Biology yr 8 Flashcards
capillary
a fine branching blood vessel that form a network between the arteries and veins
villi
any of the small, finger-like membrane on your small intestine
used to increase surface area
carbohyderate
an organic compound such as sugar or starch, and is used to store energy
cereals, bread, pasta, rice and potatoes
lipid
fatty compounds that perform a variety of functions in your body such as storing energy, sending signals through the body, making hormones and more
e.g.cholestrol
butter, oil and nuts
protein
large, complex molecules that play many critical roles in the body
e.g. keratin. fish, meat, eggs, pulses, beans, dairy
are used for growth repair, making enzymes, making insulin and more
fibre
any elongated, thread-like structure
vegetables, bran (cereal)
undigestible - provides bulk to food so it is easier to push food along by peristalsis
vitamin
a group of substances that are needed for normal cell function, growth, and development
fruit, vegetables, dairy foods
to be consumed in small quantities
leptin
the hormone that regulates hunger by providing the sensation of satiety (feeling full).
does this to help body maintain a normal weight long-term
the organ in which digestion by enzyme is
completed.
small intestine
2 parts of the digestive system where physical and chemical digestion take place
mouth and stomach
two ways the small intestine is adapted to its function
- Thin wall - to speed up diffusion / absorption
- Rich blood supply - carry away absorbed food molecules
- Covered in villi - increases surface area
why food needs to be digested
- Large food molecules are broken into small molecules
- These can be reabsorbed through the wall of the small intestine
- transported in blood to where needed in the body
When food hits your stomach, what is the sensation that contributes to a feeling of fullness
stretching
What parts of your body are important for sensing the fullness of your stomach?
- the vagus nerve
the brain stem
the hypothalamus
hormone released when nutrients and gastrointestinal hormones (hormones that the intestines make) are present in the blood
insulin
what cells make leptin?
fat cells
why is it that eating more slowly helps you feel fuller?
It gives your body time to release and respond to hormones.
peristalsis
- muscle contractions
- It keeps food moving
first food group to be digested
carbohyderates
digestive enzyme is found in the mouth
salivary amylase
why do enzymes need to be at a certain ph level
Each enzyme has an optimum pH range. Changing the pH outside of this range will slow enzyme activity and/or cause it to denature
role of bile in digestion
- breaks down fats into fatty acids, which can be taken into the body by the digestive tract.
- neutralises stomach acids to regulate Ph levels in the small intestine
calorie
a unit of energy that is the amount of energy needed to heat one gram of water by one degree celsius
joule
Joule = (mass of water (g) x 4.2 x
temperature difference (°C)) / mass
of food (g)
state the role of bacteria in the digestive system
They can
- digest certain substances humans cannot digest
- reduce chance of harmful bacteria multiplying, causing disease
- produce vitamins that humans need e.g. vitamins B & K
obesity definition
when the energy input (food you consume) is higher than the output (exercise, physical movement)
gall bladder
it stores bile and secretes it into the small intestine
Vitamin A function
important for good vision
Vitamin C function
the formation of connective tissues (e.g. gums)
Vitamin B
the formation of red blood cells
Vitamin D
the formation of teeth and bones
Vitamin K
helps your blood to clot, if you cut yourself
undernutrition
when the energy input (food you consume) is lower than the output (exercise, physical movement)
