Gas exchange

6.4.1  Distinguish between ventilation, gas exchange and cell respiration

Ventilation : When air is inhaled into the alveoli  , then exhaled.
Gas exchange : is the diffusion of co2 and o2 between the alveoli adn the capilaries.
Cell respiration : O2 is a reactan for aerobic cell respiration
CO2 is a product of aerobic respiration cell respiration. (The chemical process occurring in the mitochondria where energy is released as ATP)







6.4.2  Explain the need for ventilation system  

• We need ventilation system to get rid of carbon dioxide. to mantain a concentration gradient, always more co2 in blood than alveoli , and always more o2 in alveoli than blood
• Air wouldnt enter o leave our lungs by itself.

http://www.jonbarron.org/article/physiology-respiratory-system






6.4.3 Describe the features of aleveoli that adapt them to gas exchange
-Large surface due to the combined sphercial shape
-is flattened single cell thicknedd of each alveoulus , this prevents the gases from hacing diffuse through more cell layers
-moist inner linging of alveous , this characteristic makes diffucsion more efficient,

http://click4biology.info/c4b/6/hum6.4.htm#one

6.4.4 Draw and label a diagram of the ventilation system , including trachea lungs, bronchi , bronchioles and alveoli

6.4.5 Explain the mechanism of ventilation of the lungs in terms of volume and preassure changes caused by the internal and external intercostal muscle, the diaphragm and abdominal muscles.

 Inhaling : The external intercostal muscles contract , moving the ribcage in and out. The diaphragm contracts moving down .(increasing the volume of the thorax)  The preeasuure of the thorax drops below atmospheric pressure.
Exhaling : The internal intercostal muscles contract moving the ribcage down and in. The abdominal muscle also contract pushing the diaphragm up.The movements decrease the volume of the thorax. The pressure condition is exactly the opposite when we inhale.

Digestion

6.1.1 Explain why digestion of large molecules is essential 
Basically we need to digest large molecules because they are too large to pass across any cell membrane. As the image shows we make the molecules " our own" in order to be digested.

source: http://click4biology.info/c4b/6/hum6.1.htm#one


6.1.2 Explain the need for enzymes in digestion

-Enzymes are protein molecules which act as catysts for reactions.

 -As we can see in the graph , the need of enzymes in digestion is essential. It reduces the activation energy that a normal reaction would need, obtainig the same product.

-The need of energy in order to digest without enzymes is ilustrated in the graph. There is a big gap between the reaction without enzymes and the reaction with enzymes.  

6.1.3 State the source , substrate, products an optimum PH conditions for one amylase, one protease and one lipase: 

 source : salivary glands
  substrate : amylose (starch)
  product: maltose and glucose (sugar)
  pH : neutral (pH 7)

 Source : pancreas cells
 Substrate: Lipids
 Porducts : Glycerol and fatty acids
 pH : neutral (pH 7)

Source: stomach cells 

Substrate : proteins 

Products: aminoacids 

pH: 3 (acid)

http://www.bbc.co.uk/schools/ks3bitesize/science/organisms_behaviour_health/diet_drugs/revise5.shtml 

6.1.4 Draw and label a diagram of the digestive system 

   http://click4biology.info/c4b/6/hum6.1.htm#three

6.1.5 Outline the function of the stomach , small intestine and large intestine 

a)Stomach:  When you swallow your food is forced down yo your stomach through the esophagus. The stomach helds your food for a period of time. Also in the stomach is where the digestion of protein begins. 

• the acid that is in your stomach activates the pesin and kill bacterias that could cause food poisoning.

http://academic.brooklyn.cuny.edu/biology/bio4fv/page/stomach.html 

b)Small Intestine : In the small intestine is where the food is finally digested. The inner wall of the intestine is formed by small structures called Villi (shown in the image ) which is covered by another structure called. 

Villies make absorption possible, they absorb food molecules so they can be assimilated and become part of the tissues of the body.

The microvilli increases the surface for the absorption process.

http://www.daviddarling.info/encyclopedia/S/small_intestine.html

Large intestine: Basically the primary function of the large itnestine is to absorve water. But the large intestine also works as refuge for bascterias including escherichia coli. We provide nutrients water and an enviroment for them while they synthesize vitamin K for us.

6.1.6 Distinguish between absorption and assimilation 

a) absorption is when the nutrients are absorbed into the circulatory system 

b) When the nutrients travel to different tissues in the ciruclatory system , the nutrients are absorbed by the  tissue cells , and become part of the body cells. This is called assimilation

6.1.7 Explain how the structure if the villus is related to its role in absorption and transport of the products of digestion  

The structure of the villi is specific. The villus are structures present in the smaill intestine that increase the surface area in order to absorb the molecules.

The villi surface is covered with microvilli, which increases the surface area .

Also the villi has a one cell layer so food can be absorbed easily . The clood capilarries are really close to the one cell layer making it easy for the molecules to pass to the circulatory system.

http://www.ibguides.com/biology/notes/digestion