B2: Organisation Flashcards
What is a cell, a tissue, an organ and an organ system?
+ Cell: The smallest unit of a living organism
+ Tissue: A group of cells with a similar function & structure
+ Organ: A group of tissues that work together to perform a function
+ Organ System: A series of organs that work together to perform a function
In what order do the Organs of the digestive system connect (from food intake)?
Mouth → Oesophagus → Stomach → Small Intestine → Large Intestine → Anus → Rectum
Other Organs that food doesn’t pass through:
Salivary Glands, Liver, Gall bladder, Pancreas
What are the functions of each of the organs in the digestive system?
+ Mouth: To break up food
+ Salivary Glands: To produce Amylase & other digestive enzymes
+ Oesophagus: To push food down to the stomach
+ Liver: To produce Bile & filter blood (among other things)
+ Gall Bladder: To store Bile
+ Stomach: To churn & digest food with acid
+ Pancreas: To produce digestive enzymes
+ Small intestine: To digest food & absorb soluble food molecules, like nutrients
+ Large Intestine: To absorb water & produce faeces
+ Rectum: To store faeces until excretion
+ Anus: To excrete faeces
What are Enzymes?
Enzymes are Proteins that act as biological catalysts within the body, reducing activation energies for metabolic reactions.
What is the ‘Lock & Key’ Theory?
The Lock and key theory is a way of explaining enzyme activity, and it dictates that every enzyme has an active site that matches perfectly in shape to a specific substrate.
Like a lock for a key, each enzyme can only interact with the one substrate whose reaction it is designed to catalyse.
What are the three Main Enzymes for digestion, what do they do, where are they produced and where do they Act?
\+ Amylase > Breaks Carbohydrates down into simple sugars > Produced by the salivary glands & Pancreas > Used in the mouth & small intestine \+ Protease > Breaks proteins down into amino acids > Produced by the stomach & pancreas > Used in the stomach & small intestine \+ Lipase > Breaks lipids down into glycerol & fatty acids > Produced by the pancreas > Used in the small intestine
What are the two factors that primarily affect enzyme Activity, and in what way do they affect it?
+ Temperature
> The Higher the temperature of the environment, the more efficiently the enzyme works, to an extent…
> Above a certain temperature, enzymes begin to denature, and the shape of their active sites deform. This means they can no longer catalyse the reaction of their relevant substrate
> The temperature that enzymes work best in before they denature is known as the optimum temperature
+ pH
> Each Enzyme has an optimum pH level that it works best at.
> For example, enzymes that work in the stomach function best at a lower, more acidic, pH
> Outside of their optimum conditions, these enzymes work less effectively, and in extreme pH conditions, they denature
What are the two functions of Bile and where is it produced and stored?
The two functions of Bile:
+ The neutralisation of Stomach Acid
+ The emulsification of lipids
> This increases the surface area of the lipid by turning it into droplets, which allows more Lipase to catalyse its breakdown
Why do we digest food?
+ We digest food to break down large, insoluble food molecules into smaller, soluble food molecules that can be absorbed into the bloodstream via diffusion into the villi
+ These smaller food molecules are used to create new lipids, proteins, carbohydrates
+ Some of the absorbed glucose is also used for respiration
How do we test foods for Proteins, Starch & Sugars?
+ To test for the presence of proteins, use Biuret solution
> If the sample turns purple, protein is present
+ To test for the presence of sugars
> Heat for two minutes, and depending on the concentration of sugar, the solution will turn green, yellow or red
+ To test for the presence of starch, use iodine
> If the sample turns black/blue, starch is present
+ To test for the presence of lipids, use Sudan III or Ethanol
> If a red layer gathers at the top using Sudan III, lipids are present
> If, when shaken with ethanol, the food solution turns cloudy, lipids are present
What are the four main Chambers of the Heart, and how do they work to pump blood?
The four chambers of the heart are arranged in the following arrangement
Right Atrium Left Atrium
Right Ventricle Left Ventricle
+ The atriums fill with blood from the vena cava & pulmonary vein
> The heart pumps the muscles, forcing blood from the atriums into the ventricles
> The blood then pumps again, sending blood in the ventricles to the lungs and around the body through the pulmonary artery & aorta respectively
What are the five main blood Vessels of the Heart, and what do they do?
+ De-oxygenated blood from the rest of the body enters the right atrium through the VENA CAVA
+ This blood is pumped into the right ventricle, and then pumped out into the PULMONARY ARTERY, which leads to the lungs
+ At the lungs, the blood is oxygenated and returned to the heart via the PULMONARY VEIN, which connects to the left atrium
+ The oxygenated blood is pumped from the left atrium into the left ventricle, and is then pumped through to the rest of the body via the AORTA
+ There are also CORONARY ARTERIES that supply oxygenated blood to the heart
How is your heartbeat regulated?
+ The heartbeat is regulated by a group of cells known as the pacemaker, and these regulate your normal resting heart rate
> Electrical, artificial pacemakers can be used to regulate the heart rate in the event of irregularities
Why is the cardiovascular system a double circulatory system?
The cardiovascular system is a double circulatory system because for every circuit of the system, blood passes through the heart twice
How are the lungs structured?
+ The Trachea (or windpipe) splits into two tubes called bronchi, which then split into smaller tubes called bronchioles before finally ending with tiny air sacs called alveoli
+ There are millions of alveoli in the lungs
