Control of processes in the stomach:

The stomach, like the rest of the GI tract, receives input from the autonomic nervous system. Positive stimuli come from the parasympathetic division through the vagus nerve. This stimulates normal secretion and motility of the stomach. Control occurs in several phases:

Cephalic phase stimulates secretion in anticipation of eating to prepare the stomach for reception of food. The secretions from cephalic stimulation are watery and contain little enzyme or acid.

Gastric phase of control begins with a direct response to the contact of food in the stomach and is due to stimulation of pressoreceptors in the stomach lining which result in ACh and histamine release triggered by the vagus nerve. The secretion and motility which result begin to churn and liquefy the chyme and build up pressure in the stomach. Chyme surges forward as a result of muscle contraction but is blocked from entering the duodenum by the pyloric sphincter. A phenomenon call retropulsion occurs in which the chyme surges backward only to be pushed forward once again into the pylorus. The presence of this acid chyme in the pylorus causes the release of a hormone called gastrin into the bloodstream. Gastrin has a positive feedback effect on the motility and acid secretion of the stomach. This causes more churning, more pressure, and eventually some chyme enters the duodenum.

Intestinal phase of stomach control occurs. At first this involves more gastrin secretion from duodenal cells which acts as a "go" signal to enhance the stomach action already occurring. But as more acid chyme enters the duodenum the decreasing pH inhibits gastrin secretion and causes the release of negative or "stop" signals from the duodenum.

These take the form of chemicals called enterogastrones which include GIP (gastric inhibitory peptide). GIP inhibits stomach secretion and motility and allows time for the digestive process to proceed in the duodenum before it receives more chyme. The enterogastric reflex also reduces motility and forcefully closes the pyloric sphincter. Eventually as the chyme is removed, the pH increases and gastrin and the "go" signal resumes and the process occurs all over again. This series of "go" and "stop" signals continues until stomach emptying is complete.

Serum Proteins

Proteins make up 6–8% of the blood. They are about equally divided between serum albumin and a great variety of serum globulins.

After blood is withdrawn from a vein and allowed to clot, the clot slowly shrinks. As it does so, a clear fluid called serum is squeezed out. Thus:

Serum is blood plasma without fibrinogen and other clotting factors.

The serum proteins can be separated by electrophoresis.

• The most prominent of these and the one that moves closest to the positive electrode is serum albumin.
• Serum albumin
  • is made in the liver
  • binds many small molecules for transport through the blood
  • helps maintain the osmotic pressure of the blood
• The other proteins are the various serum globulins.
  • alpha globulins (e.g., the proteins that transport thyroxine and retinol [vitamin A])
  • beta globulins (e.g., the iron-transporting protein transferrin)
  • gamma globulins.
    • Gamma globulins are the least negatively-charged serum proteins. (They are so weakly charged, in fact, that some are swept in the flow of buffer back toward the negative electrode.)
    • Most antibodies are gamma globulins.
    • Therefore gamma globulins become more abundant following infections or immunizations. 

 Acute Obstructive Disorders
 1.    Heimlich maneuver
 2.    Bypass, tracheostomy w/catheter to suck up secretion

An anti-diruetic is a substance that decreases urine volume, and ADH is the primary example of it within the body. ADH is a hormone secreted from the posterior pituitary gland in response to increased plasma osmolarity (i.e., increased ion concentration in the blood), which is generally due to an increased concentration of ions relative to the volume of plasma, or decreased plasma volume.

The increased plasma osmolarity is sensed by osmoreceptors in the hypothalamus, which will stimulate the posterior pituitary gland to release ADH. ADH will then act on the nephrons of the kidneys to cause a decrease in plasma osmolarity and an increase in urine osmolarity.

ADH increases the permeability to water of the distal convoluted tubule and collecting duct, which are normally impermeable to water. This effect causes increased water reabsorption and retention and decreases the volume of urine produced relative to its ion content.

After ADH acts on the nephron to decrease plasma osmolarity (and leads to increased blood volume) and increase urine osmolarity, the osmoreceptors in the hypothalamus will inactivate, and ADH secretion will end. Due to this response, ADH secretion is considered to be a form of negative feedback.

Glomerular filtration

Kidneys receive about 20% of cardiac output , this is called Renal Blood Flow (RBF) which is approximatley 1.1 L of blood. Plasma in this flow is about 625 ml . It is called Renal Plasma Flow (RPF) .
About 20 % of Plasma entering the glomerular capillaries is filtered into the Bowman`s capsule .
Glomerular filtration rate is about 125 ml/min ( which means 7.5 L/hr and thus 180 L/day) This means that the kidney filters about 180 liters of plasma every day.

The urine flow is about 1ml/min ( about 1.5 liter /day) This means that kidney reabsorbs about 178.5 liters every day .

Filtration occurs through the filtration unit , which includes :

1- endothelial cells of glomerular capillaries , which are fenestrated . Fenestrae are quite small so they prevent filtration of blood cells and most of plasma proteins .

2- Glomerular basement membrane : contains proteoglycan that is negatively charged and repels the negatively charged plasma proteins that may pass the fenestrae due to their small molecular weight like albumin . so the membrane plays an important role in impairing filtration of albumin .

3- Epithelial cells of Bowman`s capsule that have podocytes , which interdigitate to form slits .

Many forces drive the glomerular filtration , which are :

1- Hydrostatic pressure of the capillary blood , which favours filtration . It is about 55 mmHg .

2- Oncotic pressure of the plasma proteins in the glomerular capillary ( opposes filtration ) . It is about 30 mm Hg .

3- Hydrostatic pressure of the Bowman`s capsule , which also opposes filtration. It is about 15 mmHg .

The net pressure is as follows :

Hydrostatic pressure of glomerular capillaries - ( Oncotic pressure of glomerular capillaries + Hydrostatic pressure of the Bowman capsule):
55-(35+10)
=55-45
=10 mmHg .

Te glomerular filtration rate does not depend only on the net pressure , but also on an other value , known as filtration coefficient ( Kf) . The later depends on the surface area of the glomerular capillaries and the hydraulic conductivity of the glomerular capillaries.
 

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