Week 12 : Cardiovascular System

RESPIRATORY SYSTEM

 Functions: (To provide a constant supply of oxygen to keep your body cells functioning / To remove carbon dioxide from the body cells. )

The Respiratory Tract:

  1. nostrils: opening to the nasal passages
  2. nasal passages: lined with a mucus membrane bearing cilia (warms, moistens, and filters incoming air)
  3. pharynx (throat)–cavity in back of mouth
  4. glottis: windpipe or trachea opening
  5. epiglottis–muscular flap covering the glottis–prevents food from entering the windpipe
  6. larynx (voice box) upper part of the windpipe containing sound producing vocal cords
  7. trachea: (windpipe)–about 4 inches long & 1 inch in diameter –supported by rings of cartilage –lined with a ciliated mucus membrane which filters incoming air
  8. bronchi: two main branches of trachea which enter lungs –lined with cartilage and ciliated
  9. bronchioles: smallest air tubes which end at the alveoli or air sacs –cartilage ring support “fades out” from this point on
  10. alveoli (air sacs): site of respiratory gas exchange by diffusion –resemble bunches of grapes –moist surface aids exchange–each alveolus is surrounded by capillaries & gas exchange occurs with them (oxygen in–carbon dioxide out)

 

  • Breathing – the mechanical part of respiration … involves both the diaphragm and rib cage muscles

 Some Respiratory System Malfunctions

  • pneumonia: alveoli fill with fluids and mucus resulting in coughing and breathing difficulties
  • asthma: allergic reaction in which bronchiole contractions create breathing difficulties
  • emphysema: air sacs lose their elasticity and breakdown resulting in a loss of respiratory surface in the lungs –shortness of breath is the chief symptom (smoking frequently leads to this disorder)

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CIRCULATORY SYSTEM

The main organ is the HEART.

Functions: (Generating blood pressure / Routing blood / Heart separates pulmonary and systemic circulations

  • Ensuring one-way blood flow
    • Heart valves ensure one-way flow
  • Regulating blood supply
    • Changes in contraction rate and force match blood delivery to changing metabolic needs

The heart functions as a double pump beating in unison.

  1. Deoxygenated blood–relatively low in oxygen
  2. Oxygenated blood–relatively high in oxygen

** Heartbeat is stimulated by an electrochemical impulse.

Pacemaker – in the right atrium – initiates the heartbeat

Pathway of a Red Blood Cell through the Heart

  1. Inferior & superior vena cava
  2. Right atrium
  3. Tricuspid Valve
  4. Right ventricle
  5. Pulmonary arteries

(BLOOD TO THE LUNGS – GAS EXCHANGE) …

  1. Pulmonary veins
  2. Left Atrium
  3. Mitral / Bicuspid Valve
  4. Left ventricle
  5. Aortic Valve
  6. Aorta

 

Blood 

  • In general, the blood is a fluid tissue helping to maintain homeostasis for all cells in the body.
  1. Transport of needed substances to body cells. (oxygen, amino acids, glucose, fatty acids, glycerol, salts, etc.)
  2. Transport of wastes from cells. (urea, water, carbon dioxide in the form of the bicarbonate ion)
  3. Helps to maintain a constant body temperature.
  4. Aids the body in fighting disease.

Blood Composition:

  • Plasma 55% (liquid part of the blood); Blood Cells 45%

 

Blood Cell Types:

  • Red Blood Cells:
    • most numerous
    • biconcave disc shaped
    • smaller than white blood cells, larger than platelets
    • no nucleus when mature
    • produced in the red marrow of long bones
    • destroyed in the liver and spleen
    • contain the iron protein compound HEMOGLOBIN whose chief function is to combine with oxygen and carry it to the cells
    • Carbon monoxide has 40X the affinity of oxygen for hemoglobin–breathing it may lead to death
  • White Blood cells

          –largest blood cells–several different types

–about 8,000 per drop of blood

–most are formed in the bone marrow or in the lymph tissue / most protect the body against

diseases by forming antibodies or engulfing bacteria

 

 Main White Blood Cell Types

  • Phagocytes— engulf bacteria and viruses by phagocytosis / able to leave the bloodstream and move between the cells of the body by squeezing through the capillary walls.
  • Lymphocytes–produce antibodies which clump bacterial poisons or bacteria (antigens) (antigens–foreign substances in the body)
  • Platelets – smallest blood cells (fragments) / 150,000 to 300,000 per drop of blood / needed for clotting

BLOOD VESSELS

  • Arteries — carry blood away from the heart / usually spurt blood when cut / all except the pulmonary artery carry oxygenated blood / thick walled and elastic / pulse: expansion and contraction of the artery walls in response to the heartbeat
  • Veins — carry blood toward the heart / contain valves / closer to the body surface than the arteries  / all except the pulmonary vein carry deoxygenated blood  / thinner, less muscular and elastic than arteries  / depend upon muscle and diaphragm movements for blood flow
  • Capillaries — most numerous vessels  / connect arteries to veins / microscopic, one cell thick walls  / site of much exchange between the blood and the intracellular fluid (lymph) by diffusion
  • Lymph vesselshave walls one cell thick / present around all body cells / Lymph composition is similar to that of blood except for the absence of RBC and some plasma proteins. / chief site of material exchange with the tissues

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CARDIOVASCULAR

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