occurs due to overactivity of epithelial sodium channels.
  • Medullary hyperosmolarity is created by the countercurrent multiplier system.
  • The countercurrent exchanger system helps maintain medullary hyperosmolarity.
  • The juxtaglomerular apparatus regulates the glomerular filtration rate through JG cells, macula densa, and lacis cells.
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