B1.2 Flashcards
Why does water content in the body need to be controled
Too little chemical reactions in cells won’t be able to take place and substances won’t be able to dissolve into the blood
Too much can cause swelling and high blood pressure
Why does temperature need to be controlled in the body
Needs to be kept at the optimum temperature for enzymes to increase rate of reactions in the body
What is the process of keeping the internal environment stable called
Homeostasis
What is a gland
A part of the body that creates a substance and then releases it
What is the control of water in the body called
Osmoregulation
How do we lose water
Through sweat and our breath
How is water regulated in the body
Too much and the kidneys produce lower conçentration urine, has more water in it
Too little kidneys produce higher concentration of urine with less water and tells the brain to make you thirsty
What is the control of the temperature of our body called
Thermoregulation
What is our ideal temp
37C
What is the hypothalamus and what does it do
Small part of the brain that measures external temperature through the info it receives from nerve endings in the dermis part of the skin. It also measures internal temperature of the body through the temp of the blood
What is the dermis part of the skin
The layer of skin beneath the epidermis (outer most layer) and contains nerves endings, blood vessels and hair roots
How is temperature controlled in our body if too cold
If too cold, hypothalamus causes muscles to shiver which releases energy and heat. Erector mussels in the dermis contract to make hairs stand up, this helps other mammals keep warm as it traps the warm air, however it doesn’t help us much
Vasoconstriction occurs in the blood vessels near the skin
If too hot
Sweating occurs and when the sweat evaporates, some of the heat is transferred from the skin to the surroundings.
Vasodilation occurs on capillaries in the dermis
What is vasodilation and vasoconstriction
Vasodilation is where the capillaries near the surface of the skin widen to increase blood flow so heat is transferred onto the skin from the blood and sweat removes that heat.
Vasoconstriction is where the capillaries near the surface of the skin constrict to reduce blood flow and reduce blood loss
How is thermoregulation an example of negative feedback
If too hot, body tries to reduce temp, if too cold, body tries to heat up.
What are sense organs and what do they all contain
Organs that detect changes inside and outside the body and they all contain receptor çells that detect a stimulus
How does the brain know about changes
Receptor cells detect the stimulus. They then create elctrical signals called impulses and they are sent to the brain which then sends impulses to other parts of the body to make something happen
What do impulses travel along and what is this process called
Travel along neutrons and this is called neurotransmission
What is the structure of a sensory neurone and how does it work
Dendrites on the end of dendrons detect impulses from receptor cells. The impulses travels along the dendrons and into the cell body, from there it travels through the axons and into the axon endings. Axon endings then pass on the signal to others dendrites
What is a nerve
A bunch of neutrons packed together
What is the CNS and what is it made of
Central nervous system and is made of the brain and spinal chord. The cns controls your body
What happens when the brain receives and impulse
The brain coordinates a response. In a response, impulses are sent to effectors and they carry out an action. Effectors include muscles and glands
What is the structure of a motor neurone and what are they for
They take impulses to effector cells. They are like sensory neurones but have no dendrons and the dendrites are attached to the cell body
What are relay neurones and what do they do
They are short neurones that take signals from sensory neurones to motor neurones. They make up the brain and spinal chord
What is the myelin sheath and what is it for
It’s a fatty layer of neurones and goes over the axons. It insulates and protects the axon from other neurones and allows impulses to be carried faster
What is a synapse and why are they useful and not useful
They are the gap between an axon ending and dendrites, they are about 0.00002cm wide. They are good as only axon endings can make the chemical that the dendrites Receive (neurotransmitter) which means the signal will only travel in one direction. There are bad because they slows down the impusle
What is a reflex
An automatic response to a stimulus that needs no conscience thought, it bypasses relay neurones
What is a reflex arch
A neurone pathway in which the sensory neurone directly controls the motor neurone so neither the brain or spinal chord every receive the impulse, making it faster. Some reflex archs have an interneurone that connects the sensory neurone to the motor neurone
Name 3 reflexes
Stop touching something hot, pupils changing size based on light, blinking when something comes to your face
Where are hormones made and released
From glands called endocrine glands
What are hormones
Chemical messengers that travel in the blood, causing certain parts of the body to respond in a certain way due to their presense
What hormone controls urine concentration
Anti diuretic and is released from the pituitary gland near the brain
What is adrenaline and where is it from
A hormone released from the adrenal glands and increases heart rate
Insulin
Made by the pancreas and lowers blood glucose levels
Oestrogen
Made by ovaries and causes development of female reproductive system during puberty
Glucagon
Produced by pancreas and raises blood glucose levels
Testosterone
Made by the testes and causes development of male reproductive organs in puberty
How are glucose levels controlled
When too much glucose is detected, pancreas releases insulin, this travels to the liver and causes it to convert glucose into glycogen. This means less glucose in blood
Too little glucose, glucagon is released by the pancreas which tells the liver to convert they glycogen into glucose, raising the levels
What does diabetes cause and why is it bad
Someone with diabetes can’t properly control their glucose levels which is bad as too little can cause un consciousness and too much can damage organs such as eyes
What is type 1 diabetes
The pancreas doesn’t make insulin at all so it has to be injected. It is injected into the fatty layer beneath the ski. (Subcutaneous fat layer) because fat quickly absorbs insulin so it spreads through the body fast
What is type 2 diabtetes
Diabetes that usually occurs when the person doesn’t exercise enough or eats too much sugar or is obese. It is when the persons cells don’t respond to insulin because they have become resistant, even though the insulin is there. Can be controlled by changing diet and doing more exercise
How is BMI calculated
Weight in KG/height in M^2
What is phototropism
A type of tropism in which causes the plant to either grow away or towards a light stimulus
What are auxins and what do they do in phototropism
They case plants to grow towards the light and are hormones.
When light hits a side of a plant, the auxins move to the shaded part. There presence causes those cells to elongate, in turn bending the shoot towards the light
What is gravitropism
Response to gravity in plants
What do auxins do in gravitropism
They are found in root tips and have the opposite effect to when they are in shoots, in roots, they cause the cells to stop elongating. They are attracted towards gravity when in roots, this means the cells around them stop growing and the others continue to elongate and bend the root down
What are gibberlins and what do they do
They are another plant hormone and is released once the period of darkness before a seed can terminate is over. They cause the starch in the seed to become sugars and create the energy needed to grow. They also stimulate flower and fruit production i some species
What is a selective weed killer
A weed killer that only kills certain types of plant
How does auxin weed killer work and why is it good for farmers
It only causes plants with broad leaves such as daisies and dandelions to grow out of control and die, leaving the narrow leaf plants such as wheat unharmed
How can plants be cloned
A cutting can be removed and have all but one leaf removed, the bottom of the cutting is then dipped into synthetic auxin powder which causes rapid growth of roots and the cutting can then be planted. This is much faster than growing the plant from a seed
How can seedless fruit be made
The flowers of the plant are sprayed with hormones which causes the fruit to grow without seeds
How are gibberlins used with seedless grapes
Some species of grape are naturally seedless but make small fruit. Gibberllins can be sprayed onto these and cause them to grow larger
How can fruit be ripened and why is this good
Ethene is seed to ripen some fruit. This means it can be picked un ripe and ripened once they are ready to be sold in supermarkets
