Factors , affecting glomerular filtration rate :

 Factors that may influence the different pressure forces , or the filtration coefficient will affect the glomerular filtration rate . 
 
1. Dehydration : Causes decrease hydrostatic pressure , and thus decreases GFR
2- Liver diseases that may decrease the plasma proteins and decrease the oncotic pressure , and thus increases glomerular filtration rate .
3- Sympathetic stimulation : will decrease the diameter of afferent arteriole and thus decreases glomerular filtration rate.
4- Renal diseases : Nephrotic syndrome for example decreases the number of working nephrons and thus decreases the filtration coefficient and thus decreases the glomerular filtration rate.
Glomerulonephritis will causes thickening of the glomerular basement membrane and thus decreases the glomerular filtration rate by decreasing the filtration coefficient too.

Bile - produced in the liver and stored in the gallbladder, released in response to CCK . Bile salts (salts of cholic acid) act to emulsify fats, i.e. to split them so that they can mix with water and be acted on by lipase.

Pancreatic juice: Lipase - splits fats into glycerol and fatty acids. Trypsin, and chymotrypsin - protease enzymes which break polypeptides into dipeptides. Carboxypeptidase - splits dipeptide into amino acids. Bicarbonate - neutralizes acid. Amylase - splits polysaccharides into shorter chains and disaccharides.

Intestinal enzymes (brush border enzymes): Aminopeptidase and carboxypeptidase - split dipeptides into amino acids. Sucrase, lactase, maltase - break disaccharides into monosaccharides. Enterokinase - activates trypsinogen to produce trypsin. Trypsin then activates the precursors of chymotrypsin and carboxypeptidase. Other carbohydrases: dextrinase and glucoamylase. These are of minor importance.

Cell, or Plasma, membrane

• Structure - 2 primary building blocks include

protein (about 60% of the membrane) and lipid, or

fat (about 40% of the membrane).

The primary lipid is called phospholipids, and molecules of phospholipid form a 'phospholipid bilayer' (two layers of phospholipid molecules). This bilayer forms because the two 'ends' of phospholipid molecules have very different characteristics: one end is polar (or hydrophilic) and one (the hydrocarbon tails below) is non-polar (or hydrophobic):

• Functions include:
  • supporting and retaining the cytoplasm
  • being a selective barrier .
  • transport
  • communication (via receptors)

Gonadotropin-releasing hormone (GnRH)

GnRH is a peptide of 10 amino acids. Its secretion at the onset of puberty triggers sexual development.

Primary Effects

FSH and LH Relaese

Secondary Effects

Increases estrogen and progesterone (in females)

testosterone Relaese (in males)

Growth hormone-releasing hormone (GHRH)

GHRH is a mixture of two peptides, one containing 40 amino acids, the other 44.  GHRH stimulates cells in the anterior lobe of the pituitary to secrete growth hormone (GH).

Corticotropin-releasing hormone (CRH)

CRH is a peptide of 41 amino acids. Its acts on cells in the anterior lobe of the pituitary to release adrenocorticotropic hormone (ACTH) CRH is also synthesized by the placenta and seems to determine the duration of pregnancy.  It may also play a role in keeping the T cells of the mother from mounting an immune attack against the fetus

Somatostatin

Somatostatin is a mixture of two peptides, one of 14 amino acids, the other of 28. Somatostatin acts on the anterior lobe of the pituitary to

• inhibit the release of growth hormone (GH)
• inhibit the release of thyroid-stimulating hormone (TSH)

Somatostatin is also secreted by cells in the pancreas and in the intestine where it inhibits the secretion of a variety of other hormones.

Antidiuretic hormone (ADH) and Oxytocin

These peptides are released from the posterior lobe of the pituitary

Lung volumes and capacities: 
I. Lung`s volumes
1. Tidal volume (TV) : is the volume of air m which is inspired and expired during one quiet breathing . It equals to 500 ml.
 

2. Inspiratory reserve volume (IRV) : The volume of air that could be inspired over and beyond the tidal volume. It equals to 3000 ml of air.
 

3. Expiratory reserve volume (ERV) : A volume of air that could be forcefully expired after the end of quiet tidal volume. It is about 1100 ml of air.
 

4. Residual volume (RV) : the extra volume of air that may remain in the lung after the forceful expiration . It is about 1200 ml of air.
 

5. Minute volume : the volume of air that is inspired or expired within one minute. It is equal to multiplying of respiratory rate by tidal volume = 12X500= 6000 ml.
It is in female  lesser than that in male.
II. Lung`s capacities :
1. Inspiratory capacity: TV + IRV
2. Vital capacity : TV+IRV+ERV
3. Total lung capacity : TV+IRV+ERV+RV

Heart is a hollow muscular organ , that is located in the middle mediastinum  between the two bony structures of the sternum and the vertebral column ( a very important location for applying Cardiopulmonary Resuscitation - CPR- ) .
It has a shape of clenched fist , which weighs about 300 grams ( with mild variation between male and female ).
  Heart has an apex that is anteriorly , inferiorly , and leftward oriented , and a base , that is posteriorly , superiorly and rightward oriented   .
 In addition to its apex and base the heart has anterior , posterior and left surfaces.
 
 The wall of the heart is composed of three layers :
 
1. Endocardium : The innermost layer , which lines the heart chambers and is in direct contact with the blood . It is composed of endothelial cells that are similar to those , that line the blood vessels , and of connective tissue too. 
 Endocardium has a smooth surface that prevents blood clotting, as it ensures laminar blood flow .

 Clinical Physiology 
 Endocarditis is the inflammation of the endocardium , which is resistant to antibiotic treatment and difficult to cure.Endocarditis usually involves heart valves and chordae tendineae too.

 2. Myocardium  : The middle layer of the cardiac wall . It is the thickest among the three layers , and is composed of two types of cardiac muscles :
a. contractile muscle cells (form about 98-99% of the cardiac muscle ) .
 b- non-contractile muscle cells ( form about 1-2 % of the cardiac muscles and are the cells that form excitatory-conductive system of the heart).
 The cardiac muscle cells are similar to the skeletal muscles in that they are striated , but similar to the smooth muscles in being involuntary and connected to each others via gap junctions , that facilitate conduction of electrical potential from one cell to the others. Desmosomes adhere cardiac muscle cells to each others .

 3- Epicardium :  is the outermost and protective layer of the heart . It is composed of connective tissue , and form the inner layer of the pericardium ( visceral pericardium - see bellow).

 Pericardium: 
The heart is surrounded by a fluid-fill sac , which is known as pericardium . Pericardium is composed of two layers ( doubled layer membrane ) , between which a fluid-fill pericardial cavity exist .

 The outer layer is called fibrous pericardium , while the inner layer is called serous pericardium , which is subdivided into parietal pericardium and visceral pericardium . The visceral pericardium is the previously mentioned outermost layer of heart ( epicardium) .
Pericardial sac plays an important role in protection of heart from external hazards and infections , as it fixes the heart and limits its motion. It also prevents excessive dilation of the heart.

Clinical physiology: 

When there is excessive fluid in the pericardial cavity as a result of pericardial effusion , a cardiac tamponade will develop . cardiac tamponade means compression of the heart within the pericardial sac , which will prevent the relaxation of the heart ( heart will not be able to fully expand ) , and thus the circulating blood volume will be decreased (obstructive shock) . This is a life threatening situation which has to be urgently cured by  pericardiocentesis . 

Chambers of the heart : 

Heart has four chambers : two atria and two ventricles . The two right and left atria are separated from the two ventricles by the fibrous skeleton , which involves the right ( tricuspid ) and left ( bicuspid ) valves. Right and left atria are separated from each other by the interatrial  septum .
The two ventricles are separated by the interventricular septum.Interventricular septum is muscular in its lower thick part and fibrous in its upper thin part.
The two atria holds the blood returning from the veins and empty it only in a given right moment into the ventricles. Ventricles pump the blood into the arteries . 

Heart valves : 

There are four valves in the heart : Two atrioventricular valves and two semi-lunar valves:
1. Atrioventricular ( AV ) valves: These valves are found between the atria and ventricles , depending on the number of  the leaflets , the right atrioventricular valve is also called tricuspid valve (has three leaflets ) , while the left one is called bicuspid valve (has two leaflets ) . The shape of the bicuspid valve is similar to the mitre of bishop , so it is also called the mitral valve.
The leaflets of the valves are attached to fibrous threads (composed of collagen fibers ) , known as chordae tendineae , which from their side are attached to papillary muscles in the ventricles. These valves prevent backward flow of blood from ventricles during the systole. 

2. Semi-lunar valves : 

These valves are located on the base of the arteries ( aorta and pulmonary artery ) . They prevent the backward flow of blood from the arteries into ventricles.
The structure of the semilunar valves is quite different from that of the AV valves , as they have crescent-shaped cusps that do not have chorda tendinea , instead these cusps are like pockets which are filled of blood when it returns to the ventricles from the lumen of arteries during the diastole  , so they get closed and prevent the backward flow of blood.