Nutrients: Nutrients are substances in food that provide energy and essential elements necessary for the growth, maintenance, and repair of body tissues.
Roles:
- Provide Energy: Nutrients, particularly carbohydrates and fats, supply energy necessary for daily activities, including physical exertion and metabolic functions.
- Support Growth and Development: Essential nutrients like proteins and certain fats are crucial for the growth of tissues, especially during childhood, adolescence, and pregnancy.
- Maintain and Repair Body Tissues: Nutrients contribute to the ongoing repair of tissues, organs, and muscles, ensuring the body functions optimally.
- Regulate Bodily Functions and Processes: Nutrients help regulate physiological processes such as hormone production, nerve transmission, and enzyme activity, which are vital for homeostasis.
- Strengthen the Immune System: Certain vitamins and minerals, such as vitamin C and zinc, play a critical role in immune function, helping the body defend against pathogens.
- Facilitate Metabolic Processes: Nutrients are involved in metabolic pathways, converting food into energy, supporting various biochemical reactions necessary for life.
Human Nutrition: The science of how organisms obtain and utilize nutrients from food, encompassing various processes from consumption to metabolism.
Processes:
- Ingestion: The act of consuming food and liquids, which is the first step in human nutrition.
- Digestion: The mechanical and chemical breakdown of food into smaller, absorbable nutrients, involving enzymes and digestive juices.
- Absorption: Nutrients are absorbed primarily in the small intestine and enter the bloodstream, where they are transported to cells.
- Metabolism: The biochemical processes that convert nutrients into energy, support growth, and repair tissues, including both catabolic (breaking down) and anabolic (building up) reactions.
- Excretion: The removal of waste products from the body, which is essential for eliminating toxins and maintaining health.
Significance:
- Supports Overall Growth and Development: Proper nutrition is essential for physical and cognitive development, especially in children and adolescents.
- Maintains Bodily Functions: Adequate nutrient intake ensures all body systems function correctly, supporting health and well-being.
- Prevents Nutrient Deficiencies and Related Diseases: A balanced diet helps avoid deficiencies that can lead to health issues such as scurvy or anemia.
- Enhances Physical and Mental Performance: Good nutrition boosts energy levels, concentration, and overall performance in daily activities.
- Promotes Longevity and Quality of Life: A nutritious diet is linked to a lower risk of chronic diseases, contributing to a longer, healthier life.
Definition: Mechanical digestion involves physical processes that break down food into smaller particles, thereby increasing its surface area for enzymatic action. This process begins in the mouth and continues throughout the digestive tract.
Importance:
- Begins in the mouth: Mechanical digestion starts with mastication (chewing), where teeth break food into manageable pieces.
- Mastication: This physical breakdown increases the surface area, allowing enzymes to act more effectively.
- Mixing: In the mouth, food is mixed with saliva, which contains enzymes like salivary amylase that initiate the breakdown of carbohydrates.
- Peristalsis: Rhythmic muscular contractions move food through the digestive tract, ensuring it progresses to various organs for further digestion.
- Preparation for chemical digestion: Mechanical digestion increases the surface area of food particles, which is crucial for efficient chemical digestion in the stomach and small intestine.
- Enhances enzymatic breakdown: By reducing food size, mechanical digestion maximizes the effectiveness of enzymes and promotes better nutrient absorption in the intestines.
Definition: Peristalsis involves rhythmic muscular contractions that propel food through the digestive tract.
Function:
- Movement from esophagus to stomach: Peristalsis begins in the esophagus, pushing the bolus of food toward the stomach.
- Continuous throughout the digestive tract: This involuntary process continues from the esophagus through the stomach and into the intestines.
- Mixes and propels food: Peristaltic waves mix food with digestive juices and propel it along the digestive tract, enhancing digestion and absorption.
- Ensures continuous movement: The coordinated contractions ensure that food moves efficiently, preventing stagnation and promoting timely digestion.
- Facilitates nutrient absorption: By continuously moving food through the intestines, peristalsis aids in mixing food with enzymes and bile, maximizing nutrient absorption.
- Regulates digestive rhythm: It helps maintain a rhythm in the digestive process, ensuring that food is processed in an orderly manner.
Gastric Glands: The gastric glands in the stomach lining secrete gastric juice, which is crucial for digestion.
Hydrochloric Acid (HCl):
- Lowers stomach pH: The secretion of HCl creates a highly acidic environment in the stomach, which is essential for the activation of digestive enzymes.
- Activates pepsin: HCl converts pepsinogen (an inactive enzyme) into pepsin, which begins the process of protein digestion.
- Denatures proteins: The acidic environment denatures proteins, unraveling their complex structures and making them more accessible to enzymatic action.
Pepsin:
- Breaks down proteins: Pepsin is an enzyme that hydrolyzes proteins into smaller peptides, facilitating their further digestion in the small intestine.
Chyme Formation:
- Mixture of food and gastric juice: The partially digested food, now called chyme, is mixed with gastric juice, transforming it into a semi-liquid mass.
Mechanical Churning:
- Physical breakdown: The stomach muscles contract, churning the chyme and further breaking it down, ensuring even mixing with digestive juices.
Preparation for Small Intestine:
- Entry of chyme: Once digestion is sufficiently completed, chyme is gradually released into the small intestine, where further digestion and nutrient absorption occur.
Bile Production: Bile is produced by the liver and stored in the gallbladder, playing a crucial role in fat digestion.
Emulsification: Bile contains bile salts that emulsify large fat globules into smaller droplets, increasing their surface area for enzymatic action.
Increases Surface Area: By breaking down fats into smaller droplets, bile enhances the action of lipase, the enzyme responsible for fat digestion.
Neutralizes Acidity: Bile helps neutralize stomach acid as chyme enters the small intestine, creating a suitable environment for the action of pancreatic enzymes.
Aids in Absorption: Bile facilitates the absorption of fatty acids and fat-soluble vitamins (A, D, E, and K) in the small intestine by forming micelles that transport these nutrients across the intestinal membrane.
Elimination of Waste: Bile plays a role in the elimination of bilirubin (a breakdown product of hemoglobin) and excess cholesterol from the body, aiding in waste management.
Definition: Glycolysis is the metabolic pathway that converts glucose into pyruvate, producing energy in the form of ATP.
Importance:
- Produces ATP: Glycolysis generates a net gain of 2 ATP molecules per glucose molecule, providing immediate energy for cellular activities.
- Occurs in the cytoplasm: This pathway takes place in the cytoplasm of cells, allowing for rapid energy production without the need for oxygen.
- Generates NADH: Glycolysis produces NADH, an important electron carrier that is used in further energy production processes, such as the electron transport chain.
- Intermediates for other pathways: The end products of glycolysis, especially pyruvate, can enter the citric acid cycle or be converted into lactate, linking glycolysis to aerobic and anaerobic respiration.
- Regulatory steps: Key enzymes in glycolysis (like phosphofructokinase) regulate the pathway, making it responsive to the energy needs of the cell.
- Initiates glucose metabolism: Glycolysis is the first step in the metabolism of carbohydrates, setting the stage for further oxidation in aerobic respiration or fermentation.
Overview: The citric acid cycle (Krebs cycle) is a series of enzymatic reactions that takes place in the mitochondrial matrix, playing a critical role in aerobic respiration.
Key Functions:
- Oxidation of Acetyl-CoA: The cycle begins with the oxidation of acetyl-CoA, derived from carbohydrates, fats, and proteins, generating energy-rich molecules.
- Produces NADH and FADH2: Each turn of the cycle produces three NADH and one FADH2, which are essential electron carriers for the electron transport chain.
- Generates GTP or ATP: The cycle also produces one molecule of GTP (or ATP) per turn, contributing to the cell's energy currency.
- Carbon Dioxide Production: The cycle releases carbon dioxide as a waste product, which is exhaled by organisms.
- Precursor for biosynthesis: Intermediates of the citric acid cycle serve as precursors for the synthesis of amino acids, nucleotides, and other essential biomolecules.
- Connects various metabolic pathways: The citric acid cycle integrates carbohydrate, fat, and protein metabolism, making it central to the overall energy production process.
Definition: Oxidative phosphorylation is the final stage of cellular respiration, occurring in the inner mitochondrial membrane, where ATP is produced using energy from the electron transport chain.
Process:
- Electron transport chain (ETC): NADH and FADH2 donate electrons to the ETC, which consists of a series of protein complexes that facilitate the transfer of electrons.
- Proton gradient formation: As electrons move through the chain, protons (H⁺ ions) are pumped from the mitochondrial matrix into the intermembrane space, creating a proton gradient.
- Chemiosmosis: Protons flow back into the matrix through ATP synthase, a protein complex that synthesizes ATP from ADP and inorganic phosphate (Pi).
- Oxygen as the final electron acceptor: Oxygen, the final electron acceptor, combines with electrons and protons to form water, a byproduct of cellular respiration.
Significance:
- High ATP yield: Oxidative phosphorylation generates a substantial amount of ATP, approximately 28-30 ATP molecules per glucose molecule, making it the most efficient energy-producing process in cellular respiration.
- Dependency on oxygen: It requires oxygen, linking aerobic respiration to the need for oxygen in energy production.
- Heat production: The process also contributes to thermogenesis, helping maintain body temperature in warm-blooded organisms.
- Regulatory role: The availability of oxygen and ADP regulates oxidative phosphorylation, allowing cells to adjust energy production based on metabolic needs.
- Role in metabolism: It connects to other metabolic pathways, including fatty acid oxidation and the citric acid cycle, allowing for the integration of various energy sources.
- Cellular efficiency: By utilizing the energy from electron transfer, oxidative phosphorylation maximizes ATP production, ensuring cells have sufficient energy for biological processes.
CO2 Regulation:
- Carbon Dioxide Production: The body produces carbon dioxide (CO2) as a byproduct of metabolism, which can combine with water to form carbonic acid (H2CO3) in the blood.
- Respiratory Rate Control: The respiratory system regulates blood CO2 levels by adjusting the rate and depth of breathing. Increased breathing expels more CO2, reducing acidity (raising pH), while decreased breathing retains CO2, increasing acidity (lowering pH).
pH Maintenance:
- Buffering System: The carbonic acid-bicarbonate buffering system helps maintain blood pH within a narrow range (7.35-7.45). Increased CO2 leads to higher H2CO3 and lower pH, while decreased CO2 raises pH.
- Response to Metabolic Changes: During metabolic acidosis (e.g., due to exercise or high protein intake), increased CO2 levels stimulate deeper and faster breathing to expel CO2 and restore pH balance.
- Compensation for Metabolic Disturbances: In cases of metabolic alkalosis (e.g., from vomiting), the respiratory system may slow down to retain CO2 and help lower pH back to normal.
Coordination with Kidneys:
- Integration with Renal Function: The respiratory and renal systems work together to maintain acid-base balance. While the respiratory system adjusts CO2 levels quickly, the kidneys manage bicarbonate and hydrogen ion levels over a longer period.
- Homeostatic Mechanism: This coordination ensures that both short-term and long-term adjustments are made to maintain stable pH levels in the body.
Thermoregulation Mechanism:
- Set Point Regulation: The hypothalamus acts as the body’s thermostat, maintaining a set point for normal body temperature (approximately 37°C or 98.6°F).
- Temperature Sensors: It receives input from thermoreceptors located in the skin and within the body (peripheral and central thermoreceptors), providing information about internal and external temperature changes.
Responses to Temperature Changes:
- Heat Loss Mechanisms: When body temperature rises above the set point, the hypothalamus activates mechanisms for heat loss, including:
- Vasodilation: Blood vessels in the skin dilate, increasing blood flow to the surface, allowing heat to dissipate.
- Sweating: Sweat glands are stimulated to produce sweat, which cools the body through evaporation.
- Heat Production Mechanisms: When body temperature drops below the set point, the hypothalamus triggers heat-producing mechanisms, such as:
- Vasoconstriction: Blood vessels constrict, reducing blood flow to the skin and minimizing heat loss.
- Shivering: Muscles contract involuntarily (shivering), generating heat through increased metabolic activity.
- Increased Metabolism: The hypothalamus may stimulate the release of hormones (e.g., thyroid hormones) that increase metabolic rate, producing more heat.
Integration with Other Systems:
- Hormonal Regulation: The hypothalamus interacts with the endocrine system to regulate body temperature through hormones that influence metabolism and heat production.
- Behavioral Responses: The hypothalamus also influences behavioral responses to temperature changes, such as seeking shade or wearing appropriate clothing to maintain thermal comfort.
- Homeostatic Balance: By coordinating these responses, the hypothalamus ensures that body temperature remains within the narrow range necessary for optimal physiological function.
Transportation of Nutrients:
- Absorption from the Digestive System: After digestion, nutrients (e.g., glucose, amino acids, fatty acids, vitamins, and minerals) are absorbed into the bloodstream from the intestines, primarily through capillaries in the intestinal villi.
- Distribution via Blood Vessels: The circulatory system, composed of arteries, veins, and capillaries, transports absorbed nutrients to tissues and organs throughout the body.
Key Functions:
- Delivery to Cells: Nutrient-rich blood from the digestive tract is transported to the liver via the hepatic portal vein for processing and then distributed to other cells for energy, growth, and repair.
- Homeostasis Maintenance: The circulatory system helps maintain nutrient balance by adjusting the flow of blood to various organs based on their metabolic needs, ensuring that tissues receive adequate nutrients.
- Hormonal Transport: Hormones released from endocrine glands are carried in the bloodstream to target tissues, regulating nutrient metabolism and utilization.
- Waste Removal: The circulatory system also facilitates the removal of metabolic waste products (e.g., carbon dioxide and urea), ensuring that nutrient transport is coupled with waste elimination.
- Temperature Regulation: By redistributing blood flow, the circulatory system also plays a role in regulating body temperature, impacting nutrient utilization and metabolic efficiency.
- Interaction with Other Systems: The circulatory system integrates with the respiratory system for gas exchange, ensuring that cells receive sufficient oxygen, which is essential for effective nutrient metabolism.
Reflex Arc Components:
- Receptor: A sensory receptor detects a stimulus (e.g., heat, pain) and generates an electrical signal (action potential).
- Sensory Neuron: The sensory neuron transmits the signal to the spinal cord or brain, providing information about the stimulus.
- Integration Center: In the spinal cord, interneurons process the incoming signal and coordinate an appropriate response, usually without involving the brain for speed.
- Motor Neuron: The motor neuron carries the signal from the spinal cord to the effector (e.g., muscle or gland) to execute the response.
- Effector: The effector carries out the response (e.g., muscle contraction or gland secretion), completing the reflex action.
Characteristics of Reflex Actions:
- Rapid Response: Reflex actions are typically quick (milliseconds) because they bypass higher brain functions, allowing for immediate responses to potentially harmful stimuli.
- Involuntary Nature: Reflexes occur automatically without conscious thought, making them crucial for survival and protection.
- Types of Reflexes: There are two main types of reflexes:
- Somatic Reflexes: Involve skeletal muscles (e.g., withdrawal reflex when touching something hot).
- Autonomic Reflexes: Involve smooth muscles or glands (e.g., heart rate regulation).
- Adaptability: Although reflexes are often fixed, they can be modified through experience and learning, a process known as conditioning.
Clinical Significance:
- Diagnostic Tool: Reflex responses are commonly tested in clinical settings (e.g., patellar reflex) to assess the integrity of the nervous system.
- Protection Mechanism: Reflex actions help protect the body from injury by providing quick responses to harmful stimuli, reducing potential damage.
Sliding Filament Theory:
- Actin and Myosin Interaction: Muscle contraction is primarily driven by the interaction between the thin filaments (actin) and thick filaments (myosin) within muscle fibers.
- Calcium Release: Upon stimulation by an action potential, calcium ions are released from the sarcoplasmic reticulum into the muscle fiber’s cytoplasm.
- Binding Sites Exposure: Calcium binds to troponin, causing a conformational change that moves tropomyosin away from actin's binding sites, allowing myosin heads to attach to actin.
- Cross-Bridge Formation: Myosin heads, which are in a "cocked" position due to ATP hydrolysis, bind to actin, forming cross-bridges.
- Power Stroke: Once bound, the myosin head pivots, pulling the actin filament toward the center of the sarcomere (the contractile unit of muscle), resulting in muscle shortening (contraction).
- Detachment and Resetting: ATP binds to the myosin head, causing it to detach from actin. The ATP is then hydrolyzed, "re-cocking" the myosin head for another cycle of contraction.
Regulation of Muscle Contraction:
- Neurotransmitter Release: The process begins with the release of acetylcholine at the neuromuscular junction, generating an action potential in the muscle fiber.
- Excitation-Contraction Coupling: The action potential travels along the sarcolemma and down T-tubules, triggering calcium release from the sarcoplasmic reticulum.
- Role of ATP: ATP is crucial for both the binding and detachment of myosin heads and for pumping calcium back into the sarcoplasmic reticulum after contraction, allowing muscles to relax.
Components of the Endocrine System:
- Endocrine Glands: The endocrine system comprises glands such as the pituitary, thyroid, adrenal, pancreas, and gonads that secrete hormones into the bloodstream.
- Hormonal Regulation: Hormones act as chemical messengers that regulate various physiological processes, maintaining internal balance despite external changes.
Homeostatic Functions:
- Metabolic Control: The endocrine system regulates metabolism through hormones like insulin, glucagon, thyroid hormones, and cortisol, ensuring that energy production and utilization are balanced.
- Water and Electrolyte Balance: Hormones such as ADH and aldosterone help maintain fluid balance and electrolyte levels, preventing dehydration and ensuring proper cellular function.
- Temperature Regulation: The thyroid gland secretes hormones that influence metabolic rate and heat production, playing a role in thermoregulation.
Response to Stress:
- Stress Hormones: In response to stress, the adrenal glands release hormones like adrenaline and cortisol, facilitating the “fight or flight” response and helping the body cope with challenges.
- Adaptation to Environmental Changes: The endocrine system allows for adaptation to changes in the environment (e.g., changes in temperature, diet) through hormonal adjustments.
Growth and Development:
- Regulatory Hormones: Hormones like growth hormone and sex hormones regulate growth and development, ensuring proper physical and sexual maturation throughout life stages.
- Reproductive Health: The endocrine system controls reproductive functions and processes, including the menstrual cycle, ovulation, and sperm production.
Integration with Other Systems:
- Collaboration with the Nervous System: The endocrine system works in concert with the nervous system to coordinate responses to stimuli, ensuring that the body reacts appropriately to internal and external changes.
- Feedback Mechanisms: Negative feedback loops are fundamental to maintaining homeostasis, where an increase or decrease in hormone levels triggers responses that restore balance.
Stages of the Cell Cycle:
- Interphase: The longest phase, where the cell prepares for division. It consists of:
- G1 phase (Gap 1): The cell grows, synthesizes proteins, and produces organelles.
- S phase (Synthesis): DNA is replicated, resulting in two copies of each chromosome (sister chromatids).
- G2 phase (Gap 2): The cell continues to grow and prepares for mitosis, checking for DNA errors and duplicating organelles.
- M phase (Mitosis): The phase where cell division occurs, consisting of several sub-stages:
- Prophase: Chromatin condenses into visible chromosomes, and the nuclear envelope begins to break down.
- Metaphase: Chromosomes align at the metaphase plate, and spindle fibers attach to centromeres.
- Anaphase: Sister chromatids are pulled apart toward opposite poles of the cell.
- Telophase: Chromatids reach the poles, the nuclear envelope reforms, and chromosomes begin to decondense.
- Cytokinesis: Often considered the final stage, cytokinesis divides the cytoplasm, resulting in two separate daughter cells.
Significance of the Cell Cycle:
- Growth and Development: The cell cycle is essential for organismal growth, tissue repair, and development by facilitating cell proliferation.
- Genetic Stability: Accurate DNA replication and distribution during the cell cycle ensure that daughter cells receive identical genetic information, maintaining genetic stability.
- Cellular Regulation: The cell cycle is tightly regulated by checkpoints (G1, G2, and M checkpoints) that monitor for errors or damage, preventing uncontrolled cell division and potential cancer development.
- Differentiation: Certain cells exit the cell cycle and enter a quiescent state (G0) for specialization, which is crucial for forming different tissues and organs.
- Adaptation to Environment: The cell cycle allows cells to adapt to their environment by responding to external signals (growth factors, nutrients) that influence division and differentiation.
- Research and Medicine: Understanding the cell cycle is vital in cancer research, as many therapies target specific stages to inhibit tumor growth and proliferation.
Genetic Information Storage:
- Blueprint of Life: DNA (deoxyribonucleic acid) carries the genetic instructions necessary for the development, functioning, growth, and reproduction of all living organisms.
- Nucleotide Structure: DNA is composed of nucleotides, each containing a phosphate group, a sugar (deoxyribose), and a nitrogenous base (adenine, thymine, cytosine, or guanine).
- Double Helix Structure: DNA exists as a double helix, with complementary base pairing (A with T, C with G) providing stability and enabling accurate replication.
Role in Replication:
- Semi-Conservative Replication: During cell division, DNA replicates in a semi-conservative manner, where each new DNA molecule consists of one original strand and one newly synthesized strand.
- Enzymatic Action: Enzymes (e.g., DNA polymerase) play crucial roles in unwinding the double helix and synthesizing new strands, ensuring the faithful transmission of genetic information to daughter cells.
Gene Expression and Traits:
- Coding for Proteins: Genes are segments of DNA that encode instructions for synthesizing proteins, which perform various functions in the body and determine traits (phenotypes).
- Regulation of Gene Expression: The expression of genes is tightly regulated, influenced by internal signals and environmental factors, ensuring that proteins are produced at the right time and in appropriate amounts.
Inheritance Patterns:
- Mendelian Inheritance: DNA is passed from parents to offspring, following patterns of inheritance (e.g., dominant and recessive traits) described by Gregor Mendel.
- Genetic Variation: Mutations, genetic recombination during meiosis, and independent assortment contribute to genetic diversity, which is essential for evolution and adaptation.
Biotechnological Applications:
- Genetic Engineering: Advances in DNA technology allow for genetic modification, cloning, and gene therapy, with applications in medicine, agriculture, and research.
- Forensic Science: DNA analysis is used in forensic science for identification and paternity testing, highlighting its significance in legal contexts.
Components of the Immune System:
- Innate Immunity: The first line of defense, including physical barriers (skin, mucous membranes) and immune cells (phagocytes, natural killer cells) that respond quickly to pathogens.
- Adaptive Immunity: A specific response involving lymphocytes (B cells and T cells) that provide targeted defense against particular pathogens, with memory cells facilitating long-term immunity.
Mechanisms of Defense:
- Phagocytosis: Immune cells (e.g., macrophages, neutrophils) engulf and digest pathogens, removing them from circulation.
- Antibody Production: B cells produce antibodies that bind to specific antigens on pathogens, neutralizing them or marking them for destruction.
- Cell-Mediated Immunity: T cells (e.g., cytotoxic T cells) directly kill infected or cancerous cells and help regulate the immune response by secreting cytokines.
- Inflammation: In response to infection or injury, inflammatory signals increase blood flow to the affected area, recruiting immune cells to fight pathogens and initiate healing.
Immunological Memory:
- Primary Response: Upon first exposure to a pathogen, the immune system mounts a primary response, resulting in the production of memory B and T cells.
- Secondary Response: Upon re-exposure, the immune system can respond more rapidly and effectively due to the presence of memory cells, providing long-lasting immunity.
Vaccination:
- Preventative Measure: Vaccines stimulate the immune system to recognize and combat specific pathogens without causing disease, enhancing immunity through the creation of memory cells.
- Herd Immunity: Widespread vaccination can lead to herd immunity, protecting those who cannot be vaccinated (e.g., immunocompromised individuals) by reducing the overall prevalence of disease.
Dysregulation of the Immune System:
- Autoimmunity: Sometimes, the immune system mistakenly attacks the body’s own cells, leading to autoimmune diseases (e.g., rheumatoid arthritis, lupus).
- Allergies: The immune system may overreact to harmless substances (allergens), resulting in allergic reactions that can vary in severity.
Hormonal Functions:
- Chemical Messengers: Hormones are signaling molecules secreted by endocrine glands into the bloodstream, regulating various physiological processes throughout the body.
- Target Specificity: Hormones act on specific target cells or organs that possess receptors for those hormones, leading to a cascade of physiological responses.
Regulation of Metabolism:
- Insulin and Glucagon: Insulin lowers blood glucose levels by facilitating cellular uptake, while glucagon raises blood glucose levels by promoting glycogenolysis and gluconeogenesis.
- Thyroid Hormones: Thyroid hormones (T3 and T4) regulate metabolism, influencing energy production and growth, and affecting nearly every tissue in the body.
Growth and Development:
- Growth Hormone: Secreted by the pituitary gland, growth hormone stimulates growth, cell reproduction, and regeneration in tissues, playing a crucial role in development during childhood and adolescence.
- Sex Hormones: Estrogen and testosterone are involved in sexual development and reproductive functions, influencing secondary sexual characteristics and regulating menstrual cycles.
Homeostasis Maintenance:
- Water Balance: Antidiuretic hormone (ADH) regulates water reabsorption in the kidneys, controlling blood volume and pressure.
- Calcium Homeostasis: Parathyroid hormone (PTH) and calcitonin work antagonistically to regulate calcium levels in the blood, essential for bone health and various cellular functions.
Stress Response:
- Adrenaline (Epinephrine): Released in response to stress, adrenaline prepares the body for “fight or flight” by increasing heart rate, dilating airways, and mobilizing energy stores.
- Cortisol: As a glucocorticoid hormone, cortisol regulates metabolism and the immune response during prolonged stress, helping the body cope with challenges.
Reproductive Functions:
- Regulation of Menstrual Cycle: Hormones like luteinizing hormone (LH) and follicle-stimulating hormone (FSH) control ovulation and menstrual cycles in females, while testosterone regulates spermatogenesis in males.
- Pregnancy Maintenance: Hormones such as progesterone and human chorionic gonadotropin (hCG) play essential roles in maintaining pregnancy and supporting fetal development.