Cystic Fibrosis
→ Thick mucus coagulates in ducts, produces obstruction, Too thick for cilia to move
 
→ Major Systems Affected: Respiratory System, G. I. Tract,Reproductive Tract

→ Inherited, autosomal recessive gene, most common fatal genetic disorder

→    Major characteristic, Altered electrolyte composition (Saliva & sweat Na+, K+, Cl-)

→    Family history of Cystic Fibrosis
→    Respiratory Infections & G.I.Tract malabsorption
→    Predisposes lung to Secondary infection (Staphylococcus, Pseudomonas)
→    Damages Respiratory Bronchioles and Alveolar ducts, Produces Fibrosis of Lungs, Large cystic dilations)

1. PATHOPHYSIOLOGY OF THE CONDUCTION SYSTEM


2. Cardiac arrhythmias = deviation from normal rate, rhythm

    

   1. Heart block (types) = conduction system damage
      1. Complete Heart Block = 3rd degree block
         1. idioventricular beat (35-45/min)
         2. Atria at normal sinus rhythm
         3. Periods of asystole (dizziness, fainting)
         4. Causes = myocardial infarction of ventricular septum, surgical correction of interseptal defects, drugs
      2. Incomplete Heart Block = 2nd degree block
         1. Not all atrial beats reach ventricle
         2. Ventricular beat every 2nd, 3rd, etc. atrial beat, (2:1 block, 3:1 block)
      3. Incomplete Heart Block = 1st degree block
         1. All atrial beats reach ventricle
         2. PR interval abnormally long = slower conduction
      4. Bundle branch blocks (right or left)
         1. Impulses travel down one side and cross over
         2. Ventricular rate normal, QRS prolonged or abnormal
   2. Fibrillation
      1. Asynchronous contractions = twitching movements
      2. Loss of synchrony = little to No output
      3. Atrial Fibrillation
         1. Irregular ventricular beat & depressed pumping efficiency
         2. Atrial beat = 125 - 150/min, pulse feeble = 60 - 70/min
         3. Treatment = Digitalis - reduces rate of ventricular contraction, reduces pulse deficit
      4. Ventricular Fibrillation
         1. Almost no blood pumped to systemic system
         2. ECG = extremely bizarre
         3. Several minutes = fatal
         4. Treatment = defibrillation, cardiac massage can maintain some cardiac output

Plasma:  is the straw-colored liquid in which the blood cells are suspended.

Plasma transports materials needed by cells and materials that must be removed from cells:

• various ions (Na⁺, Ca²⁺, HCO₃⁻, etc.
• glucose and traces of other sugars
• amino acids
• other organic acids
• cholesterol and other lipids
• hormones
• urea and other wastes

Most of these materials are in transit from a place where they are added to the blood

• exchange organs like the intestine
• depots of materials like the liver

to places where they will be removed from the blood.

• every cell
• exchange organs like the kidney, and skin.

DNA (Deoxyribonucleic acid) - controls cell function via transcription and translation (in other words, by controlling protein synthesis in a cell)

Transcription - DNA is used to produce mRNA

Translation - mRNA then moves from the nucleus into the cytoplasm & is used to produce a protein . requires mRNA, tRNA (transfer RNA), amino acids, & a ribosome

tRNA molecule

• sequence of amino acids in a protein is determined by sequence of codons (mRNA). Codons are 'read' by anticodons of tRNAs & tRNAs then 'deliver' their amino acid.
• Amino acids are linked together by peptide bonds (see diagram to the right)
• As mRNA slides through ribosome, codons are exposed in sequence & appropriate amino acids are delivered by tRNAs. The protein (or polypeptide) thus grows in length as more amino acids are delivered.
• The polypeptide chain then 'folds' in various ways to form a complex three-dimensional protein molecule that will serve either as a structural protein or an enzyme.

4.    Emphysema
1. Permanent enlargement of airways with distension of alveolar walls
 
    Thickened Bronchial Submucosa, Edema & Cellular Infiltration (loss of elasticity), Dilation of Air spaces, due to destruction of alveolar walls (Air trapped by obstruction)

2.    Lower Respiratory tree destruction

    Respiratory Bronchioles, Alveolar ducts, & Alveolar sacs

Types of Emphysema:
    
    1.    Centrilobular (Centriacinar) = Respiratory Bronchioles
    Rarely seen in non Smokers, More in Men than Women, Found in Smokers with Bronchitis

    2.    Panlobular (Panacinar) 

    Hereditary, Single autosomal recessive gene. Deficient in 1-globulin (1-antitrypsin), Protects respiratory tract from neutrophil elastase (Enzyme that distroys lung connective tissue) , Aged persons, Results from Bronchi or Bronchiolar constriction

    NOTE: Smoking = Leading cause of Bronchitis, Emphysema
 

Surface Tension

1.    Maintains stability of alveolus, preventing collapse

2.    Surfactant (Type II pneumocytes) = dipalmityl lecithin

3.    Type II pneumocyte appears at 24 weeks of gestation;
    1.    Surfactant production, 28-32 weeks;
    2.    Surfactant in amniotic fluid, 35 weeks.
    3.    Laplace equation for thin walled spheres P = 2T
        a.    P = alveolar internal pressure r
        b.    T = tension in the walls r = radius of alveolus
        
4.    During normal tidal respiration

    1.    Some alveoli do collapse (Tidal pressure can't open)
    2.    Higher than normal pressure needed (Coughing)
    3.    Deep breaths & sighs promote re-expansion
    4.    After surgery/Other conditions, Coughing, deep breathing, sustained maximal respiration