Lesson Notes By Weeks and Term v3 - Senior Secondary 3
Regulation of Internal Environment
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Regulation of Internal Environment
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Subject: Biology
Class: Senior Secondary 3
Term: 1st Term
Week: 1
Theme: The Organism At Work
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List the main or gansand substances in volvedin homeostasis (controlmechanism). Describe the structure and functionsof the se or gans: kidneyand liver. Name some kidneydiseases and explaintheir symptoms and effects. Name some liverdiseases and brieflyexplain the ir symptomsand effects. Discuss the remedyfor unhealthy conditionskidney and the liver. Explain whathormones are List-some endocrineglands, the ir positionsin the body and the irfunctions. State the effect of over product!on or under production of the se hormones. Identify the mammalian skin under the microscope. Draw and labelmain structures of the skin. State the functionsof the mammalian skin. State few ways to care for the skin.
liver disease. The scarred tissue replaces healthy liver cells, impeding function.
Symptoms: Fatigue, easy bruising/bleeding, jaundice, swelling in legs (edema), fluid accumulation in abdomen (ascites), confusion (hepatic encephalopathy).
Effects: Liver failure, portal hypertension, internal bleeding, liver cancer.
Remedy: Treating the underlying cause (e.g., stopping alcohol, antiviral for hepatitis), management of complications (diuretics for fluid retention), liver transplant for end-stage cirrhosis. Fatty Liver Disease (Non-alcoholic Fatty Liver Disease - NAFLD): Description: Accumulation of excess fat in liver cells not caused by alcohol. Often associated with obesity, diabetes, and high cholesterol.
Symptoms: Often asymptomatic; may include fatigue, dull ache in upper right abdomen.
Effects: Can progress to non-alcoholic steatohepatitis (NASH), cirrhosis, and liver cancer.
Remedy: Lifestyle changes (weight loss, healthy diet, regular exercise), managing underlying conditions like diabetes. 2.
4. Skin Care Hygiene: Regular bathing with mild soap to remove dirt, sweat, and dead skin cells.
Hydration: Drinking adequate water and using moisturizers to keep skin hydrated, especially in dry climates.
Sun Protection: Avoiding prolonged exposure to direct sunlight, especially during peak hours (10 am-4 pm), or using protective clothing.
Nutrition: Eating a balanced diet rich in vitamins and antioxidants.
Avoiding Harsh Chemicals: Limiting use of strong soaps, bleaching creams, or irritants that can damage the skin's natural barrier.
Prompt Treatment of Skin Conditions: Addressing cuts, infections, and allergic reactions promptly. 2.
1. Homeostasis Homeostasis is the maintenance of a relatively constant internal environment in an organism, despite fluctuations in the external environment. This internal stability is crucial for optimal enzyme activity and overall cellular function, ensuring the organism's survival. Key parameters regulated include body temperature, blood glucose levels, water balance (osmoregulation), pH, and waste product concentration. 2.
2. Main Organs and Substances Involved in Homeostasis The major organs involved in homeostatic regulation in mammals include the kidney, liver, skin, lungs, and brain (hypothalamus). Substances involved include hormones, water, salts, glucose, and waste products like urea. 2.2.
1. The Kidney Structure: The kidneys are a pair of bean-shaped, dark red organs located at the back of the abdominal cavity, one on each side of the spine.
Gross Structure: Each kidney is covered by a fibrous capsule and consists of two main regions: Cortex: The outer granular region.
Medulla: The inner striated region, containing renal pyramids.
Renal Pelvis: A funnel-shaped cavity leading into the ureter, collecting urine from the medulla.
Ureter: Tube carrying urine from the kidney to the urinary bladder.
Microscopic Structure (Nephron): The functional unit of the kidney is the nephron, numbering about a million per kidney.
Each nephron consists of: Malpighian Corpuscle (Renal Corpuscle): Composed of: Glomerulus: A tuft of capillaries where ultrafiltration occurs.
Bowman's Capsule: A cup-shaped structure surrounding the glomerulus, collecting the filtrate.
Renal Tubule: A long, convoluted tube continuous with Bowman's capsule, where selective reabsorption and tubular secretion occur.
It consists of: Proximal Convoluted Tubule (PCT) Loop of Henle (descending and ascending limbs) Distal Convoluted Tubule (DCT)
Collecting Duct: Receives filtrate from several nephrons and carries it towards the renal pelvis.
Functions:
1. Osmoregulation: Regulates water and salt balance in the body, maintaining blood volume and pressure. The Loop of Henle and collecting ducts, under the influence of ADH (Antidiuretic Hormone), are crucial here.
2. Excretion: Removes nitrogenous waste products (e.g., urea, creatinine, uric acid) from the blood, forming urine.
3. Regulation of pH: Maintains acid-base balance by excreting excess hydrogen ions and reabsorbing bicarbonate ions.
4. Hormone Production: Produces erythropoietin (stimulates red blood cell production) and renin (regulates blood pressure). It also converts Vitamin D into its active form. 2.2.
2. The Liver Structure: The liver is the largest internal organ and gland in the body, located in the upper right quadrant of the abdomen. It is dark reddish-brown, wedge-shaped, and consists primarily of two main lobes (right and left), further divided into smaller lobules.
Blood Supply: Receives blood from two sources: Hepatic Artery: Supplies oxygenated blood from the heart.
Hepatic Portal Vein: Carries nutrient-rich, deoxygenated blood from the digestive tract, spleen, and pancreas.
Bile Ducts: Collect bile produced by the liver cells (hepatocytes) and transport it to the gallbladder for storage or directly to the small intestine.
Functions:
1. Metabolic Regulation: Carbohydrate Metabolism: Regulates blood glucose levels (glycogenesis, glycogenolysis, gluconeogenesis). Converts excess glucose into glycogen for storage or fat.
Lipid Metabolism: Synthesizes cholesterol, lipoproteins, and breaks down fatty acids.
Protein Metabolism: Deaminates excess amino acids (forms urea from ammonia), synthesizes plasma proteins (e.g., albumin, clotting factors).
2. Detoxification: Filters and detoxifies harmful substances, drugs, and alcohol from the blood, converting them into less toxic forms for excretion.
3. Bile Production: Produces bile, which aids in the emulsification of fats in the small intestine, facilitating digestion and absorption.
4. Storage: Stores vitamins (A, D, E, K, B12), iron, and glycogen.
5. Heat Production: Generates significant heat through metabolic activities, contributing to body temperature regulation.
6. Immune Function: Contains Kupffer cells, specialized macrophages that phagocytose bacteria and old red blood cells. 2.2.
3. The Skin Structure: The mammalian skin is the body's largest organ.
It consists of three main layers:
1. Epidermis: The outermost layer, primarily for protection.
It includes: Stratum Corneum: Outermost layer of dead, keratinized cells, providing a tough, waterproof barrier.
Malpighian Layer (Stratum Basale): Innermost epidermal layer, containing actively dividing cells and melanocytes (produce melanin for pigment and UV protection).
2. Dermis: The middle, thicker layer, providing strength and elasticity.
Contains: * Immune Function: Contains Kupffer cells, specialized macrophages that phagocytose bacteria and old red blood cells. 2.2.
3. The Skin Structure: The mammalian skin is the body's largest organ.
It consists of three main layers:
1. Epidermis: The outermost layer, primarily for protection.
It includes: Stratum Corneum: Outermost layer of dead, keratinized cells, providing a tough, waterproof barrier.
Malpighian Layer (Stratum Basale): Innermost epidermal layer, containing actively dividing cells and melanocytes (produce melanin for pigment and UV protection).
2. Dermis: The middle, thicker layer, providing strength and elasticity.
Contains: Blood Vessels: Supply nutrients and regulate temperature.
Nerve Endings: Detect touch, pressure, pain, and temperature.
Hair Follicles: Produce hair.
Sweat Glands (Sudoriferous Glands): Produce sweat for cooling.
Sebaceous Glands: Produce sebum (oil) to lubricate skin and hair, and inhibit bacterial growth.
Connective Tissue: Collagen and elastic fibers.
3. Subcutaneous Tissue (Hypodermis): The innermost layer, primarily composed of adipose tissue (fat). Functions in insulation, energy storage, and shock absorption.
Functions:
1. Protection: Acts as a physical barrier against pathogens, UV radiation, mechanical injury, and dehydration.
2. Thermoregulation: Regulates body temperature through: Sweating: Evaporation of sweat cools the body.
Vasodilation/Vasoconstriction: Dilation of blood vessels increases heat loss; constriction reduces heat loss.
Hair Erection (Piloerection): Traps air for insulation (less significant in humans).
3. Sensation: Contains numerous nerve endings for touch, pressure, pain, and temperature detection.
4. Excretion: Excretes small amounts of salts, urea, and lactic acid through sweat.
5. Vitamin D Synthesis: Synthesizes Vitamin D upon exposure to sunlight. 2.2.
4. Hormones Definition: Hormones are chemical messengers produced by endocrine glands, secreted directly into the bloodstream, and transported to target cells or organs where they exert specific regulatory effects.
Characteristics: Produced in minute quantities. Secreted directly into the blood (ductless glands). Transported by blood to distant target organs. Have specific physiological effects on target cells. Their action is typically slower but longer-lasting than nerve impulses. * Their production is often regulated by feedback mechanisms. 2.2.
5. Endocrine Glands, Hormones, and Their Effects | Endocrine Gland | Location | Hormones Secreted | Functions | Effects of Overproduction (Hyper-) | Effects of Underproduction (Hypo-) | | :--------------- | :------- | :---------------- | :-------- | :--------------------------------- | :--------------------------------- | | Pituitary Gland | Base of brain (hypothalamus attached) | Growth Hormone (GH) | Promotes growth of bones and tissues. | Gigantism (children), Acromegaly (adults) | Dwarfism (children), Pituitary cachexia (adults) | | | | Thyroid Stimulating Hormone (TSH) | Stimulates thyroid gland. | Hyperthyroidism (secondary) | Hypothyroidism (secondary) | | | | Adrenocorticotropic Hormone (ACTH) | Stimulates adrenal cortex. | Cushing's disease (secondary) | Addison's disease (secondary) | | | | Follicle Stimulating Hormone (FSH) | Ovarian follicle development, spermatogenesis. | Multiple births (females) | Infertility | | | | Luteinizing Hormone (LH) | Ovulation, corpus luteum formation, testosterone production. | - | Infertility | | | | Prolactin | Milk production in mammary glands. | Galactorrhea (inappropriate milk production) | Poor milk production | | | | Antidiuretic Hormone (ADH) / Vasopressin | Water reabsorption in kidneys. | Syndrome of Inappropriate ADH (SIADH) - water retention | Diabetes Insipidus (excessive urination, dehydration) | | | | Oxytocin | Uterine contractions during childbirth, milk ejection. | - | Prolonged labor, poor milk ejection | | Thyroid Gland | Anterior neck, below larynx | Thyroxine (T4), Triiodothyronine (T3) | Regulates metabolism, growth, development. | Hyperthyroidism (e.g., Grave's disease): weight loss, tremors, heat intolerance, bulging eyes. | Hypothyroidism (e.g., Myxedema, Cretinism): weight gain, fatigue, cold intolerance, slow heart rate, intellectual disability (in children). | | Pancreas (Islets of Langerhans) | Behind the stomach | Insulin | Lowers blood glucose by promoting glucose uptake. | Hypoglycemia (low blood sugar) | Diabetes Mellitus (Type 1 & 2): high blood glucose, frequent urination, thirst, weight loss. | | | | Glucagon | Raises blood glucose by stimulating glycogenolysis. | Hyperglycemia | Hypoglycemia | | Adrenal Gland | On top of kidneys | Adrenaline (Epinephrine) / Noradrenaline (Norepinephrine) (Medulla) | "Fight or flight" response: increases heart rate, blood pressure, glucose. | Pheochromocytoma: high blood pressure, palpitations, sweating. (in children). | | Pancreas (Islets of Langerhans) | Behind the stomach | Insulin | Lowers blood glucose by promoting glucose uptake. | Hypoglycemia (low blood sugar) | Diabetes Mellitus (Type 1 & 2): high blood glucose, frequent urination, thirst, weight loss. | | | | Glucagon | Raises blood glucose by stimulating glycogenolysis. | Hyperglycemia | Hypoglycemia | | Adrenal Gland | On top of kidneys | Adrenaline (Epinephrine) / Noradrenaline (Norepinephrine) (Medulla) | "Fight or flight" response: increases heart rate, blood pressure, glucose. | Pheochromocytoma: high blood pressure, palpitations, sweating. | - | | | | Aldosterone (Cortex) | Regulates sodium and potassium balance (water balance). | Conn's Syndrome: hypertension, low potassium. | Addison's Disease: low blood pressure, dehydration, high potassium. | | | | Cortisol (Cortex) | Stress response, anti-inflammatory, glucose metabolism. | Cushing's Syndrome: moon face, obesity, muscle weakness, thin skin. | Addison's Disease: fatigue, weight loss, low blood pressure, skin hyperpigmentation. | | Gonads | Testes (males) - Scrotum | Testosterone | Male secondary sexual characteristics, sperm production. | - | Impotence, reduced libido, poor muscle development. | | | Ovaries (females) - Pelvic cavity | Estrogen | Female secondary sexual characteristics, menstrual cycle. | - | Irregular periods, osteoporosis, infertility. | | | | Progesterone | Prepares uterus for pregnancy, maintains pregnancy. | - | Miscarriage, menstrual irregularities. | 2.
3. Diseases of the Kidney and Liver, Symptoms, Effects, and Remedies 2.3.
1. Kidney Diseases Renal (Kidney)
Failure: Description: Kidneys lose their ability to remove waste products and maintain fluid and electrolyte balance. Can be acute (sudden) or chronic (gradual).
Symptoms: Swelling (edema) in legs/ankles/face, reduced urine output, fatigue, nausea, shortness of breath, confusion.
Effects: Accumulation of toxins (urea, creatinine) in blood, fluid overload, electrolyte imbalance (e.g., high potassium), anemia, bone disease, hypertension.
Remedy: Dialysis: Artificial filtering of blood (hemodialysis or peritoneal dialysis). Common in Nigeria for managing chronic failure.
Kidney Transplant: Surgical replacement of a diseased kidney with a healthy donor kidney.
Dietary Modifications: Limiting protein, sodium, potassium, and phosphorus intake.
Kidney Stones (Nephrolithiasis): Description: Hard deposits of minerals and salts that form inside the kidneys.
Symptoms: Severe pain in the back/side (colic), pain radiating to the groin, blood in urine, nausea, vomiting, frequent urination.
Effects: Blockage of urine flow, kidney damage, recurrent infections.
Remedy: Pain medication, increased fluid intake, medication to help pass stones, lithotripsy (shock waves to break stones), surgery.
Glomerulonephritis: Description: Inflammation of the glomeruli (tiny filters) in the kidneys. Can be acute or chronic. Often caused by infections (e.g., strep throat) or autoimmune diseases.
Symptoms: Blood in urine (hematuria), foamy urine (proteinuria), swelling, high blood pressure.
Effects: Kidney damage, potential progression to kidney failure.
Remedy: Medications (e.g., antibiotics, corticosteroids), blood pressure control, dialysis in severe cases. 2.3.
2. Liver Diseases Hepatitis (Viral Hepatitis A, B, C): Description: Inflammation of the liver, primarily caused by viral infections (Hepatitis A, B, C, D, E). Hepatitis B and C are particularly chronic and prevalent in Nigeria.
Symptoms: Jaundice (yellow skin/eyes), fatigue, nausea, vomiting, abdominal pain (especially upper right quadrant), dark urine, pale stools. Many infected people, especially with Hep B/C, may be asymptomatic for years.
Effects: Acute liver failure, chronic hepatitis, cirrhosis, liver cancer (hepatocellular carcinoma).
Remedy: Hepatitis A: Self-limiting, rest, hydration.
Hepatitis B & C: Antiviral medications, regular monitoring. Vaccination is crucial for prevention (especially Hepatitis B).
Cirrhosis: Description: Severe scarring of the liver, typically caused by chronic liver diseases like chronic hepatitis, alcoholism, or non-alcoholic fatty liver disease. The scarred tissue replaces healthy liver cells, impeding function.
Symptoms: Fatigue, easy bruising/bleeding, jaundice, swelling in legs (edema), fluid accumulation in abdomen (ascites), confusion (hepatic encephalopathy).
Effects: Liver failure, portal hypertension, internal bleeding, liver cancer.
Remedy: Treating the underlying cause (e.g., stopping alcohol, antiviral for hepatitis), management of complications (diuretics for fluid retention), liver transplant for end-stage cirrhosis. Fatty Liver Disease (Non-alcoholic Fatty Liver Disease - NAFLD): Description: Accumulation of excess fat in liver cells not caused by alcohol. Often associated with obesity, diabetes, and
Health Education and Disease Prevention: Understanding the functions of the kidney and liver directly informs public health campaigns in Nigeria regarding common diseases. For example, knowledge of kidney function can be integrated into discussions about managing hypertension (a risk factor for kidney disease), responsible drug use, and the importance of hydration. Liver function knowledge is vital for understanding the dangers of excessive alcohol consumption (leading to cirrhosis), safe food handling (preventing Hepatitis A), and the importance of Hepatitis B vaccination, which is crucial for reducing liver cancer rates in Nigeria. Environmental Adaptation and Personal Hygiene: The skin's role in thermoregulation is highly relevant in Nigeria's tropical climate. Students can apply this knowledge to understand why they sweat profusely during hot weather or strenuous activities and how to stay cool and hydrated. The lesson also reinforces the importance of personal hygiene (regular bathing) and sun protection for maintaining healthy skin, guarding against infections, and preventing skin damage, particularly with the prevalent use of various skin products in local markets. Diabetes and Hormonal Imbalance Management: Diabetes mellitus (linked to insulin deficiency/resistance from the pancreas) is a growing health concern in Nigeria. This lesson provides fundamental knowledge about the role of insulin and glucagon, enabling students to grasp the physiological basis of diabetes. This understanding can empower them to advocate for healthy lifestyle choices, recognize symptoms early, and appreciate the importance of adherence to medical advice for managing the condition within their families and communities.