Biology Homestatis Flashcards
What do enzymes and cells require?
What is homesostasis ?
When does it have to stay stable ?
Enzymes and cells require stable conditions in order to work
Process by which you keep internal conditions constant to maintain optimum conditions for the reaction
Has to stay stable even when the external and internal environment changes
What is meant by internal conditions ?
What does homeostasis consist of?
Examples of automatic control systems?
the conditions within the body, including temperature, blood pressure, blood sugar level
homeostasis consists of automatic control systems
Nervous system and hormonal
Three Features of an automatic control system ?
What is negative feedback ?
Three features -receptor cells,coordination centre ,effector
negative feedback -When the level of something gets too high ot to low ,negative feedback brings it back to normal .
Explain how automatic control system work ?
What is meant by the environment ?
Give an example of internal or external condition
Firstly the receptor cell detects a stimulus (change in the environment)
Receptor passes information to coordination center such as (brain ,spinal cord or pancrease)
coordination center -recieves and processes information passing this on to effector
effector-muscle /gland job is to carry out response
What happens if receptor detects stimulus is too high ?
What happens if receptor detects stimuls is too low ?
What do all automatic control systems have ?
Effector produces a response that counteracts the change, restoring optimum conditions /levels
Stimulus, receptor, coordination center, effector,response
Nervous system ,What is it connected to body by ?
sensory neurones
Relay neurones
motor neurones
consists of two parts ;CNS-central nervous system (brain and spinal cord)connected to the body by sensory and motor neurones
The peripheral nervous sytem -all over nerves that send electrical impulses to CNS and back out again .
sensory neurones-neurones that carry electrical impulses from receptors to CNS
Relay neurones-CNS to CNS
Motor neurones -carry electrical impulses from CNS to effectors
What is a synapse?
Nerve signal is transferred by ?
the connection between two neurons
nerve signal is temporarily transformed into chemicals that diffuse across the gap
Chemicals set off a new electrical signal in next neurone
Reflex arc
Why is it necessary ?
They are rapid ,automatic,don’t involve conscience part of the brain .
The pressure of pin is a stimulus which is detected by receptor cells .
Stimulate a sensory neurone carrying an impulse from finger to spinal cord .
Spinal cord will transfer it to impulse to relay neurone .
rely neurone then passes it to motor neurone which passes back to to effector
Investigation reaction time
Can be affected by age,gender,drugs
Caffeine is a drug that can speed up a persons reaction time
1)person should keep their arm resting on the edge of a table
2)Hold a ruler vertically between thumb and forefinger ,make sure the zero end of a ruler is level with thumb and finger .
3)Let go without any warning ,repeat test several time to measure the mean distance ruler fell .
4)The person should have a caffeinated drink .after 10 mins repeat
control variable -same person ,should be dropped from same height ,person should use same hand ,
Reaction time using a computer
why would you use computer?
what can it record in ?
what does it remove?
computer test .
Person being tested clicks the mouse as soon as they see a stimulus on screen
-computers are more precise ,remove human error
-can record miliseconds
-removes ability to anticipate the drop
The brain
What is it part of ?
What is it in Charge of ?
Part of CNS including spinal cord
billions of interconnected neurons
In charge of all complex behavoir
What does cerebral cortex do ?
What does cerebellum do ?
What does Hypothalamus do?
What does the Medulla do ?
Cerebral cortex -(wrinkly bit )Responsible for consciousness,intelligence,memory and language
Cereberal split into two halfs (hemispheres)
Left hemisphere controls the muscles on the right side and the right hemispheres controls the muscles on left side .
Cerebellum-responsible for muscle coordination,balance
Hypothalumus-regulating body temp and sends signals to pituitary glands .
Medulla -controls unconscious activities
How scientist study the brain
Three ways ?
first way ?
second way ?
third way ?
1)Study patients with brain damage -if a small part of the brain has been damaged, effect it has on the patient can tell you about what the damaged part of the brain does.
2)Electrically stimulated different parts of the brain -push tiny electrode into tissue ,by observing what stimulating different parts of the brain does its possible to get an idea of what those parts do .
3) MRI produces a detailed picture of the brains struc
ures.Use this to see what parts of the brains are active when people are doing things (uses magnetic fields)
Why treating the brain can be so difficult ?
Three reasons ?
Wide range of things that can go wrong.
Its encased within our skull and tissue surrounding is fragile so the brain is very delicate .
Also very complex-dont know underlyimg issue
The eye
What is the sclera?
what is the cornea ?
what is the iris ?
What is the lens?
What does the retina contain ?
What is the optic nerve?
what controls the shape of the lens ?
eye -sense organ
sclera-tough supporting wall
Cornea-transparent outer layer ,refracts light into the eye
Iris-(coloured bit )contains muscles that allow it to control the diameter of the pupil and therefore how much light enters the eye depending on the distance of what you are looking at
Lens-focuses light onto the retina
Retina (contains receptor cells that are sensitive to light intensity and colour )
Optic nerve - carries impulses from receptors on retina to the brain
Ciliary muscles and Suspensory ligaments -control the shape of the lens
pupil -space in the centre of the iris wjere light passes through
