Organisation Flashcards
What is a tissue? Give an example
A group of cells with similar structure and function, such as muscle tissue.
What is an organ? Give an example
An organ is a group of different tissues that work together to perform a certain function.
(eg muscle tissue and glandular tissue work together to form the stomach)
What is an organ system?
A group of different organs working together to perform a certain function. Organ systems work together to make organisms.
Why do organisms need organ systems?
To exchange and transport substances needed by the body.
What 2 factors affect the rate at which enzymes catalyse reactions?
Temperature - increases the rate at first but if it gets too high the enzyme denatures
pH - they have an optimal pH, if its too high OR too low, it can denature
How arteries are suited for purpouse
Thick, muscular walls to withstand high pressure
Elastic walls that stretch and recoil to help push blood through the body
How are veins suited for purpouse, why is this needed?
They have valves to prevent backflow of blood. This can happen as its no longer at high pressure and speed.
Wide lumen (the actual tube) to allow low pressure blood to flow
How are capillaries suited for purpouse?
Their walls are only one cell thick so substances can diffuse rapidly from blood to cells and vice versa.
They carry blood very close to individual cells - even faster.
Permeable walls so substances can move through
How is bile released into the small intestine and what does it do? And why
It is secreted by the gall bladder and it neutralises stomach acid. (Optimal pH, prevent damage)
It also emulsifies lipids to increase the surface area for lipase enzymes to act on.
Why does protein digestion begin in the stomach?
An enzyme called pepsin is used to break down proteins, and it works best in the acidic conditions of the stomach.
What are some uses of the products of digestion?
Making new lipids, carbohydrates and proteins.
Some of the glucose used for respiration.
Why does food need to be broken down?
Food molecules are too large to absorb into the bloodstream for delivery to cells.
What does the large intestine do?
Absorbs water and electrolytes.
Forms food waste into faeces and pushes it through to the rectum.
Why is the left ventricle thicker and more muscular?
Needs to pump blood with enough force to reach the entire body, right only has to send it to lungs.
How does the heart’s natural pacemaker work?
Group of cells generate electrical impulses that cause muscles in the heart to contract (beat)
