Responces To A Changing Environment Flashcards
What is keeping the internal environment of a body stable called
Homeostasis
What is water in the body used for
Allowing substances to dissolve and for chemical reactions. Too much water leads to high blood pressure and swelling
What is our body temperature
37 celcious
What is a gland
Something stat produces a substance then releases it
How and what is the control of water called
Osmoregulation is the control of water in the body and is controlled by the kidney. Too much water, more urine, too little, less urine and brain is triggered to make you feel thirsty
What is thermoregulation
The controlling of the temperature of the body
How is cold temperature controlled
The body uses hypothalamus in the brain which constantly monitors the temperature of the body and uses nerve endings in dermis’s on the skin to check the external temperature. If the external temperature is too cold and reduces the internal temperature, the hypothalamus causes muscles to shiver to produce heat and causes hair erector muscles to make hair stand up to trap air and reduces blood flow at the surface of the skin to reduce heat loss
How is hot temperature controlled.
The hypothalamus detects the body going over 37 and causes sweat glands to produce sweat to cool the body down and increases blood flow at the surface of the skin to release heat into the environment
What thermoregulation called in terms of feedback
Negative feedback: as temperature goes up body cools down and vice versa
What is vasoconstriction and vasodilation
Construction of capillary’s on surface of skin to reduce blood flow and heat loss.
The increasing of blood flow in capillary’s to lose heat to the external environment.
What is a stimulus
Anything body is sensitive too
What kind of cells detect a stimulus
Receptor cells
What do receptor cells detect
Electric impulses which are then sent to the brain
What happens in a neurone
Receptor cells detect impulse which goes to the dendrites which pass the impulse to the dendrons which carry it towards the cell body. The impulse goes past the cell body and through the axons. Axon endings then pass on the impulse to other neurones.
What is a nerve
A bundle of neurones
What is the spinal cord
A cord that connects to the brain and is packed with nerves
What is the central nervous system
The spinal cord and brain make the central nervous system and it controls the body
Why are effectors
Parts of the body that respond to impulses from receptor cells including muscles and glands
What are the neurones that take impulses to effectors
Motor neurones and have no dendrons, the dendrites are on the cell body
What are relay neurones
The neurones that make up the brain and link motor neurones to sensory neurones in the spinal cord
What is the fatty layer that surrounds axons
A fatty layer called the myelin sheath
What is the myelin sheath for
To insulate the neurone from others and allows impulses to be carried faster
What happens in a motor neurone
Dendrites on the cell body collect the impulse from other neurones and the impulse travels axon and to the axon ending which passes the impulse to effector cells
What is p a synapse
The gap between the part of 2 neurones that connect. Impulses are passed through the synapse by chemical substances called neurotransmitters
Good and bad of a synapse
Good: only axon endings can produce neurotransmitters meaning the impulse can only travel in one direction
Bad: slow down the impulse slightly
What are reflexes
Automatic actions done by the body to protect it. E.g. Dropping a hot object to stop the body burning
How do reflexes happen
Instead of the impulse going to the brain then back to the effector cells, it goes from the sensory neurone directly to a motor neurone to the effector cell. These pathways are called reflex arcs. These bypass the part of the brain involved with conscious thought .
Why are reflexes so fast
They only contain 2 neurone, sensory and motor and some have internet to e that connect sensory to motor
Where are hormones made
In endocrine glands
What are and what do hormones do
They are chemical messengers that travel in blood and their presence causes certain parts of the body to respond to them. E.g release of testosterone in testes to a cause puberty.
5 hormones and what they do
Adrenaline from adrenal glands, speeds heart beat
Insulin from pancreas, lowers blood glucose levels
Oestrogen from ovaries, causes production of female reproductive organs
Testosterone from testes, causes production to male reproductive organs
Glucagon from pancreas do, increases blood glucose levels
How are glucose levels controlled
Too much, insulin from pancreas is released causing the glucose in blood passing through liver to be converted into glycogen which stores glucose for when it’s needed
Too little, glucagon produced by pancreas and tells liv to convert glycogen into glucose
(If their is glucaGON the it means the body wants glycogen GONE and turned into glucose)
What is and how is BMI calculated
An estimate on how healthy someone is. Anything over 30 is classed as obese
Weight in KG divided by (height in M squared)
What is type 1 diabetes
When the pancreas doesn’t produce insulin and needs to be injected after meals to control glucose levels
What happens if glucose levels are too high.
Tiredness and potential damage to organs such as eyes and insulin released
What happens if glucose levels are too low
May fall unconscious and glucagon released
What causes type 2 diabetes
High fat diets and not much exercise.
What is diabetes
A disease in which the body can’t control glucose levels because insulin isn’t produced or the cells become resistant to it
What is tropism
A plants response to growing towards or away from light
What is a tropism that responds to light called
Phototropism. Plant roots are negatively phototropic
Plant shoots are positively phototrophic
What causes positive phototropism
Auxins in plant shoots to the side facing away from light and cause the cells in that part of the shoot to elongate which bends the shoot towards the light.
Where are auxins produced and what happens if that part of the shoot is missing (phototropism)
Auxins are produced in the tip of a shoot and without the tip the plant would just grow upwards
Where are auxins produced and what happens if that part of the root is missing (gravitropism)
Produced in root tips and are pulled down by gravity, this stops elongation of the bottom cells and causes the root to bend down.
What happens after the period of darkness and cold a plant needs ends
The seed releases hormones called gibberellins that cause the starch in the seed to become sugars that the seed needs to grow. Gibberellins also stimulate flower and fruit production
What is a selective weed killer
A hormone that only effects certain plants and causes them to grow out of control and die
What is artificial auxin used for
Used by farmers to kill weeds as it only targets plants with broad leaves such as dandelions and causes them to grow out of control and die but doesn’t affect farmers crowds such as wheat as the don’t have broad leaves
How can plants be cloned
Cuttings can be taken and the bottom of the cutting dipped into synthetic auxins called root power causing them to grow roots and become a new plant. It’s quicker than using seeds
How are seedless fruits made
The flowers of the fruit are sprayed with artificial hormones that make them produce the fruit but not the seed.
How can ripening be controlled
Hormones can be sprayed to stop fruit ripening and falling of or natural hormone gases (ethene and ethylene) can be used to make fruit ripen at the same time so they can all be picked at the same time
