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Semester 1: Physiological Aspects of Nutrition
Digestive system: Structure, functions, gastrointestinal secretions, enzymes, prebiotics and probiotics, regulation of food intake
Digestive system: Structure, functions, gastrointestinal secretions, enzymes, prebiotics and probiotics, regulation of food intake
Structure of the Digestive System
The human digestive system consists of the alimentary canal and accessory organs. The alimentary canal includes the mouth, esophagus, stomach, small intestine, large intestine, rectum, and anus. Accessory organs such as the liver, pancreas, and gallbladder play important roles in digestion.
Functions of the Digestive System
The primary functions of the digestive system are to break down food into nutrients, absorb those nutrients into the bloodstream, and eliminate waste. It also plays a role in the regulation of water, electrolytes, and the detoxification of substances.
Gastrointestinal Secretions
Gastrointestinal secretions include saliva, gastric juice, bile, and pancreatic juice. Saliva aids in the breakdown of carbohydrates, gastric juice provides acidity for protein digestion, bile emulsifies fats, and pancreatic juice contains enzymes that further digest carbohydrates, proteins, and fats.
Enzymes in Digestion
Digestive enzymes are crucial for breaking down macronutrients. Key enzymes include amylase for carbohydrates, pepsin for proteins, and lipase for fats. These enzymes are produced by various organs including the salivary glands, stomach, pancreas, and small intestine.
Prebiotics and Probiotics
Prebiotics are non-digestible fibers that promote the growth of beneficial bacteria in the gut. Probiotics are live microorganisms that provide health benefits when consumed. Both play a crucial role in maintaining gut health and enhancing immune function.
Regulation of Food Intake
Food intake is regulated by a complex interplay of physiological signals from the digestive system and brain. Hormones such as ghrelin and leptin play key roles in hunger and satiety signaling. Neural pathways also contribute to the control of appetite and digestion.
Liver: Structure and functions
Liver: Structure and Functions
Anatomy of the Liver
The liver is a large, reddish-brown organ located in the upper right quadrant of the abdomen. It is divided into two main lobes, the right and left lobes, which are further divided into smaller lobes called lobules. The functional units of the liver are the hepatocytes, which are involved in various metabolic processes.
Blood Supply
The liver receives blood from two sources: the hepatic artery and the portal vein. The hepatic artery supplies oxygen-rich blood, while the portal vein carries nutrient-rich blood from the gastrointestinal tract. This dual blood supply is essential for liver function.
Functions of the Liver
The liver performs numerous functions, including protein synthesis, detoxification, bile production, and metabolism of carbohydrates, fats, and proteins. It plays a crucial role in maintaining homeostasis in the body.
Metabolic Functions
The liver is involved in carbohydrate metabolism through gluconeogenesis and glycogen storage. It metabolizes lipids through fatty acid oxidation and lipoprotein synthesis. Protein metabolism includes the urea cycle and synthesis of plasma proteins like albumin.
Detoxification
The liver detoxifies harmful substances by converting them into less harmful forms. This includes the metabolism of drugs, alcohol, and toxins. Cytochrome P450 enzymes play a significant role in this process.
Bile Production
The liver produces bile, which is essential for digestion and absorption of fats in the small intestine. Bile is stored in the gallbladder and released into the intestine when needed.
Liver Disorders
Common liver disorders include hepatitis, cirrhosis, and fatty liver disease. These conditions can impact liver function and overall health, highlighting the importance of maintaining liver health.
Respiratory system: Structure of lungs, gaseous exchange, oxygen and carbon dioxide transport
Respiratory system: Structure of lungs, gaseous exchange, oxygen and carbon dioxide transport
Structure of Lungs
The lungs are a pair of spongy, air-filled organs situated on either side of the chest (thorax). They are comprised of various structures including the bronchi, bronchioles, alveoli, and pleura. The bronchi branch off into smaller tubes (bronchioles) leading to tiny air sacs called alveoli where gas exchange occurs. The lungs are protected by the rib cage and are lined by a smooth membrane called pleura.
Gaseous Exchange
Gaseous exchange occurs in the alveoli, where oxygen from inhaled air passes through the alveolar walls into the blood and carbon dioxide from the blood is expelled into the alveoli to be exhaled. This process involves diffusion, driven by the concentration gradients of oxygen and carbon dioxide. The large surface area of the alveoli and their thin walls facilitate efficient gas exchange.
Oxygen Transport
Once oxygen enters the bloodstream, it binds to hemoglobin molecules in red blood cells. About 98.5% of oxygen is carried in this form, while the remaining 1.5% is dissolved in plasma. Oxygen-rich blood is then transported from the lungs to the heart and subsequently distributed to tissues throughout the body.
Carbon Dioxide Transport
Carbon dioxide is transported in the blood in three forms: dissolved in plasma (about 7%), bound to hemoglobin (approximately 23%), and as bicarbonate ions (about 70%). Once carbon dioxide reaches the lungs, it diffuses from the blood into the alveoli to be exhaled.
Nervous system: Brain and spinal cord structure, neuron function, neurotransmitters, blood brain barrier, hypothalamus
Nervous system: Brain and spinal cord structure, neuron function, neurotransmitters, blood-brain barrier, hypothalamus
Brain and Spinal Cord Structure
The brain is the central organ of the nervous system, consisting of various regions including the cerebrum, cerebellum, and brainstem, each responsible for different functions. The spinal cord connects the brain to the peripheral nervous system and is divided into cervical, thoracic, lumbar, sacral, and coccygeal regions. Together, the brain and spinal cord make up the central nervous system, which processes and transmits information throughout the body.
Neuron Function
Neurons are specialized cells that transmit information via electrical impulses. They consist of three main parts: the cell body, dendrites, and axon. Dendrites receive signals from other neurons, the cell body processes these signals, and the axon transmits impulses to other neurons or to muscles. Neurons communicate through synapses, where neurotransmitters are released.
Neurotransmitters
Neurotransmitters are chemical messengers that transmit signals across synapses from one neuron to another. Common neurotransmitters include dopamine, serotonin, and acetylcholine, each playing vital roles in mood regulation, motor control, and other cognitive functions. The balance of neurotransmitters is crucial for mental health and overall neurological function.
Blood-Brain Barrier
The blood-brain barrier is a selective permeability barrier that protects the brain from harmful substances in the bloodstream while allowing essential nutrients to pass through. It is formed by tightly packed endothelial cells of brain capillaries and plays a crucial role in maintaining the brain's stable environment.
Hypothalamus
The hypothalamus is a small region of the brain that plays a major role in regulating homeostasis. It controls various functions such as temperature regulation, hunger, thirst, sleep, and circadian rhythms. The hypothalamus also links the nervous system to the endocrine system by controlling the pituitary gland, influencing hormonal balance.
Musculoskeletal system: Bone structure, muscle contraction physiology
Bone Structure
The human skeleton is composed of 206 bones that provide support, protection, and a framework for the body. Bones are classified into two main types: compact bone and spongy bone. Compact bone is dense and forms the outer layer of bones, while spongy bone consists of a network of trabeculae and is found inside bones. Bone tissue is made up of cells such as osteocytes, osteoblasts, and osteoclasts, and is rich in minerals, particularly calcium and phosphorus.
Physiology of Muscle Contraction
Muscle contraction is a complex physiological process that involves the interaction of myosin and actin filaments within muscle fibers. The process is initiated by the release of calcium ions from the sarcoplasmic reticulum, which binds to troponin, leading to the exposure of binding sites on actin filaments. ATP is required for the 'power stroke' of myosin heads, causing muscle fibers to shorten and contract. The cycle of contraction and relaxation is regulated by neural stimulation and biochemical signals.
Relationship Between Nutrition and Musculoskeletal Health
Nutrition plays a critical role in supporting the musculoskeletal system. Essential nutrients, including proteins, vitamins (such as vitamin D), and minerals (such as calcium), are important for bone health and muscle function. Adequate protein intake is necessary for muscle repair and growth, while calcium and vitamin D are vital for maintaining bone density and strength.
Impact of Exercise on Bone and Muscle Physiology
Regular physical activity is crucial for maintaining the health of bones and muscles. Weight-bearing exercises stimulate bone remodeling, enhancing bone density and strength. Resistance training directly affects muscle hypertrophy by promoting the growth of muscle fibers. Additionally, exercise improves balance and coordination, reducing the risk of falls and fractures.
Cardiovascular system: Blood composition, heart and blood vessels, cardiac output regulation, heart failure, hypertension
Cardiovascular system
Blood composition
The blood is primarily composed of plasma, red blood cells, white blood cells, and platelets. Plasma constitutes about 55% of total blood volume and contains water, electrolytes, proteins, hormones, and waste products. Red blood cells are responsible for oxygen transport, white blood cells play a key role in immune response, and platelets are crucial for clotting processes.
Heart structure and function
The heart is a muscular organ that pumps blood throughout the body. It consists of four chambers: the right atrium and ventricle, and the left atrium and ventricle. The heart valves ensure unidirectional blood flow. The cardiac muscle contracts rhythmically to maintain blood circulation.
Blood vessels
Blood vessels consist of arteries, veins, and capillaries. Arteries carry oxygenated blood away from the heart, while veins return deoxygenated blood to the heart. Capillaries facilitate the exchange of nutrients, gases, and waste products between blood and tissues.
Cardiac output regulation
Cardiac output is the volume of blood the heart pumps per minute, influenced by heart rate and stroke volume. Regulation involves neural and hormonal mechanisms, including the autonomic nervous system and hormones like adrenaline. Factors such as physical activity and body position also impact cardiac output.
Heart failure
Heart failure is a condition in which the heart cannot pump sufficient blood to meet the body's needs. Symptoms include fatigue, shortness of breath, and fluid retention. It can result from coronary artery disease, hypertension, or previous heart attacks.
Hypertension
Hypertension, or high blood pressure, is a chronic condition that can lead to severe health issues such as heart disease and stroke. It is often termed the 'silent killer' due to the lack of observable symptoms. Risk factors include obesity, poor diet, lack of physical activity, and genetic predisposition.
Excretory system: Kidney structure, nephron, urine formation, micturition
Excretory system: Kidney structure, nephron, urine formation, micturition
Kidney Structure
The kidneys are bean-shaped organs located on either side of the spine. They are responsible for filtering blood, removing waste, and balancing body fluids. Each kidney consists of an outer cortex, an inner medulla, and a renal pelvis. The functional unit of the kidney is the nephron, and each kidney contains approximately one million nephrons.
Nephron
The nephron is the basic structural and functional unit of the kidney. It consists of a renal corpuscle (including the glomerulus and Bowman's capsule) and a renal tubule (including the proximal tubule, loop of Henle, distal tubule, and collecting duct). The nephron is responsible for filtering blood and forming urine through processes such as filtration, reabsorption, and secretion.
Urine Formation
Urine formation occurs in three main stages: filtration, reabsorption, and secretion. Filtration takes place in the glomerulus where blood plasma is filtered into Bowman's capsule. Reabsorption occurs in the renal tubule where essential nutrients and water are reabsorbed back into the bloodstream. Secretion involves the removal of additional wastes from the blood into the urine.
Micturition
Micturition, or urination, is the process of expelling urine from the bladder. It involves the contraction of the bladder muscles and the relaxation of the sphincters. The micturition reflex is controlled by the nervous system and is influenced by various factors including bladder fullness and external stimuli. The coordination between voluntary and involuntary muscle control is essential for normal micturition.
Endocrine system: Hormones, regulation, pituitary, thyroid, adrenal, pancreas, parathyroid glands, insulin functions and deficiency
Endocrine system: Hormones, regulation, pituitary, thyroid, adrenal, pancreas, parathyroid glands, insulin functions and deficiency
Endocrine System Overview
The endocrine system is a complex network of glands that produce and secrete hormones. These hormones regulate various physiological processes, including metabolism, growth, reproduction, and mood.
Hormones and Their Functions
Hormones are chemical messengers that travel through the bloodstream to tissues and organs to regulate functions. Key hormones include insulin, glucagon, cortisol, thyroid hormones, and sex hormones.
Pituitary Gland
The pituitary gland, known as the master gland, controls other endocrine glands and regulates growth, metabolism, and reproductive processes. It secretes hormones like growth hormone, ACTH, and thyroid-stimulating hormone.
Thyroid Gland
The thyroid gland produces hormones such as thyroxine (T4) and triiodothyronine (T3), which regulate metabolism, energy levels, and overall growth and development.
Adrenal Glands
The adrenal glands produce corticosteroids such as cortisol and adrenaline. These hormones help manage stress, inflammation, and blood pressure, and regulate metabolism.
Pancreas and Insulin Functions
The pancreas has both endocrine and exocrine functions. It produces insulin, which lowers blood glucose levels, and glucagon, which increases blood glucose levels, playing a crucial role in glucose metabolism.
Parathyroid Glands
The parathyroid glands regulate calcium levels in the blood through the secretion of parathyroid hormone (PTH), which increases calcium levels by mobilizing it from bones and promoting intestinal absorption.
Insulin Deficiency
Insulin deficiency can lead to diabetes mellitus, characterized by high blood sugar levels. Symptoms may include frequent urination, increased thirst, fatigue, and complications can affect the heart, kidneys, and vision.
Regulation of Hormones
Hormone regulation involves feedback mechanisms, primarily negative feedback loops, where the output of a system suppresses or inhibits its initiation. For example, high levels of thyroid hormones inhibit stimulating hormones from the pituitary.
Reproductive system: Ovaries, hormones, menstrual cycle, pregnancy changes, testes, testosterone
Ovaries
Ovaries are the female reproductive organs responsible for producing ova and hormones such as estrogen and progesterone. They play a crucial role in regulating the menstrual cycle and fertility.
Hormones
Hormones produced by the ovaries, primarily estrogen and progesterone, are essential for regulating the menstrual cycle, ovulation, and maintaining pregnancy. They also influence secondary sexual characteristics and overall reproductive health.
Menstrual Cycle
The menstrual cycle involves a series of physiological changes that prepare the body for potential pregnancy. It typically lasts about 28 days and is divided into phases: follicular phase, ovulation, lutheal phase, and menstruation.
Pregnancy Changes
During pregnancy, the body undergoes numerous changes, including hormonal fluctuations, physical adaptations, and nutritional needs that support fetal development. Hormones like hCG, progesterone, and estrogen increase significantly.
Testes
Testes are the male reproductive organs responsible for producing sperm and hormones, primarily testosterone. They are essential for male fertility and the development of male secondary sexual characteristics.
Testosterone
Testosterone is the primary male sex hormone, crucial for developing male reproductive tissues and promoting secondary sexual characteristics such as muscle and bone mass. It also plays a role in libido and overall health.
