1) Storage - the stomach allows a meal to be consumed and the materials released incrementally into the duodenum for digestion. It may take up to four hours for food from a complete meal to clear the stomach. 
2) Chemical digestion - pepsin begins the process of protein digestion cleaving large polypeptides into shorter chains . 
3) Mechanical digestion - the churning action of the muscularis causes liquefaction and mixing of the contents to produce acid chyme. 
4) Some absorption - water, electrolytes, monosaccharides, and fat soluble molecules including alcohol are all absorbed in the stomach to some degree.

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.

Cardiac Output:

Minute Volume = Heart Rate X Stroke Volume

Heart rate, HR at rest = 65 to 85 bpm  

Each heartbeat at rest takes about .8 sec. of which .4 sec. is quiescent period.

Stroke volume, SV at rest = 60 to 70 ml.

Heart can increase both rate and volume with exercise. Rate increase is limited due to necessity of minimum ventricular diastolic period for filling. Upper limit is usually put at about 220 bpm. Maximum heart rate calculations are usually below 200. Target heart rates for anaerobic threshold are about 85 to 95% of maximum.

Terms:

End Diastolic Volume, EDV - the maximum volume of the ventricles achieved at the end of ventricular diastole. This is the amount of blood the heart has available to pump. If this volume increases the cardiac output increases in a healthy heart.

End Systolic Volume, ESV - the minimum volume remaining in the ventricle after its systole. If this volume increases it means less blood has been pumped and the cardiac output is less.

EDV - ESV = SV

SV / EDV = Ejection Fraction The ejection fraction is normally around 50% at rest and will increase during strenuous exercise in a healthy heart. Well trained athletes may have ejection fractions approaching 70% in the most strenuous exercise.

Isovolumetric Contraction Phase - a brief period at the beginning of ventricular systole when all valves are closed and ventricular volume remains constant. Pressure has risen enough in the ventricle to close the AV valves but not enough to open the semilunar valves and cause ejection of blood. 

Isovolumetric Relaxation Phase - a brief period at the beginning of ventricular diastole when all valves are closed and ventricular volume is constant. Pressure in the ventricle has lowered producing closure of the semilunar valves but not opening the AV valves to begin pulling blood into the ventricle.

Dicrotic Notch - the small increase in pressure of the aorta or other artery seen when recording a pulse wave. This occurs as blood is briefly pulled back toward the ventricle at the beginning of diastole thus closing the semilunar valves.

Preload - This is the pressure at the end of ventricular diastole, at the beginning of ventricular systole. It is proportional to the End Diastolic Volume (EDV), i.e. as the EDV increases so does the preload of the heart. Factors which increase the preload are: increased total blood volume, increased venous tone and venous return, increased atrial contraction, and the skeletal muscular pump.

Afterload - This is the impedence against which the left ventricle must eject blood, and it is roughly proportional to the End Systolic Volume (ESV). When the peripheral resistance increases so does the ESV and the afterload of the heart. 

The importance of these parameters are as a measure of efficiency of the heart, which increases as the difference between preload and afterload increases

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.

Events in gastric function:

1) Signals from vagus nerve begin gastric secretion in cephalic phase.

2) Physical contact by food triggers release of pepsinogen and H⁺ in gastric phase.

3) Muscle contraction churns and liquefies chyme and builds pressure toward pyloric sphincter.

4) Gastrin is released into the blood by cells in the pylorus. Gastrin reinforces the other stimuli and acts as a positive feedback mechanism for secretion and motility.

5) The intestinal phase begins when acid chyme enters the duodenum. First more gastrin secretion causes more acid secretion and motility in the stomach.

6) Low pH inhibits gastrin secretion and causes the release of enterogastrones such as GIP into the blood, and causes the enterogastric reflex. These events stop stomach emptying and allow time for digestion in the duodenum before gastrin release again stimulates the stomach.

White Blood Cells (leukocytes)

White blood cells

• are much less numerous than red (the ratio between the two is around 1:700),
• have nuclei,
• participate in protecting the body from infection,
• consist of lymphocytes and monocytes with relatively clear cytoplasm, and three types of granulocytes, whose cytoplasm is filled with granules.

Lymphocytes: There are several kinds of lymphocytes, each with different functions to perform , 25% of wbc The most common types of lymphocytes are

• B lymphocytes ("B cells"). These are responsible for making antibodies.
• T lymphocytes ("T cells"). There are several subsets of these:
  • inflammatory T cells that recruit macrophages and neutrophils to the site of infection or other tissue damage
  • cytotoxic T lymphocytes (CTLs) that kill virus-infected and, perhaps, tumor cells
  • helper T cells that enhance the production of antibodies by B cells

Although bone marrow is the ultimate source of lymphocytes, the lymphocytes that will become T cells migrate from the bone marrow to the thymus where they mature. Both B cells and T cells also take up residence in lymph nodes, the spleen and other tissues where they

• encounter antigens;
• continue to divide by mitosis;
• mature into fully functional cells.

Monocytes : also originate in marrow, spend up to 20 days in the circulation, then travel to the tissues where they become macrophages. Macrophages are the most important phagocyte outside the circulation. Monocytes are about 9% of normal wbc count

Macrophages are large, phagocytic cells that engulf

• foreign material (antigens) that enter the body
• dead and dying cells of the body.

Neutrophils

The most abundant of the WBCs. about 65% of normal white count  These cells spend 8 to 10 days in the circulation making their way to sites of infection etc  Neutrophils squeeze through the capillary walls and into infected tissue where they kill the invaders (e.g., bacteria) and then engulf the remnants by phagocytosis. They have two types of granules: the most numerous are specific granules which contain bactericidal agents such as lysozyme; the azurophilic granules are lysosomes containing peroxidase and other enzymes

Eosinophils : The number of eosinophils in the blood is normally quite low (0–450/µl). However, their numbers increase sharply in certain diseases, especially infections by parasitic worms. Eosinophils are cytotoxic, releasing the contents of their granules on the invader.

Basophils : rare except during infections where these cells mediate inflammation by secreting histamine and heparan sulfate (related to the anticoagulant heparin). Histamine makes blood vessels permeable and heparin inhibits blood clotting. Basophils are functionally related to mast cells.  . The mediators released by basophils also play an important part in some allergic responses such as hay fever and an anaphylactic response to insect stings.

Thrombocytes (platelets):

Thrombocytes are cellular derivatives from megakaryocytes which contain factors responsible for the intrinsic clotting mechanism. They represent fragmented cells  which contain residual organelles including rough endoplasmic reticulum and Golgi apparati. They are only 2-microns in diameter, are seen in peripheral blood either singly or, often, in clusters, and have a lifespan of 10 days.