Heart sounds

Heart sounds are a result of beating heart and resultant blood flow . that could be detected by a stethoscope during auscultation . Auscultation is a part of physical examination that doctors have to practice them perfectly.
Before discussion the origin and nature of the heart sounds we have to distinguish between the heart sounds and hurt murmurs. Heart murmurs are pathological noises that results from abnormal blood flow in the heart or blood vessels.
Physiologically , blood flow has a laminar pattern , which means that blood flows in form of layers , where the central layer is the most rapid . Laminar blood flow could be turned into turbulent one .

Turbulent blood flow is a result of stenotic ( narrowed ) valves or blood vessels , insufficient valves , roughened vessels` wall or endocardium ,  and many diseases . The turbulent blood flow causes noisy murmurs inside or outside the heart.

Heart sounds ( especially first and second sounds ) are mainly a result of closure of the valves of the heart . While the third sound is a result of vibration of ventricular wall and the leaflets of the opened AV valves after rapid inflow of blood from the atria to ventricles . 

Third heart sound is physiologic in children but pathological in adults.

The four heart sound is a result of the atrial systole and vibration of the AV valves , due to blood rush during atrial systole . It is inaudible neither in adults nor in children . It is just detectable by the phonocardiogram .

Characteristic of heart sounds :

1. First heart sound  (S1 , lub ) : a soft and low pitch sound, caused by closure of AV valves.Usually has two components ( M1( mitral ) and T1 ( tricuspid ). Normally M1 preceads T1.

2. Second heart sound ( S2 , dub) : sharp and high pitch sound . caused by closure of semilunar valves. It also has two components A2 ( aortic) and P2 ( pulmonary) . A2 preceads P2.

3. Third heart sound (S3) : low pitched sound.

4. Fourth heart sound ( S4) very low pitched sound.

As we notice : the first three sounds are related to ventricular activity , while the fourth heart sound is related to atrial activity.
Closure of valves is not the direct cause for heart sounds , but sharp blocking of blood of backward returning of blood by the closing valve is the direct cause.
 

The pancreas

The pancreas consists of clusters if endocrine cells (the islets of Langerhans) and exocrine cells whose secretions drain into the duodenum.

Pancreatic fluid contains:

• sodium bicarbonate (NaHCO₃). This neutralizes the acidity of the fluid arriving from the stomach raising its pH to about 8.
• pancreatic amylase. This enzyme hydrolyzes starch into a mixture of maltose and glucose.
• pancreatic lipase. The enzyme hydrolyzes ingested fats into a mixture of fatty acids and monoglycerides. Its action is enhanced by the detergent effect of bile.
• 4 zymogens— proteins that are precursors to active proteases. These are immediately converted into the active proteolytic enzymes:
  • trypsin. Trypsin cleaves peptide bonds on the C-terminal side of arginines and lysines.
  • chymotrypsin. Chymotrypsin cuts on the C-terminal side of tyrosine, phenylalanine, and tryptophan residues (the same bonds as pepsin, whose action ceases when the NaHCO₃ raises the pH of the intestinal contents).
  • elastase. Elastase cuts peptide bonds next to small, uncharged side chains such as those of alanine and serine.
  • carboxypeptidase. This enzyme removes, one by one, the amino acids at the C-terminal of peptides.
• nucleases. These hydrolyze ingested nucleic acids (RNA and DNA) into their component nucleotides.

The secretion of pancreatic fluid is controlled by two hormones:

• secretin, which mainly affects the release of sodium bicarbonate, and
• cholecystokinin (CCK), which stimulates the release of the digestive enzymes.

Asthma = Reversible Bronchioconstruction 4%-5% of population
    Extrinsic / Atopic = Allergic, inherited (familia), chromosome 11
    IgE, Chemical Mediators of inflammation
    
a.    Intrinsic = Negative for Allergy, Normal IgE, Negative Allergic Tests

    Nucleotide Imbalance cAMP/cGMP: cAMP = Inhibits mediator release, cGMP = Facilitates mediator release
b.    Intolerance to Asprin (Triad Asthma)
c.    Nasal Polyps & Asthma

d.    Treatment cause, Symptoms in Acute Asthma
    1.    Bronchial dilators
    2.    steroids edema from Inflamation
    3.    Bronchiohygene to prevent Secondary Infection, (Remove Excess Mucus)
    4.    Education

GENERAL SOMATIC AFFERENT (GSA) PATHWAYS FROM THE BODY

Pain and Temperature

Pain and temperature information from general somatic receptors is conducted over small-diameter (type A delta and type C) GSA fibers of the spinal nerves into the posterior horn of the spinal cord gray matter .

Fast and Slow Pain

Fast pain, often called sharp or pricking pain, is usually conducted to the CNS over type A delta fibers.

Slow pain, often called burning pain, is conducted to the CNS over smaller-diameter type C fibers.

Touch and Pressure

Touch can be subjectively described as discriminating or crude.

Discriminating (epicritic) touch implies an awareness of an object's shape, texture, three-dimensional qualities, and other fine points. Ability to recognize familiar objects simply by tactile manipulation.

The conscious awareness of body position and movement is called the kinesthetic sens

Crude (protopathic) touch,  lacks the fine discrimination described above and doesn't generally give enough information to the brain to enable it to recognize a familiar object by touch alone.

Subconscious Proprioception

Most of the subconscious proprioceptive input is shunted to the cerebellum.

Posterior Funiculus Injury

Certain clinical signs are associated with injury to the dorsal columns.

 As might be expected, these are generally caused by impairment to the kinesthetic sense and discriminating touch and pressure pathways.

 They include

 (1) the inability to recognize limb position,

 (2) as­tereognosis,

 (3) loss of two-point discrimination,

 (4) loss of vibratory sense, and

 (5) a positive Romberg sign.

Astereognosis is the inability to recognize familiar objects by touch alone. When asked to stand erect with feet together and eyes closed, a person with dorsal column damage may sway and fall. This is a posi­tive Romberg sign.

The Parathyroid Glands

The parathyroid glands are 4 tiny structures embedded in the rear surface of the thyroid gland. They secrete parathyroid hormone (PTH) a polypeptide of 84 amino acids. PTH increases the concentration of Ca²⁺ in the blood in three ways. PTH promotes

• release of Ca²⁺ from the huge reservoir in the bones. (99% of the calcium in the body is incorporated in our bones.)
• reabsorption of Ca²⁺ from the fluid in the tubules in the kidneys
• absorption of Ca²⁺ from the contents of the intestine (this action is mediated by calcitriol, the active form of vitamin D.)

PTH also regulates the level of phosphate in the blood. Secretion of PTH reduces the efficiency with which phosphate is reclaimed in the proximal tubules of the kidney causing a drop in the phosphate concentration of the blood.

Hyperparathyroidism

Elevate the level of PTH causing a rise in the level of blood Ca²⁺ .Calcium may be withdrawn from the bones that they become brittle and break.

 Patients with this disorder have high levels of Ca²⁺ in their blood and excrete small amounts of Ca²⁺ in their urine. This causes hyperparathyroidism.

Hypoparathyroidism

This disorder have low levels of Ca²⁺ in their blood and excrete large amounts of Ca²⁺ in their urine.

Exchange of gases:

• External respiration:
  • exchange of O2 & CO2 between external environment & the cells of the body
  • efficient because alveoli and capillaries have very thin walls & are very abundant (your lungs have about 300 million alveoli with a total surface area of about 75 square meters)

• Internal respiration - intracellular use of O2 to make ATP
• occurs by simple diffusion along partial pressure gradients