Homeostasis Flashcards
What is the definition of homeostasis
The regulation of internal conditions in a cell or organism to give optimum conditions for it to function in response to internal and external changes
What is it in cells or organisms that needs optimal conditions?
Enzymes work best in their optimum conditions, most reactions inside cells and organisms involve enzymes
What exactly is controlled during homeostatis in humans?
Blood glucose concentration, body temperature and water levels
What are the automatic control systems in the body for homeostatis?
The nervous system and the endocrine hormonal system
What is three parts to all control systems have?
Receptor cells, coordination centres and effectors
What is a receptor cell?
Any cell that can detect changes in the environment. These changes are called stimuli, e.g. chemical receptor cells on the tongue
What is a coordination Centre?
An area of the body that receives and processes the information from the receptors, e.g. brain, spinal cord and pancreas
What is an effector?
Effectors cause the responses to happen so that the body is return to optimum level is e.g. muscles and glands
What is a neuron?
A nerve cell they are quite long and thin, and they can transmit information as electrical pulses
What is the CNS?
The central nervous system is it made of two parts of the brain and the spinal cord
What happens at the CNS?
The CNS receives impulses from receptors cells, and then sends impulses out to the effectors.
The effect would be a muscle contracting or a gland secreting hormones.
What is the order of the pathway of a reflex arc?
Stimuli, receptor, coordinator, effector, response
What are the three neurons in the reflex arc?
Sensory neuron
relay neuron
motor neuron
What is the role of a sensory neuron?
Sensory neurons transmit an electrical impulse from the receptor cell to the CNS
What is the role of a relay neuron?
Relay neurons are found in the CNS, usually in spinal cord, it takes the information from the sensory neuron and passes the information to the motor neuron
What is the role of a motor neuron?
Motoneurons transmit an electrical impulse from the CNS to the effector, e.g. a muscle or a gland
What is a synapse?
Synapses a tiny gaps between neurons as electrical signal Compas, across the gap. The information is converted into chemicals called neurotransmitters.
How does a neurotransmitters cross a synapse?
Neurotransmitters move across a synapse by diffusion. When they reach in the next neuron, they cause a new electrical impulse to be sent.
Why does the speed is slow down when an impulse reaches a synapse
The electrical impulses much faster than the chemical neurotransmitter, so every synapse slows the speed of the overall reaction
Why did reflexes help reduce damage by injury?
They are automatic and rapid, so don’t involve the conscious part of the brain. The response is quicker than if the impulse travel to the brain so less damage happens.
What sort of factors slowdown reaction times?
Alcohol, depressant, drugs, tiredness and dehydration can all slow down the speed of a reaction.
Stimulant drugs can speed up reactions too
What is the required practical for reaction times?
Measuring how fast am on racks by doing a computer reaction test, or by dropping a ruler and measuring how many centimetres have dropped before they catch it
What does the brain do?
The brain controls complex behaviour
It can do this because it is made of billions of interconnected neurons
What are the main areas of the brain?
Cerebral cortex
Cerebellum
Medulla
What is the cerebral cortex?
This is the outer layer of the cerebrum and is split into two hemispheres and is highly folded
What does the cerebral cortex do?
It controls intelligence, personality, conscious, thoughts and high level functions such as language and verbal memory.
What is the cerebellum?
This is an area tucked under the cerebrum.
What does the cerebellum do?
Controls balance, coordination of movement and muscular activity.
What is the medulla
A small swollen area where the spinal cord meets the brain.
It is the one of the most basic brain areas and is found in many animals
What does the medulla do?
It’s controls unconscious activities such as breathing rate and heart rate.
How do you neuroscientists identify what different regions of the brain do?
They study patients with brain damage.
They also electrically stimulate different parts of the brain during the MRI scanning to identify where the effects of the brain are seen.
Why is it so difficult to investigate and treat brain disorders?
The brain is extremely complex so it’s hard to understand.
Also it is very delicate so it’s easy to damage. It is also very difficult to examine without causing damage.
What is the eye?
I sense organ containing light receptor cells. They are sensitive to light intensity and to colour
What is the retina?
The retina is a layer inside the back of the eye where the light sensitive receptors cells are found.
What is the optic nerve?
The nerve that connects each eye to the brain
electrical signals are sent to the area of the brain that identifies what we are seeing
What is the sclera?
The tough white layer the outside of the eye. It prevents the eye from being burst by physical damage.
What is the cornea?
The front of the sclera is a clear area to allow light to pass through into the eye. The cornea is the name for this clear zone.
What is the iris?
The iris is the colours muscle inside the front of the eye that controls the size of the pupil.
This allows enough light in and prevents damage from too much light entering.
What are the ciliary muscles?
These are muscles that control the size and the shape of the lens inside the eye
when they contract the lens is rounder when they are relaxed, the lens is pulled thinner.
What are the suspensory ligaments?
These are the connecting tissues between the ciliary muscles and the lens. When they pull on the lens, it is stretched flatter.
What is accommodation?
accomodation is the changes in the shape of the lens that allows us to clearly see objects both far away and close up.
If this does not work properly you need spectacles.
What happens when we focus on a distant object?
Ciliary muscles relax on the suspensory ligaments are pulled tight. The lens is pulled thin, and light rays are only slightly refracted.
What happens when we focus a near object?
Ciliary muscles contract on the suspensory ligaments loosen. The lens is a thicker and light rays are refracted strongly.
What is the usual treatment for long sightedness hyperopia?
Long sighted people can see far away objects clearly, but not close-up ones. They need convex lenses to refract the light rays, more so they focus more on the retina when reading.
What is the usual treatment for short sightedness myopia?
Short sighted people can see close objects clearly not far away ones.
They need a CONCAVE lenses which reduce the effect of the lens refracting the light ray so they focus on the retina.
What are the new technologies that can be used to treat vision defects?
Hard and soft contact lenses, laser surgery to reduce the cave of the cornea and replacing the lenses in the eye if necessary.
Which part of the brain controls body temperature?
A region called the thermoregulatory centre which is in the hypothalamus just above the medulla.
If the skin temperature receptors detect a change, what happens?
Skin temperature receptors send impulses to the thermoregulatory centre, so that a response to be coordinated.
Where are the temperature receptor cells in the body?
In the skin, detecting changes in the blood temperature of the surface and also in the thermorgulayory center, detecting changes in the blood temperature in the brain.
How to sweating help us to transfer more heat energy to our surroundings
It takes a lot of energy to evaporate water, so when we put sweat into our skin (made in the sweat glands), it transfers our body heat when the water evaporates. we get cooler.