Shyam Sundar
Showing posts with label PHYSIOLOGY. Show all posts
Showing posts with label PHYSIOLOGY. Show all posts
Monday, 31 March 2025
Friday, 25 October 2024
Cardiovascular Physiology MBBS basic science MCQ , CEE ,Nepal
PHYSIOLOGY
MBBS Basic Science: Cardiovascular System Overview
Structure of the Cardiovascular System
The cardiovascular system consists of the heart, blood vessels, and blood. The heart is a muscular organ located in the thoracic cavity, functioning as a pump to circulate blood throughout the body. It is divided into four chambers: two atria and two ventricles. The right side of the heart pumps deoxygenated blood to the lungs via the pulmonary circulation, while the left side pumps oxygenated blood to the rest of the body through systemic circulation.
Circulation of Blood
Blood circulates through two primary pathways: pulmonary and systemic circulation. Pulmonary circulation carries deoxygenated blood from the right ventricle to the lungs, where gas exchange occurs, and oxygenated blood returns to the left atrium. Systemic circulation moves oxygen-rich blood from the left ventricle to the entire body, supplying tissues with oxygen and nutrients, and returns deoxygenated blood to the right atrium.
Heart Function and Electrical Conduction
The heart functions as a pump through a cycle of contraction (systole) and relaxation (diastole). Electrical impulses generated by the sinoatrial (SA) node initiate heart contractions, spreading through the atria to the atrioventricular (AV) node, and then down the bundle of His and Purkinje fibers, triggering ventricular contraction. This electrical system ensures the coordinated contraction of the heart, maintaining efficient blood flow.
Blood Vessels and Blood Pressure
Blood vessels form a network of arteries, veins, and capillaries that transport blood throughout the body. Arteries carry oxygenated blood away from the heart, while veins return deoxygenated blood back to the heart. Capillaries, the smallest blood vessels, facilitate nutrient and gas exchange between blood and tissues. Blood pressure, the force exerted by circulating blood on the walls of blood vessels, is regulated by cardiac output, blood volume, and resistance within the vessels.
Regulation of the Cardiovascular System
The cardiovascular system is regulated by multiple mechanisms to maintain homeostasis. The autonomic nervous system controls heart rate and vessel diameter, while hormones like adrenaline and angiotensin influence blood pressure and cardiac function. Baroreceptors in major arteries detect changes in blood pressure and trigger reflex responses to stabilize circulation.
Clinical Significance
A comprehensive understanding of the cardiovascular system is essential for diagnosing and managing conditions like hypertension, coronary artery disease, heart failure, and arrhythmias. The MBBS curriculum emphasizes the application of cardiovascular physiology in clinical settings to ensure future physicians can address a range of heart and vascular disorders.
Wednesday, 23 October 2024
PHYSIOLOGY G.I chapter wise MBBS basic science MCQ ,CEE ,Nepal
PHYSIOLOGY
MBBS Basic Science: Gastrointestinal System Overview
Structure of the Gastrointestinal System
The gastrointestinal (GI) system consists of the alimentary canal, which includes the mouth, esophagus, stomach, small intestine, and large intestine, along with associated glands such as the liver, pancreas, and gallbladder. Its primary function is to digest food, absorb nutrients, and eliminate waste. The system is organized to ensure the breakdown of food into smaller components and the absorption of nutrients into the bloodstream.
Digestion and Absorption
Digestion begins in the mouth, where food is broken down mechanically by chewing and chemically by enzymes in saliva. The food bolus is then transported through the esophagus to the stomach via peristalsis. In the stomach, gastric juices containing hydrochloric acid and pepsin further break down proteins. The partially digested food, now called chyme, moves into the small intestine, where most digestion and absorption occur.
The small intestine is divided into three sections: the duodenum, jejunum, and ileum. Enzymes from the pancreas and bile from the liver aid in digesting fats, proteins, and carbohydrates. The absorbed nutrients pass through the intestinal walls into the bloodstream, while undigested material moves into the large intestine for water reabsorption and eventual elimination.
Functions of the Liver, Gallbladder, and Pancreas
The liver is a vital organ in digestion, producing bile which helps emulsify fats in the small intestine. It also detoxifies substances and metabolizes nutrients. The gallbladder stores bile and releases it into the duodenum as needed. The pancreas plays a dual role: producing digestive enzymes to break down carbohydrates, proteins, and fats, and secreting insulin and glucagon to regulate blood sugar levels.
Regulation of the GI System
The gastrointestinal system is regulated by both the nervous and hormonal systems. The enteric nervous system, sometimes referred to as the "second brain," coordinates motility and secretions within the GI tract. The autonomic nervous system, including the sympathetic and parasympathetic divisions, also modulates GI activity. Hormones such as gastrin, secretin, and cholecystokinin (CCK) control various digestive processes, including acid secretion, enzyme release, and bile production.
Clinical Significance
Knowledge of the GI system is critical for diagnosing and managing disorders such as gastroesophageal reflux disease (GERD), peptic ulcers, inflammatory bowel disease (IBD), and liver diseases. The MBBS curriculum emphasizes the integration of gastrointestinal physiology with clinical practice, enabling students to effectively diagnose and treat various GI conditions.
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