Endocrine System Overview

Endocrine System

• Hormones are chemical messengers produced by glands in the endocrine system, regulating bodily functions and acting on target organs, tissues, or cells.
• Peptide hormones, composed of amino acids, are water-soluble and bind to cell surface receptors, triggering a signaling cascade.
• Steroid hormones, derived from cholesterol, are lipid-soluble, pass through cell membranes, and bind to intracellular receptors, regulating gene expression.

Hypothalamus

• The hypothalamus acts as both a neural and hormonal center, regulating the nervous and endocrine systems.
• Stimulatory hormones: TRH (Thyrotropin-releasing hormone), CRH (Corticotropin-releasing hormone)
• Inhibitory hormones: Somatostatin (inhibits growth hormone release), Dopamine (inhibits prolactin release)

cAMP

• cAMP (cyclic adenosine monophosphate) is a secondary messenger in cells.
• Formed from ATP by the enzyme adenylate cyclase, activated by a receptor on the cell surface.
• Activates protein kinase A (PKA), inducing or suppressing cellular responses.

Anterior and Posterior Pituitary

• Adenohypophysis (Anterior Pituitary): Hormones such as Growth hormone (GH), Thyroid-stimulating hormone (TSH), Adrenocorticotropic hormone (ACTH), Prolactin (PRL), Follicle-stimulating hormone (FSH), Luteinizing hormone (LH). Controlled by hypothalamic releasing/inhibiting hormones, acting on various target organs.
• Neurohypophysis (Posterior Pituitary): Hormones such as Oxytocin and Antidiuretic hormone (ADH). Released directly from the hypothalamus. ADH regulates urine production, while Oxytocin stimulates uterine contractions and milk release.

Hormonal Conditions

• Dwarfism: Growth hormone deficiency.
• Rickets: Vitamin D deficiency, leading to weakened bones.
• Gigantism: Excessive growth hormone during childhood.
• Acromegaly: Excessive growth hormone in adulthood, causing bone and tissue enlargement.
• Diabetes Insipidus: ADH deficiency, causing excessive urination and thirst.
• Diabetes Mellitus: Insulin deficiency or resistance, leading to high blood sugar.
• Hirsutism: Excessive hair growth, often due to high androgen levels.

Thyroid Gland

• Butterfly-shaped gland in the neck, regulating metabolism.
• Hormones: Thyroxine (T4), Triiodothyronine (T3), and Calcitonin, influencing metabolic rate and calcium levels.

Adrenal Glands

• Adrenal cortex produces hormones like cortisol (stress response), aldosterone (regulates sodium and potassium levels), and androgens.
• Adrenal medulla produces epinephrine (adrenaline) and norepinephrine (noradrenaline), involved in the "fight or flight" response.

Pancreas

• Endocrine cells in the pancreas include alpha cells, secreting glucagon, and beta cells, secreting insulin.
• Type 1 diabetes: Autoimmune destruction of beta cells, causing insulin deficiency.
• Type 2 diabetes: Insulin resistance, where cells don't respond to insulin properly.

Blood

• Blood functions in transporting oxygen and nutrients, regulating body temperature and pH, and providing protection.
• Hematocrit: Percentage of blood volume occupied by red blood cells (RBCs). Normal values vary based on gender.
• Blood plasma is composed primarily of water, proteins, electrolytes, nutrients, and hormones.
• Blood serum is blood plasma without fibrinogen, the blood-clotting protein.
• Blood contains formed elements: RBCs, WBCs, and platelets, each with specific roles and normal ranges.

Heart, Blood Vessels, and Circulation

• Heart function: Four-chambered pump driving blood through pulmonary and systemic circuits. Blood flows: Right atrium → Right ventricle → Pulmonary artery → Lungs → Pulmonary veins → Left atrium → Left ventricle → Aorta → Body
• Differences between foramen ovale and fossa ovalis: Foramen ovale is a fetal opening allowing blood to bypass the lungs. Fossa ovalis is the remnant of this opening in adults.
• Cardiac tissue: Striated, branched, and interconnected by intercalated discs, facilitating synchronized contractions
• Systemic and pulmonary circuits: Pulmonary circuit carries blood between heart and lungs; systemic circuit carries blood between heart and the rest of the body.

Lymphatic System

• Lymph: Clear fluid derived from interstitial fluid, containing waste products and immune cells (lymphocytes).
• Lymph flows through lymphatic capillaries, vessels, ducts, and trunks to the subclavian veins.
• Lymph nodes filter lymph, removing pathogens and debris.
• Lymphatic capillaries originate in tissues and are similar to veins with one-way valves to prevent backflow
• MALT (Mucosa-associated lymphoid tissue): Lymphoid tissue located in mucosal linings of gastrointestinal tract, genital tract, respiratory tract, and urinary tract.
• Immune response, filtering, and fluid balance regulation
• Components and location of lymph nodes

Immune System

• Half-life period: Time it takes for a substance's concentration to reduce by half in the body.
• Cytokines: Small proteins involved in cell signaling, like interferons that alert neighboring cells.
• Colony stimulating factors (CSFs): Proteins that stimulate the production of white blood cells (WBCs) and red blood cells (RBCs).
• Innate vs. Adaptive Immunity: Innate immunity is a rapid, non-specific defense, while adaptive immunity is slower and specific; both are vital for protection against various pathogens.
• Antibody types, and their role in immunity
• Immune response mechanisms including lymphocytes and cells, involved in recognizing and eliminating pathogens.

Respiratory System

• Pharynx: Connects the nasal and oral cavities to the larynx.
• Trachea: Connects pharynx to the lungs, with C-shaped cartilage providing support.
• Respiratory zones: Areas in the lungs where gas exchange occurs (alveoli and respiratory bronchioles).
• Cells in the alveoli (Type I and Type II) regulate gas exchange and surfactant production.
• Respiratory membrane: The thin layer separating air and blood, facilitating gas exchange.

Digestive System

• Monomers and polymers: Monomers are the smallest units of a molecule; polymers are large molecules formed from repeated monomer units. Digestion breaks down food polymers into absorbable monomers.
• Specific enzymes and their roles/locations in digestion: salivary amylase, pepsin, trypsin, chymotrypsin, pancreatic amylase, disaccharidases, and lipase for digesting carbohydrates, proteins, and lipids, respectively.
• Mucus secretion in the stomach (mucuous cells) and hydrochloric acid (parietal cells) from the stomach lining and their importance
• Nutrients needing and not requiring digestion.

Urinary System

• Parts of the kidney (cortex, medulla, and nephron), with cortical and juxtamedullary nephrons having different positions.
• Functions of the urinary system: removal of wastes, regulating blood volume and pressure, pH regulation and nutrient reabsorption.
• Blood vessel pathways related to the nephron
• Processes like glomerular filtration rate, filtrate production, and reabsorption

Fluid and Electrolyte Balance

• Fluids in the body include intracellular (inside cells) fluid, extracellular fluid (outside cells, including interstitial and plasma fluids).
• Electrolytes are charged particles crucial for physiological functions, and are key components in fluid balance.
• Osmoregulation: Maintenance of water and electrolyte balances in the body, typically by the kidneys and hormones.

Reproductive System

• Male: Sperm production, maturation, and transport from testes to external environment
• Female: Ovarian hormone production, ovulation, and fertilization, supporting and preparing the uterus, etc.
• Various hormones involved in reproduction for both sexes, including testosterone, estrogen, and progesterone
• Spermatogenesis, spermatiogenesis, fertilization, and development stages

Development and Inheritance

• Sperm penetration, first division after fertilization, and polyspermy prevention are key events in the early stages of development
• Events occurring throughout each trimester for pregnancy, including organogenesis, growth, and maturation
• Definitions of terms, such as Capacitation, Activation, Differentiation, Induction, and Predilection. Important in the early developmental processes of a fetus.

Explore the functions of hormones in the endocrine system and the role of the hypothalamus as a regulatory center. This quiz covers peptide and steroid hormones, their mechanisms, and the importance of cAMP in cellular signaling. Test your understanding of key concepts and hormones involved in these processes.