Homeostatis and Response (Paper 2) Flashcards
What is meant by homeostasis
Regulation of internal environment within cell/ organism to maintain optimum conditions for function (life)
What 3 main conditions must be controlled in homeostatis
Body temperature
Water levels
Blood glucose concentration
What 2 systems are used to control homeostasis
Nervous system
Endocrine system
3 main parts of control system
Receptor (detect change)
Coordination centre (interprets change and decides what needs to be done)
Effector (carry out change)
Part of control system that detects change
Receptor
Part of control system that interprets change/ decides what to do about the change
Coordination centre
Part of control system that carries out the change
Effector
2 types of effectors
Muscles/ glands
Negative feedback control system meaning and example of how it works
Where the automatic control system counteracts the change identified by receptors
E.g if temperature increases, it decreases the internal body temperature to keep it stable
E.g if you walk into a cold room, the receptors in our skin detect the low temperature, nervous system sends impulses to coordination centres which interpret the information, then signals are sent to the effectors e.g muscles which can shiver to overtime increase body temperature (skeletal muscles move and generate heat)
What is meant by Thermoregulation
Control of internal body temperature
Name for control of internal body temperature
Thermoregulation
Where are most receptors found in the body
Sense organs
E.g eye, skin, ear, nose wire etc
Name for process where muscles contract automatically to keep us warm
Shivering
What type of cell in the nervous system detects a change in the environment
Receptor
When body temperature is too… the blood vessels dilate
High
When body temperature is too…the blood vessels constrict
Low
What do blood vessels do when the body temperature is too high
Dilate
What do blood vessels do when body temperature is too low
Constrict
Dilate meaning
Become wider/ more open
Constrict meaning
Narrow/ restrict
Vasodilation meaning
When blood vessels dilate (open wider)
What causes vasodilation to occur
When body temperature is too high
What causes vasoconstriction to occur
When body temperature is too low
What centre in the brain controls and moniters body temperature
Thermoregulatory centre
Where in the body is the thermoregulatory centre located
Brain
What are the receptors found in the thermoregulatory centre sensitive to
Blood temperature
Main reason why our body temperature must be regulated to 37 degrees Celsius
Optimum temperature for enzymes to function
(below this temperature= lower rate of reaction)
(Above this temperature enzymes denature= lower rate of reaction then no reaction at all)
Which part of the brain is the thermoregulatory centre found in
Hypothalamus
Why does constricting blood vessels (vasoconstriction) help increase body temperature
Blood vessels that that lie near surface of skin are constricted (narrowed)
Less blood flows near surface
Less heat energy lost to surroundings
4 things body does in response to a decrease in body temperature
-Blood vessels constrict (less heat energy lost to surroundings)
-Shivering (skeletal muscles automatically contract so more respiration is required which releases more energy as heat)
-Hairs on skin stand up (due to hair erector muscles contracting- more air is trapped so provides insulation and less heat is lost from skin)
-Sweat less
Do the erector muscles contract when there is an increase or decrease in body temperature
Decrease
(Makes hairs on skin stand up to insulate body as traps layer of air preventing heat loss to warm body back up and regulate body temperature)
What happens to the hairs on the skin when the erector muscles contract and relax
Contract- hairs stand up so traps heat (insulation)
Relax- hairs lie flat to prevent insulation and cool body down
How does blood vessel dilation help cool down body in response to increase in body temperature
More heat energy can be transferred to surroundings as lots of warm blood is passing close to skin surface
What 2 things does sweat consist of
Water and salt
How does sweat help cool us down
It is a mixture of water and salts released onto the surface of the skin
As it evaporates, it takes heat energy from our body away with it (as lots of energy is required to evaporate water)
Why does blood vessels dilating help decrease body temperature
More warm blood can pass through so more heat is lost through skin to surroundings
Function of nervous system
Enables humans to react to their surroundings and to coordinate their behaviour (includes both voluntary and involuntary actions)
True or false, the nervous system includes both voluntary and involuntary actions
True
2 parts of the central nervous system
Brain and spinal cord
What type of actions don’t involve the conscious part of the brain
Reflex actions
What is a synapse
Gap between 2 neurones
(Allows impulses to cross)
Another word for short sightedness
Myopia
Another word for long sightedness
Hyperopia
Which out of myopia and hyperopia means short sightedness
Myopia
(Think myopia is the shorter word)
3 types of neuron
Sensory
Relay
Motor
The brain is the… centre of the body
Control
What part of the body is the control centre of the body
Brain
Name for bony case surrounding the brain
Skull
What is the skull
Bony case that surrounds the brain
Below the brain are membranes called….
Meninges
What are meninges
Membranes below the skull that protect the brain
Name for outer crinkly layer of brain important for consciousness, intelligence, language and memory
Cerebral cortex
What 4 things is the cerebral cortex important for
Memory
Language
Intelligence
Consciousness
What is at the back of the brain and important for muscular activity and balance
Cerebellum
Role of cerebellum at back of brain
Muscular activity and balance
What part of the brain is the regulatory centre (including containing the Thermoregulatory centre)
Hypothalamus
What is at the base of the brain and important for involuntary actions like heart rate, gut movements and breathing
Medulla
Where about in the brain is the medulla
Base of brain
Role of medulla at base of brain
Involuntary activities (heart rate, gut movements, breathing…)
Part of brain responsible for involuntary actions like breathing
Medulla
(Found at base of brain)
What gland in the brain controls hormones
Pituitary gland
Role of pituitary gland in brain
Controls hormones
Definition of receptor
Groups of specialised cells that enable us to detect changes in the environment
Neuron definition
Specialised cells that conduct electrical impulses through the body
Nerve definition
Bundle of many nerve fibres (neurons) enclosed within a protective sheath
What does a sensory neuron connect
Receptor to coordination centre
The sensory neuron connects the… to the…
Receptor, Coordination centre
Type of neuron that connects receptor to coordination centre
Sensory
What does a motor neuron connect
Coordination centre to effector
The motor neuron connects the… to the…
Coordination centre, Effector
What does the relay neuron do
Create shortcut between sensory and motor neurons for our reflexes
Which type of neuron creates a shortcut between the sensory and motor neurons
Relay
Events in a reflex action
Receptor detects stimulus
Sensory neuron sends electrical impulses to relay neuron
Relay neuron connects sensory neuron to motor neuron
Motor neuron sends electrical impulses to effector
(Motor neurone takes away need to go past brain (coordination centre) I think
What is a reflex action
Rapid and automatic response of the nervous system that doesn’t involve conscious thought
(Doesn’t require brain)
Name for nerve pathway followed by a reflex action
Reflex arc
What is a reflex arc
Nerve pathway taken in a reflex action
Main purpose of reflex actions
Prevent injury (keep you out of danger)
What does CNS stand for
Central nervous system
What does the central nervous system (CNS) consist of
Brain and spinal cord
True or false, neuron and neurone are the same thing
True!
How do the brain and spinal cord receive information about what’s happening in the rest of the body
Sensory neurones
(Sensory neurones go from receptor to brain/ spinal cord)
How does the CNS send impulses back out to the body (once it’s decided what to do with the information given to it by the sensory neurones)
Vía motor neurones
Name for cells found in nerves that carry information
Neurones
What coordinates the response to a stimulus
The brain
Three types of neurones that are part of the central nervous system
Relay
Motor
Sensory
True or false, each of the brain’s regions performs a different function
True
When light hits the eye what’s the first structure that it meets
Cornea
Why is the cornea transparent
Allows all light that hits it to completely pass through (the cornea is the first part of the eye that light hits)
True or false, the cornea has blood vessels
False
It has no blood vessels so that it is transparent and light can completely pass through (it’s the first part of the eye that light hits)
Why is the cornea transparent with no blood vessels
So that light can completely pass through (it’s the first part of the eye that light hits)
What does the cornea do to all the light that passes through it
Causes it to refract
The cornea causes all the light that passes through it to…
Refract
Part of eye that causes all light that passes through it to refract
Cornea
Role of cornea
Allows all light that passes through it to refract
Refraction meaning
When something changes direction when it meets a new medium (material)
(E.g light changes direction when it passes through the cornea of the eye)
Name for coloured part of eye
Iris
The iris controls how… the pupil is
Big or small
What part of the eye controls how big or small the pupil is
Iris
True or false, the pupil isn’t an actual structure of the eye
True
It’s a gap in the middle of the iris that allows light to pass through to the lens
Name for gap in middle of iris that allows light to pass through to lens
Pupil
True or false, both the role of the lens and cornea refract light
True
2 parts of eye that refract light
Cornea and lens
Both the cornea and lens refract light but which can change shape (gets thicker/ thinner)
Lens
Purpose of lens being able to change shape
Allows it to control how strongly it refracts the light to help focus near/ distant objects
What about the lens makes it able to control how strongly it refracts the light
It can change shape
The lens allows light to always focus on the…
Retina
Why is it good if the lens can change how strongly it refracts light (by changing shape)
Allows light to always focus on retina in order to focus both distant and nearby objects
How many different types of receptor cells is the retina made up of
2