Immune System Quiz

Human Physiology Study Notes

• Human Physiology is the science that describes how organisms function and survive in continually changing environments.
• Balance is the key to life.

Body Fluids

• Fluid Intake:
  • Ingested water: 1200-1500 mL
  • Ingested food: 800-1100 mL
  • Metabolic oxidation: 300 mL
  • Total: 2600-3000 mL
• Fluid Output:
  • Kidneys: 1500 mL
  • Insensible loss through skin: 600-800 mL
  • Insensible loss through lungs: 400-600 mL
  • Gastrointestinal tract: 100 mL
  • Total: 2600-3000 mL

Extracellular Fluid (ECF)

• Cells exist in an extra-cellular fluid (sometimes called "Internal Environment") from which they take up oxygen and nutrients and discharge metabolic waste products.
• Solutions (mixtures) in physiology include a solvent (usually water) and solutes (ions, proteins, glucose, nutrients, oxygen, CO2).

Fluid Compartments

• 60% of body weight accounts for ~42 liters.
• Intracellular fluid: ~28 liters (≈ 67% TBW - 40% of body wt)
• Extracellular fluid: ~14 liters (≈ 33% TBW - 20% of body wt)
  • Plasma: ~3 liters
  • Interstitial fluid: ~11 liters
  • Transcellular fluid: ~1-2 liters (≈ 5% of body wt or 15% of ECF)

Factors Affecting Body Fluids

• Age (elderly < young)
• Gender
• Degree of Obesity
• Water intake and output
• Climate
• Physical activity levels
• Habits

Body Fluids Composition

• Capillary walls are permeable to electrolytes but not protein.
• Cell membranes are permeable to water but not electrolytes.

Regulating Electrolytes

• Sodium
• Potassium
• Calcium
• Magnesium
• Chloride
• Phosphate
• Bicarbonate

Electrolytes (Dissolved Ions)

• Major Positive Ions (Cations):
  • Sodium (Na+)
  • Potassium (K+)
  • Calcium (Ca2+)
  • Magnesium (Mg2+)
• Major Negative Ions (Anions):
  • Chloride (Cl-)
  • Bicarbonate (HCO3-)
  • Phosphate (HPO42-, H2PO₄⁻, HPO₂⁻)
  • Sulfate (SO₄²⁻)
  • Organic acids
  • Proteins

Actions of key electrolytes

• Na+: involved in generating action membrane potential of muscle and nerve cells.
• K+: maintains the resting membrane potentials of excitable cells (muscle and nerve cells) and is a major contributor to intracellular osmolarity and cell volume.
• Ca2+: involved in muscle contraction, control of hormones and neurotransmitters, blood clotting, cellular enzyme activation, and skeletal strengthening.
• Cl-: together with Na+, the main anion of plasma and interstitial fluid
• HCO3⁻ and HPO₄²⁻: stabilize pH in body fluids
• H+ and OH⁻: determine the degree of acidity in body fluids

Abnormalities of Salts and Water

• Hyperkalemia: Increased serum K+ levels (>5.5 mEq/L)
• Hypokalemia: Decreased serum K+ levels (<3.5 mEq/L)
• Hypernatremia: Increased serum Na+ levels (>145 mEq/L)
• Hyponatremia: Decreased serum Na+ levels (<130 mEq/L)
• Hypercalcemia: Increased serum Ca2+ levels (> 11.0 ml/dL))
• Hypocalcemia: Decreased serum Ca2+ levels (<9.0 mg/dL)

Water Intake and loss

• Water gained from ingestion of food , drinking water, and synthesis of water during oxidation of carbohydrates
• Water lost via respiration, skin, sweating, feces and urine

Levels of Organization

• Atoms: made up of subatomic particles
• Molecules: 2 or more atoms
• Macromolecules: small molecules joined together (e.g., carbohydrates, lipids, proteins, nucleic acids)
• Organelles: part of cells
• Cells: basic structural & functional unit of the body
• Tissues: Group of Similar cells
• Organs: 2 or more tissues working together
• Systems: Several organs working together
• Organisms: complete living things.

Cell Parts and Functions

• Nucleus: Contains DNA, site of ribosome production, stores information for protein synthesis
• Cytoplasm: Includes cytosol, cytoskeleton, organelles, and inclusions.
• Cell Membrane: selective barrier, permeable to lipid-soluble, non-polar substances and some small polar substances.
• Organelles: Endoplasmic reticulum (ER) - transport system, Ribosomes (protein synthesis), Golgi apparatus (modifies and packages proteins), Mitochondria (ATP production), Lysosomes (digestion), Peroxisomes (detoxification), Centrosome (cell division), Cilia (movement), Flagellum (movement), Microvilli (increase surface area).
• Vesicles: Store substances

Protein Synthesis from DNA

• First DNA is transcribed to mRNA
• Then mRNA moves to cytoplasm
• mRNA, tRNA, amino acids and ribosomes form a protein.

Movements into and out of the cell

• Passive Processes (Physical): Simple and facilitated diffusion; osmosis.
• Active Processes (Physiological): Active transport; endocytosis, and exocytosis.

Simple Diffusion

• Movement of substances from higher concentrations to lower concentrations.

Facilitated Diffusion

• Diffusion across a membrane with the help of a channel or carrier molecule.

Osmosis

• Movement of water through a selectively permeable membrane from regions of higher water concentration to lower water concentration.

Osmotic Pressure

• Ability of osmosis to generate enough pressure to move a volume of water.

Effects of Different Solutions on Red Blood Cells

• Isotonic: Solute and water concentration are the same inside and outside of the cell.
• Hypertonic: Solute concentration is higher outside the cell than inside the cell.
• Hypotonic: Solute concentration is lower outside the cell than inside the cell.

Active Transport

• Carrier molecules transport substances across a membrane from regions of lower concentration to regions of higher concentration and requires energy.

Sodium - Potassium Pump

• Active transport mechanism.
• Creates balance by pumping 3 Na+ out of the cell and 2 K+ into the cell. (3:2 ratio)

Endocytosis

• Cell engulfs a substance by forming a vesicle around the substance, including pinocytosis, phagocytosis, and receptor-mediated endocytosis.

Exocytosis

• Contents of the vesicle are released outside of the cell, such as neurotransmitters.

Saturation

• Both facilitated diffusion & active transport require the use of carriers specific to particular substances; therefore both can exhibit saturation.

Homeostasis

• Maintaining a relatively constant internal environment in an organism. Receptors provide data about changes in the internal environment to Effectors(organ systems), which response.

Negative Feedback Mechanism

• Receptors sense and deviation from normal range. The effectors work to return it to normal again. (e.g.; body sweat to lower body temp if hot).

Positive Feedback Mechanism

• Receptors sense that the body needs more power and the effectors respond by increasing or strengthening what is happening. (e.g. child birth).

Blood (RBCs) Morphology & Characteristics

• Biconcave discs, able to change its shape, and allowing it to form rouleaux inside narrow blood vessels.
• Lack of nucleus (so called corpuscles rather than cells) and many organelles.
• Average lifespan ~ 120 days, destroyed by hemolysis in the spleen, obtain energy via anaerobic glycolysis.
• Transport hemoglobin molecules for oxygen transport.
• Contain carbonic anhydrase enzyme (for carbon dioxide transport)
• Can be counted by counting chambers in the blood. (5.2 X 10⁶/mm³ for male; 4.7 X 10⁶/mm³ for female)
• PCV or haematocrit value is the % of RBC in 100 cc of blood

RBC Production Sites

• In the first trimester of pregnancy (first 3 months): Yolk sac
• In the second trimester of pregnancy (second 3 months): Liver, spleen, & lymph nodes
• In the third trimester of pregnancy -5 Years of age: Bone marrow of all bone
• In 5 -20 years of age: Bone marrow of membranous bones and proximal part of long bones
• In 20 years and after: Bone marrow only of membranous bones

RBC Genesis (Erythropoiesis)

• The body must produce about 2.5 million new RBCs every second
• The rate is regulated by tissue oxygen levels.
• Hypoxia stimulates release of erythropoietin, which stimulates erythropoiesis in the bone marrow.

Hemoglobin (Hb) Molecule

• Globin: 4 polypeptide chains (2 alpha & 2 beta) chains
• Heme group (porphyrin ring with an iron in the center): 4 heme groups with 4 iron (Fe²⁺) that can bind to 4 O₂ molecules, forming oxyhemoglobin

RBC Death

• As RBCs get older, their membrane becomes less flexible and fragile.
• They are hemolyzed (destroyed) when they pass through capillaries of the spleen by macrophages.

Vitamin B12 & Folic Acid

• Needed for DNA synthesis. Deficiency decreases RBC production, causing enlarged RBCs (macrocytes) in megaloblastic anemia.
• Daily requirement of Vit. B12 ~ 5 µg.

Iron

• The total body iron is ~4 grams, mostly in hemoglobin.
• Daily requirement of iron for men ~ 1 mg and women ~ 2 mg.
• Deficiency can cause iron deficiency anemia.

Iron-Deficiency Anemia

• Decreased RBC count can lead to tissue hypoxa.
• Basic mechanism for RBC regulation is tissue oxygenation.
• Increased tissue oxygen demand stimulates erythropoietin release.

Anemia

• Deficiency of RBCs or hemoglobin.
• Can be due to slowed production (aplastic anemia), or rapid loss/destruction (blood loss anemia, hemolytic anemia).

Slow RBC Production Anemia

• Aplastic anemia: Bone marrow damage (e.g., X-ray radiation, drugs, infiltration). Characterized by pancytopenia (decrease in all blood cell types).
• Megaloblastic anemia: Decreased Vitamin B12, folate or intrinsic factor.

RBC Loss/Destruction Anemia

• Blood loss anemia: Result of bleeding (e.g., trauma, ulcers)
• Hemolytic Anemia: Abnormality in RBC (e.g., hereditary spherocytosis) or Hb (e.g., sickle cell anemia).
• Abnormality in membrane (e.g., G6PD deficiency).
• Antibody-antigen reaction on RBC membrane.

Polycythemia

• Abnormal increase in RBC count.
• Can be primary (due to stem cell tumor) or secondary (due to tissue hypoxia).

White Blood Cells (Leukocytes)

• Granulocytes: Neutrophils (inflammation and bacterial infections), Eosinophils (allergies and parasitic infections), Basophils (allergies and releases histamine/heparin).
• Agranulocytes: Lymphocytes (specific immune response), Monocytes (phagocytosis).

WBC Abnormalities

• Agranulocytosis: Bone marrow stops producing WBCs, leading to leukopenia (especially neutropenia). Multiple infections can occur, potentially lethal.
• Neutrophilia: Increased neutrophils, due to inflammation or bacterial infections.
• Eosinophilia: Increased eosinophils, occurs in allergic reactions and parasitic infections.
• Leukemia: Uncontrolled production of abnormal WBCs, due to carcinogenic mutations in myelogenous or lymphogenous cells. Classified as either acute or chronic.

Platelets

• Small disc-shaped cell fragments (cytoplasm of megakaryocytes) that circulate in the blood, are essential for hemostasis.
• About 150,000-400,000/mm3 in normal concentration.
• Platelets have no nuclei and cannot reproduce.
• Thrombopoietin is the regulator of platelet production.
• Lifecycle ~ 8-10 days.

Platelets Functions

• Essential for hemostasis (preventing blood loss)
  • Maintaining vascular integrity by sealing minor endothelial defects
  • Preventing bleeding by formation of platelet plugs
  • Contributing to the membrane (lipid procoagulant) activity to assess secondary hemostasis
  • Promotes vascular healing
  • Active in protein, carbohydrate, and lipid synthesis
  • Generate metabolic activities
  • Play role in factor VIII synthesis (fibrin stabilizing factor)

Hemostasis

• Prevention of blood loss. Steps:
  • Vascular spasm: Vessel contraction to reduce blood loss
  • Platelet plug formation: Platelets stick to collagen fibers, and become active to form a temporary plug.
  • Blood clot formation: Coagulation cascade forms a fibrin mesh, entrapping red blood cells and platelets

Anticoagulant Factors

• Heparin: inhibits blood coagulation in both vivo and vitro
• EDTA: chelating agent to remove Ca²⁺
• Oxalate Salts: precipitate Ca²⁺ ions, used when blood is to be examined outside the body (in vitro).
• Citrate salts : (an anticoagulant) is used to form insoluble Ca-citrate that prevents clotting.

Blood Groups

• ABO System: Has 4 blood groups (A, B, AB and O).
• Rh System: Inherited independently from the ABO system.
• Transfusion Reaction Due to Mismatched Blood Groups: Agglutination; hemolysis (RBCs rupture); Acute renal failure.

Erythroblastosis Fetalis (Rh Disease)

• Occurs when a Rh-ve mother carries a Rh+ve fetus.
• The mother's immune system attacks the fetus's RBCs leading to anemia and possibly death of the fetus. Proper injection of antibodies (Anti-D) to the Rh-ve mother within 72 hrs of childbirth may prevent the condition.

Heart Physiology

• Heart Structure: 4 chambers (2 atria, 2 ventricles)

• Heart Layers: Endocardium (inner lining), Myocardium (muscular layer), Pericardium (outer layer).

• Cardiac Muscle Cells: Contractile cells, Autorhythmic cells.

• Conductive System of the heart: Sinoatrial node (SA), Atrioventricular node (AV) , atrioventricular bundle (His bundle), right & left bundle branches, Purkinje fibers

• Heart Sounds: 1st sound – closing of the atrioventricular valves; 2nd sound – closing of the semilunar valves.

• Coronary Circulation: Blood circulating supply of the heart by vessels (coronary arteries and veins.)

  • Ischemic Heart Disease (IHD): Reduced oxygen supply to the heart.

• Myocardial Infarction (MI): Irreversible damage to myocardial tissue due to complete coronary artery occlusion.

• Heart Failure (HF): Inability of the heart to eject or fill with sufficient blood to meet the body's metabolic demands.

Test your knowledge about white blood cells and red blood cells in the immune system. This quiz covers their lifespan, function, and structural characteristics. Perfect for biology students wanting to deepen their understanding of human physiology.