Biology: Chapter 11 Part 2 Human Body Systems

11.8 The Respiratory System

  • The respiratory system facilitates gas exchange, bringing oxygen into the body and expelling carbon dioxide.
  • Breathing involves inhalation (drawing air in) and exhalation (expelling air out) from the lungs.
  • The extensive branching of airways in the lungs results in a large surface area for gas exchange.

11.8 Gas Exchange

  • Oxygen diffuses from the alveoli, which are tiny air sacs in the lungs, into blood capillaries to fuel body metabolism.
  • The circulatory system transports oxygen from the lungs to body cells.
  • Carbon dioxide, a metabolic waste product, diffuses from body cells into capillaries.
  • The circulatory system transports carbon dioxide from the body's cells to the lungs, where it is exhaled.
  • Alveoli: delicate, thin-walled elastic sacs at the end of bronchioles are where air meets the blood vessels.
  • Inhaled oxygen diffuses from the alveoli into the bloodstream.

11.8 Alveoli and Surface Area

  • Each lung contains approximately 300 million alveoli, resulting in a total surface area equivalent to the size of a tennis court.
  • The inner surface of alveoli is uneven, further increasing the surface area.
  • The trachea in the throat subdivides into bronchi, which further subdivide into bronchioles, each terminating in alveoli.

11.8 Breathing Mechanism

  • Breathing involves the use of the entire chest cavity.

  • Respiratory structures include:

    • Bones: ribs
    • Muscles:
      • Intercostal muscles (between ribs)
      • Diaphragm

  • Inhalation:

    • Chest muscles contract.
    • The chest cavity expands.
    • Air is drawn into the lungs.

  • Exhalation:

    • Chest muscles relax.
    • The chest cavity returns to its original size.
    • Air is forced out of the trachea.

Hiccups and Wind

  • Hiccups are involuntary contractions of the diaphragm, accompanied by the closing of part of the vocal cords, producing a sound.
  • Causes:
    • Irritation of the nerve connecting the brain to the diaphragm.
    • Eating too much or too quickly.
    • Nervousness or excitement.
    • Stress.
    • Consuming carbonated beverages or alcohol.
    • Sudden temperature changes.
    • Swallowing air.
  • Getting the "wind knocked out of you" occurs when an impact causes the diaphragm to spasm, preventing the lungs from filling with air.

11.8 Respiratory System Disorders

  • Emphysema: damage or inflammation of the alveoli, often caused by long-term exposure to tobacco smoke or air pollution.
  • Bronchitis: infection of the bronchioles, primarily caused by viruses.
  • Pneumonia: fluid accumulation in the alveoli, mainly caused by viruses.
  • Colds and flu: primarily affect the upper respiratory tract and are caused by viruses.
  • Asthma: a chronic inflammation of the airways with multiple causes, including genetics, allergies, and infections.

11.9 The Circulatory System

Overview

  • The circulatory system is the body's transport system.
  • The heart pumps blood through a series of blood vessels.
  • Blood carries nutrients and wastes.
  • The heart and blood vessels collectively form the cardiovascular system.

Blood Volume and Circulation

  • Total blood volume: approximately 5 liters (about 1.3 gallons).
  • The body can survive losing about 40% of blood volume.
  • A standard blood donation involves about 10% of total blood volume.
  • Closed Circulatory System:
    • Blood remains contained within vessels (tubes).
    • A muscular heart propels blood through vessels to tissues throughout the body.
    • Occurs in all vertebrates.
    • Note: Some invertebrates, such as insects, have blood contained in an open body cavity.

Blood Vessel Length

  • Total length of blood vessels: approximately 9,000-19,000 km (6,000-12,000 miles).

11.9 Function of the Circulatory System: Transport

  • Oxygen (carried by red blood cells)
  • Nutrients
  • Waste products
  • Immune system cells (white blood cells)
  • Hormones
  • Heat

11.9 Types of Blood Vessels

  • Arteries (and smaller arterioles): carry blood away from the heart (thick-walled, high pressure).
  • Veins (and smaller venules): carry blood to the heart (thin-walled, low pressure).
  • Capillaries: connect arterioles to venules
  • The protein transporting oxygen in the blood of octopuses and lobsters, hemocyanin, is blue leading to their blue blood.

Veins and Arteries

  • Strong contractions of the heart push blood into the arteries toward the body tissues.
  • Pressure decreases as it disperses through capillaries.
  • One-way valves in veins prevent blood from flowing backward.
  • If the valves don’t work properly, veins can enlarge (“varicose veins”), which can be painful.
  • Muscles around the veins contract and push the blood back toward the heart.

11.9 Cardiovascular Circuits

  • The pulmonary circuit: shuttles blood from the heart to the lungs.
  • The systemic circuit: shuttles blood from the heart to the rest of the body.

The Human Heart

The flow of blood: Body → Vena Cava → Right Atrium → Right Ventricle → Pulmonary artery → Lungs → Pulmonary vein → Left atrium → Left Ventricle → Aorta (artery).

Heart Rate

  • Release of Adrenaline (a hormone) causes premature beat and a faster heart rate.

11.9 Vascular System Disorders

  • Hypertension (high blood pressure): increases the risk of heart attack, heart disease, and stroke.
  • Anemia: occurs when the blood doesn’t carry enough oxygen.
  • Stroke: occurs when a clot or broken vessel prevents blood from getting to your brain.
  • Heart disease: results from fatty deposits blocking the arteries and is the most common cause of death in the USA
  • Buildup of fatty deposits, plaque, is usually the result of a gradual process called atherosclerosis.
  • Blockage causes a myocardial infarction, or heart attack.

11.9 Blood Composition

  • Plasma: about 55% of blood
    • Salty water (generally 90% of plasma)
    • Other molecules:
      • Metabolites
      • Wastes
      • Ions
      • Proteins
  • Cells: about 45% of blood
    • Red blood cells (generally more than 95% cells)
    • White blood cells
    • Platelets (cell fragments)

Red Blood Cells

  • RED BLOOD CELLS (ERYTHROCYTES)
  • Flexible disks containing no nucleus (in humans)
  • Transport Oxygen from the lungs to the rest of the body
  • Packed full of the protein hemoglobin (which binds to Oxygen)

Carbon Monoxide Poisoning

  • Carbon monoxide binds very strongly to the iron atoms in hemoglobin, the principal oxygen-carrying compound in blood.
  • The bond between CO and hemoglobin is 200 times stronger than the bond between hemoglobin and oxygen.
  • When CO binds to the hemoglobin it cannot be released nearly as readily as oxygen would be.
  • CO Statistics in the USA per year
    • Over 400 people die
    • Over 14,000 people are hospitalized

White Blood Cells

  • WHITE BLOOD CELLS (LEUKOCYTES)
  • Destroy pathogens and foreign organisms in the bloodstream and interstitial fluid
  • There are several types of white blood cells that differ in their methods of fighting disease and responding to foreign materials

11.11 Blood Clotting

  • Blood contains self-sealing substances that respond to injury: Clotting
  • Almost immediately after damage, platelets* form a sticky plug that can seal a minor break.
  • Molecules of fibrin cross-link to form a clot which, if on your skin, is called a scab.

*Platelets are fragments of cells with no organelles

  • Lack of platelets affects functioning clotting factors, cuts and scrapes can lead to uncontrolled bleeding.