B5 - The Living Body Flashcards
Describe the two-stage process of starch digestion. Name the enzyme involved.
Through carbohydrase in the mouth, starch is broken down into a compound in the mouth called maltose. Later, in the small intestines, this maltose is broken down (again, by carbohydrase) into glucose.
How does bile help to digest fats in the small intestine?
In the small intestine, it breaks down the fat molecules into smaller droplets. This means that there is a greater surface area for the lipase to work on. This process is called emulsification.
How does bile help to digest fats in the stomach?
Bile is an alkali, therefore it neutralises the acid in the stomach. As a result, the enzymes can work more effectively (they don’t work well in acidic conditions).
How do glucose and amino acids enter the blood?
They diffuse into the plasma in the blood.
How do larger molecules, such as fatty acids, enter the blood?
They diffuse into a fluid called lymph, which travels around the body in the ‘lymphatic system’.
How is the small intestine adapted for absorbing food molecules?
It is very long, giving lots of time for absorption.
It has millions of little bumps called ‘villi’ that give it a large surface area for absorbing.
Villi are thin and permeable.
What is ultrafilitration (happens in kidneys)?
Water, urea, salts and glucose are squeezed into the bowman’s capsule at high pressures. Larger molecules, such as proteins, are too big to be squeezed into the capsule, therefore they remain in the blood.
How are sugar and salt re-absorbed in the kidney tubules?
Through active transport - i.e. the substance is transferred against the concentration gradient. It moves from where there is not much of it to where there is a lot.
How does ADH control water content?
ADH makes the kidney nephrons more permeable, meaning that more water is re-absorbed. As a result, there will be more water in our blood plasma.
Why does the water concentration need to be constant between our blood plasma and the tissues in our body?
Since the concentration is constant, the amount of osmosis happening is limited (since osmosis requires a concentration gradient). As a result, we do not lose too much water to surrounding tissues during transporation.
What effect does the FSH hormone have on a woman’s body?
It causes an egg to develop in one of the ovaries. It also stimulates the ovaries to produce oestrogen.
What effect does the Oestrogen hormone have on a woman’s body?
It causes the lining of the uterus to repair itself and then begins to stimulate the production of the LH hormone.
What effect does the LH hormone have on a woman’s body?
It stimulates the release of an egg (ovulation) around day 14 of the Menstrual Cycle. Indirectly, it stimulates the production of the progesterone hormone.
What effect does Progesterone have on a woman’s body?
It maintains the lining of the uterus and stops the production of the LH hormone.
What is the name of the mechanism that controls hormone levels involved in the Menstrual Cycle?
Negative Feedback
What is the role of synovial fluid in our joints?
It lubricates the joints, reducing friction and therefore allows them to move more easily.
Why do we have cartilage on the ends of our bones?
It stops two bones at a joint from rubbing against each other, and also acts as a shock-absorber.
How our bones at a synovial joint held together?
Through ligaments, which have a high tensile strength (won’t snap) and high elasticity.
What is the advantage of a double circulatory system over a single circulatory system?
A double circulatory system can pump blood around the body at a higher pressure - this allows us to transport vital substances such as oxygen and glucose to the body at a much faster rate.
What is the role of the SA node (sino-atrial node) within the heart?
It stimulates the atria to contract.
