CNS PROTECTION

- Bones of the Skull       Frontal, Temporal, Parietal, Sphenoid, Occipital

- Cranial Meninges         Dura mater, Arachnoid Space, Pia mater

- Cerebrospinal Fluid

Secreted by Chroid Plexi in Ventricles

Circulation through ventricles and central canal

Lateral and Median apertures from the 4th ventricle into the subarachnoid space

Arachnoid villi of the superior sagittal sinus return CSF to the venous circulation

Hydrocephalic Condition, blockage of the mesencephalic aqueduct, backup of CSF, Insertion of a shunt to drain the excess CSF

Carbon Dioxide Transport

Carbon dioxide (CO₂) combines with water forming carbonic acid, which dissociates into a hydrogen ion (H⁺) and a bicarbonate ions:

CO₂ + H₂O ↔ H₂CO₃ ↔ H⁺ + HCO₃⁻

95% of the CO₂ generated in the tissues is carried in the red blood cells:

• It probably enters (and leaves) the cell by diffusing through transmembrane channels in the plasma membrane. (One of the proteins that forms the channel is the D antigen that is the most important factor in the Rh system of blood groups.)
• Once inside, about one-half of the CO₂ is directly bound to hemoglobin (at a site different from the one that binds oxygen).
• The rest is converted — following the equation above — by the enzyme carbonic anhydrase into
  • bicarbonate ions that diffuse back out into the plasma and
  • hydrogen ions (H⁺) that bind to the protein portion of the hemoglobin (thus having no effect on pH).

Only about 5% of the CO₂ generated in the tissues dissolves directly in the plasma. (A good thing, too: if all the CO₂ we make were carried this way, the pH of the blood would drop from its normal 7.4 to an instantly-fatal 4.5!)

When the red cells reach the lungs, these reactions are reversed and CO₂ is released to the air of the alveoli.

Proteinuria—Protein content in urine, often due to leaky or damaged glomeruli.

Oliguria—An abnormally small amount of urine, often due to shock or kidney damage.

Polyuria—An abnormally large amount of urine, often caused by diabetes.

Dysuria—Painful or uncomfortable urination, often from urinary tract infections.

Hematuria—Red blood cells in urine, from infection or injury.

Glycosuria—Glucose in urine, due to excess plasma glucose in diabetes, beyond the amount able to be reabsorbed in the proximal convoluted tubule.

Properties of cardiac muscle

Cardiac muscle is a striated muscle like the skeletal muscle , but it is different from the skeletal muscle in being involuntary and syncytial .

Syncytium means that cardiac muscle cells are able to excite and contract together due to the presence of gap junctions between adjacent cardiac cells.

Cardiac muscle has four properties , due to which the heart is able to fulfill its function as a pumping organ. Studying and understanding these properties is essential for students to understand the cardiac physiology as a whole.

1. Rhythmicity ( Chronotropism )
2. Excitability ( Bathmotropism ) 
3. Conductivity
4. Contractility

Physiology - science that describes how organisms FUNCTION and survive in continually changing environments  

Cells, cytoplasm, and organelles:

• Cytoplasm consists of a gelatinous solution and contains microtubules (which serve as a cell's cytoskeleton) and organelles

• Cells also contain a nucleus within which is found DNA (deoxyribonucleic acid) in the form of chromosomes plus nucleoli (within which ribosomes are formed)

• Organelles include:

1. Endoplasmic reticulum : 2 forms: smooth and rough; the surface of rough ER is coated with ribosomes; the surface of smooth ER is not , Functions include: mechanical support, synthesis (especially proteins by rough ER), and transport
2. Golgi complex consists of a series of flattened sacs (or cisternae) functions include: synthesis (of substances likes phospholipids), packaging of materials for transport (in vesicles), and production of lysosomes
3. Lysosome : membrane-enclosed spheres that contain powerful digestive enzymes , functions include destruction of damaged cells & digestion of phagocytosed materials
4.  Mitochondria : have double-membrane: outer membrane & highly convoluted inner membrane
   1. inner membrane has folds or shelf-like structures called cristae that contain elementary particles; these particles contain enzymes important in ATP production
   2. primary function is production of adenosine triphosphate (ATP)
5. Ribosome-:composed of rRNA (ribosomal RNA) & protein , primary function is to produce proteins
6. Centrioles :paired cylindrical structures located near the nucleas , play an important role in cell division
7. Flagella & cilia - hair-like projections from some human cells
   1. cilia are relatively short & numerous (e.g., those lining trachea)
   2. a flagellum is relatively long and there's typically just one (e.g., sperm)

• • Villi  Projections of cell membrane that serve to increase surface area of a cell (which is important, for example, for cells that line the intestine)