Saturday, January 4, 2014

Lungs and gas exchange

Lungs and gas exchange

The primary function of the lungs is to provide oxygen to the tissues and remove carbon dioxide to outside. Respiration includes two phases:  (i) inspiration  (ii) expiration
Inspiration means supply of oxygen from the atmosphere to the tissue space through respiratory tract and blood.
Expiration means transport of carbon dioxide from the tissue space to atmosphere through respiratory tract and blood.
The respiratory system is made of                                          
(i)                 Lungs: gas exchanging organ                         
(ii)               Chest wall & respiratory muscle→ increase & decrease the size of the thoracic cavity
(iii)              Areas in the brain → control the muscles

Alveoli AND Respiratory Zone

      Polyhedral in shape and clustered like units of honeycomb.
      ~ 300 million air sacs (alveoli).

     Large surface area (60–80 m2).
     Each alveolus is 1 cell layer thick.
      Total air barrier is 2 cells across (2 mm).
      Respiratory Zone: Region of gas exchange between air  and blood.
     Includes respiratory bronchioles and alveolar sacs.
     Must contain alveoli.

Gas Exchange in Lungs

Gas Exchange in Lungs

How tissue gets oxygen and release carbon dioxide
How Red Cells carry oxygen :
Partial Pressures of Gases in Blood
When a liquid or gas (blood and alveolar air) are at equilibrium, the amount of gas dissolved in fluid reaches a maximum value (Henry’s Law)
Depends upon:
Solubility of gas in the fluid
Temperature of the fluid
Partial pressure of the gas
[Gas] dissolved in a fluid depends directly on its partial pressure in the gas mixture
How tissue gets oxygen and release carbon dioxide
         At normal P02 arterial blood is about 100 mm Hg.
         P02 level in the systemic veins is about 40 mm Hg.
         PC02 is 46 mm Hg in the systemic veins.
Gas Exchange in Lungs

Excretory System and Urinary system includes

Excretory System 

Kidneys are the excretory organ of our body. These are the major component of urinary system 

Urinary system includes                                          

  • The paired kidneys lie on either side of the vertebral column below the diaphragm and live. Each adult kidney weighs about 160 g and is about 11 cm long and 5 to 7 cm wide. Kidney is formation of urine. 
  • Ureters transport of urine from kidneys to urinary bladder  
  • Urinary bladder…reservoir of urine  
  • Urethra...passage of urine from urinary bladder to outside (In females, the urethra is 4 cm (1.5  in) long In males, the urethra is about 20 cm (8 in) longEach kidney contains about one million Nephrones which are the structural & functional unit of kidneys.)

How kidneys clean blood

The primary function of the kidneys is regulation of the extracellular fluid (plasma and interstitial fluid) environment in the body. Accomplished by the formation of Urine.

Kidney Functions

1. The volume of blood plasma (and thus contribute significantly to the regulation of blood pressure);
2. The concentration of waste products in the blood;
3. The concentration of electrolytes (Na+, K+,HCO3and other ions) in the plasma; and
4. The pH of plasma

Excretion of excess unnecessary substances & metabolic waste products Osmoregulation Regulation of      

(i) water & electrolyte balances
(ii) acid-base balances
(iii) blood pressure
(iv) red cell production

How kidneys clean blood

Kidneys clean blood by filtering it. They filter all our blood 300 times a day. The filtering is done by over a million tubes packed into each kidney. These tubes are called nephrones.  Some people’s kidneys are not very good at filtering blood. Kidney machines help by filtering blood for them.

Digestion and food sources

The process by which food is converted into substances that can be absorbed and assimilated by the body. Mechanical & chemical breakdown of food into nutrients are called digestion.
Four main macromolecules in food: nucleic acids, proteins, fats, and carbohydrates are broken down into smaller molecules of nucleotides, amino acids, fatty acids and glycerol, and simple sugars. Being absorbed important minerals, vitamins, and water are also extract from food during the process of digestion.

Food Sources

Biologists categorize animals into three groups based on their food source.

  • Herbivores obtain all food from plants. Examples: cows, horses, and nearly all rodents.
  • Carnivores obtain all food from meat. Examples: cats, eagles, wolves, and frogs.
  • Omnivores obtain food from both plants and meat.      
Examples: humans and bears. An animal’s digestive system is specifically suited to processing food obtained from its food source. For example, herbivores’ digestive systems are equipped to break down plant material, and carnivores’ are not.