Lecture Notes on Human Physiology

Respiratory and Digestive System Questions

1. Dalton’s Law of Partial Pressures and Henry’s Law

  • Dalton's Law of Partial Pressures:

    • States that the total pressure exerted by a mixture of gases is the sum of the pressures exerted by each individual gas in that mixture.

    • Mathematically expressed as:
      P{total} = P1 + P2 + P3 + … + Pn where Pi represents the partial pressures of each gas in the total mixture.

  • Henry’s Law:

    • States that when a mixture of gases is in contact with a liquid, each gas will dissolve in that liquid in proportion to its partial pressure.

    • This describes the relationship between the solubility of gases in liquids and their partial pressures, and is crucial for understanding gas exchange in biological systems.

2. Age-Related Changes in Respiratory Function

  • Structural and Functional Decline:

    • Gradual deterioration of lung structure and function occurs with aging.

  • Decreased Muscle and Cartilage Integrity:

    • Weaker airway muscles and cartilage can become prone to collapse or obstruction, limiting airflow.

  • Alveoli Changes:

    • Loss of shape and elasticity in alveoli reduces surface area necessary for effective gas exchange.

  • Diaphragm Weakness:

    • Weakened diaphragm diminishes the air capacity taken per breath.

  • Immune Function Impairment:

    • Reduced effectiveness of the immune system against lung infections due to aging.

  • Neurological Changes:

    • Decreased sensitivity of the nervous system to changes in oxygen and carbon dioxide levels may lead to abnormal breathing patterns.

3. Phases of Swallowing

  • Buccal Phase (Voluntary):

    • Food that has been chewed is pushed to the back of the mouth by the tongue, leading to the pharynx.

  • Pharyngeal-Esophageal Phase (Involuntary):

    • The autonomic nervous system takes over, transporting food through the pharynx, into the esophagus, and down into the stomach.

4. Definitions and Explanations

  • Defecation Reflex:

    • A physiological response to rectal distension due to fecal matter. It prepares the body for the elimination of stool through the anus.

  • Constipation:

    • An abnormal condition characterized by prolonged intervals between defecation greater than what is normal for an individual. It often involves hard stools.

  • Diarrhea:

    • An abnormal condition marked by increased frequency of defecation, typically associated with the excretion of watery stools.

5. Effects of Aging on Digestive System Activity

  • Slowed Digestive Processes:

    • Aging results in slower digestive system functions.

  • Reduced Saliva Production:

    • Less saliva can hinder food breakdown and swallowing.

  • Weakened Esophageal Muscles:

    • Causes difficulty in moving food along the esophagus.

  • Decreased Stomach Elasticity:

    • Contributes to a less effective stomach for food processing.

  • Slowed Colon Movement:

    • Results in issues like constipation and acid reflux.

  • Enzyme and Acid Production:

    • Decreased production can affect nutrient absorption negatively.

  • Susceptibility to Gastrointestinal Problems:

    • Aging increases risks for bacterial overgrowth and conditions like GERD and can worsen by medications.

Male/Female Reproductive Terms

  • Ampulla:

    • A localized dilation of a canal or duct; critical in reproductive anatomy.

  • Spermatogenesis:

    • The biological process of sperm formation (male gamete).

  • Placenta:

    • A temporary organ formed from fetal and maternal tissues; provides oxygen and nutrients to the developing fetus, transports metabolic waste away, and produces hormones vital for pregnancy.

  • Prepuce (Foreskin):

    • The loose skin covering the glans penis, forming a cuff around it.

  • Estrogen:

    • A hormone that stimulates the development of female secondary sex characteristics; key female sex hormone.

  • Scrotum:

    • The external sac that houses the testes, important for temperature regulation of sperm production.

  • Ovaries:

    • The female gonads responsible for egg production and hormone secretion.

  • Vasectomy:

    • A surgical birth control procedure involving the cutting and tying off (ligation) of the ductus deferens to prevent sperm from exiting the body.

  • Erection:

    • The physiological process of the penis enlarging and stiffening due to increased blood engorgement.

  • Menopause:

    • The phase in a woman's life where ovulation and menstruation cease due to hormonal changes.

  • Progesterone:

    • Hormone that plays a significant role in preparing the uterus for a fertilized ovum.

  • Sperm:

    • The male gamete involved in reproduction.

  • Prostate:

    • An accessory reproductive gland that contributes to semen volume and contains fluids necessary for sperm activation.

  • Puberty:

    • The developmental stage where individuals achieve reproductive maturity.

  • Climax:

    • The peak of sexual activity characterized by intense pleasure, rapid heartbeat, changes in respiration, elevated blood pressure, and rhythmic muscle contractions, leading to ejaculation in males.

  • Gonads:

    • Primary reproductive organs—testes in males and ovaries in females.

  • Endoderm:

    • The innermost cell layer in a developing embryo forming the epithelial lining of digestive and respiratory systems, together with associated glands.

  • Penis:

    • The male organ of copulation and urination.

  • Vagina:

    • A thin-walled tube connecting the cervix to the exterior; often referred to as the birth canal.

  • Spermatogonia:

    • Stem cells in the testes that develop into sperm; they divide by mitosis post-puberty to generate type A and type B daughter cells.

  • Seminal Plasmin:

    • A complex fluid containing proteins, sugars, and nucleic acids that nourish and enhance the motility of sperm, facilitate sperm-egg fusion, and modulate immunity and uterine receptivity to promote successful implantation.

Urinary System

  • Renal Cortex:

    • The light-colored outer region of the kidney characterized by a granular appearance.

  • Renal Pyramids:

    • Cone-shaped masses found in the kidney's medulla, formed of parallel bundles of collecting tubules and capillaries, giving them a striped appearance.

  • Nephron:

    • The structural and functional unit of the kidney, comprising the renal corpuscle and renal tubule.

  • Bowman's Capsule:

    • A part of the nephron that encases the glomerulus.

  • Water:

    • A universal solvent composed of two hydrogen atoms bonded to one oxygen atom; exists in all three states (liquid, gas, solid).

  • Solutes:

    • Substances dissolved in a solution, such as salts in water.

  • Collecting Ducts:

    • Structures that transport urine from nephrons to the renal pelvis.

  • Aldosterone:

    • A hormone synthesized by the adrenal cortex that regulates sodium reabsorption and potassium secretion in kidneys.

  • Kidney Filter Rate/Day:

    • Measurement of the volume of blood filtered by the kidneys, pivotal for understanding kidney function.

  • Antidiuretic Hormone (ADH):

    • A hormone produced by the hypothalamus and released by the posterior pituitary, which promotes water reabsorption in kidneys and decreases urine output.

  • Tubular Secretion:

    • The transport process where substances (like drugs and ions) move from the bloodstream into the renal filtrate.

  • Tubular Excretion:

    • The critical renal process where kidney tubules actively transport waste, toxins, and drugs from blood into the renal tubule, contributing to urine formation.

  • Renal Medulla:

    • The darker inner region of the kidney located beneath the renal cortex comprising cone-shaped masses called renal pyramids.

  • Renal Columns:

    • Extensions of renal cortex that separate the renal pyramids from one another.

  • Minor Calyx:

    • Cup-like structures that encase the papillae of renal pyramids and facilitate the drainage of urine into major calyces.

  • Major Calyx:

    • Extensions from the renal pelvis that collects urine from minor calyces and drains it into the renal pelvis.

Nutrients

  • Basal Metabolic Rate (BMR):

    • The rate of energy expenditure per unit time by endothermic animals at rest. Essential for maintaining life.

  • Thyroxine:

    • A primary hormone regulating BMR, crucial for determining metabolic rate.

  • Macronutrient:

    • Nutritional substances required in large amounts for health maintenance, including carbohydrates, lipids, and proteins.

  • Water:

    • Essential for almost all body functions; acts as a solvent, carrier, and temperature regulator.

  • Micronutrient:

    • Substances required in minute amounts, essential for numerous biochemical functions; includes vitamins and minerals.

  • Minerals:

    • Inorganic compounds occurring naturally; essential for many bodily processes, often working synergistically with enzymes.

  • Vitamins:

    • Organic molecules required in small amounts, often acting as coenzymes in various biochemical reactions.

  • Proteins:

    • Made of chains of amino acids serving as structural materials and enzymes in biological systems.

  • Lipids:

    • Biomolecules that serve as energy storage, structural components of cell membranes, and insulation.

  • Carbohydrates:

    • Provide the primary source of fuel for cellular energy and ATP production.

  • Triglycerides:

    • A type of lipid comprised of three fatty acid molecules; principal form of stored energy.

  • Alcohol:

    • Classified as providing "empty calories" devoid of essential nutrients, negatively affecting nutrient absorption and utilization, and may impair gut health leading to vitamin and mineral deficits.