Week 4

• What are the main components of blood?

  Blood is a combination of plasma, platelets, red blood cells, and white blood cells.
• What is the primary component of plasma?

  The majority of plasma is water, making up 92% of its composition.
• What is the function of platelets in blood?

  Platelets are cell fragments involved in clotting.
• What is the role of stem cells in the body?

  Stem cells have the unique ability to develop into various types of cells with specific functions.
• What is the function of erythrocytes (RBCs)?

  Erythrocytes transport O2 from the lungs to tissues and to a limited degree transport CO2 from tissues to lungs.
• What percentage of CO2 is carried by hemoglobin (Hb)?

  Hemoglobin carries 23% of CO2.
• What is the primary function of leukocytes (WBCs)?

  Leukocytes defend against microbial invasion and foreign bodies.
• What type of leukocyte is usually the first to arrive at the site of infection?

  Neutrophils are usually the first phagocytes to arrive to attack pathogens and foreign debris.
• What is atherosclerosis?

  Atherosclerosis is when plaque builds up inside the walls of arteries.
• What can atherosclerosis lead to?

  Atherosclerosis can lead to heart attacks, strokes, and peripheral artery disease.
• What is a heart attack?

  A heart attack is damage or death of cardiac muscle tissues resulting from blockage of a coronary artery.
• What is a stroke?


  A stroke is the death of nervous tissue in the brain due to lack of oxygen.
• What are LDL and HDL in relation to cardiovascular diseases?

  LDL delivers cholesterol to cells, while HDL scavenges excess cholesterol for return to the liver.
• How does hypertension affect cardiovascular health?

  Hypertension can damage the endothelium of arteries and promote plaque formation.
• What is gas exchange?


  Gas exchange is the uptake of molecular oxygen from the environment and discharge of carbon dioxide to the environment.
• What is a partial pressure gradient?

  A partial pressure gradient is the pressure exerted by a particular gas in a mixture of gases.
• Why is breathing in air easier than in water?

  Air is much less dense and less viscous than water, making it easier to move and force through small openings.
• What percentage of O2 do humans extract from the air they inhale?

  Humans only extract about 25% of O2 from the air they inhale.
• How have aquatic animals adapted for gas exchange?


  Aquatic animals have adapted to enable efficient gas exchange because it takes much energy to extract oxygen from water.
• What are the steps in the evolution of fish respiration?

  1. Earlier respiration mechanism: skin diffusion of oxygen.
  2. Rise of gills: primary respiratory organ in most fish species.
  3. Adaptations for specific environments: fish adapt respiration mechanisms.
  4. Continued evolution: fish evolve to changing environmental conditions.
• How does gas exchange occur in gills of aquatic animals?

  Oxygen dissolved in water diffuses into capillaries of gill filaments to oxygenate blood.
• What is the counter-current system in fish gills?

  The counter-current system allows maximum oxygen to be absorbed by blood from water by maintaining a concentration gradient throughout the gills.
• What is the function of the insect tracheal system?

  The insect tracheal system is a network of air tubes that branch throughout the body for gas exchange.
• What is the pathway of inhaled air in the mammalian respiratory system?

  Inhaled air passes from the nasal cavity to the pharynx, larynx, trachea, bronchi, and ends in microscopic alveoli.
• What is the role of surfactant in the lungs?

  Surfactant is a mixture of fat and proteins that coats alveoli and prevents them from sticking together when exhaling.
• What is tidal volume?

  Tidal volume is the volume of air inhaled and exhaled with each breath.
• What is vital capacity?

  Vital capacity is the tidal volume during maximum inhalation and exhalation.
• What is residual volume?

  Residual volume is the air that remains in the lungs after a forced exhalation.
• How is breathing controlled in humans?

  Breathing control in humans is mostly involuntary and regulated by neurons in the brain.
• What happens to blood pH during exercise?

  During exercise, increased CO2 dissolves in blood, forming carbonic acid which lowers blood pH.
• How do receptors in the brain respond to a drop in blood pH?

  Receptors in the brain sense the drop in pH and send nerve signals to increase breathing rate.
• What adaptations do animals have for gas exchange?

  Many animals have respiratory pigments that facilitate the exchange of O2 and CO2.
• What is apneustic breathing?

  Apneustic breathing is rapid breathing prior to a dive that allows lungs to remove 90% of O2 from air.
• What is myoglobin?

  Myoglobin is a protein that muscles contain to hold oxygen in tissues.
• What is a pathogen?

  A pathogen is a bacterium, fungus, virus, protozoan, or other disease-causing agent.
• What is innate immunity?

  Innate immunity is a rapid response that relies on a small set of receptor proteins to recognize molecules absent from animal bodies.
• What are the barrier defenses in innate immunity?


  Barrier defenses include intact skin and mucous membranes that prevent the entry of pathogens.
• What is phagocytosis?

  Phagocytosis is the process by which certain immune cells engulf and destroy pathogens.
• What are natural killer cells?

  Natural killer cells are a type of immune cell that provides innate defense against infected or tumor cells.
• What is the role of interferons in innate immunity?

  Interferons are proteins that provide innate defense by interfering with viral infections.