Chapter 12 - Coordination And Response Flashcards
What does the endocrine system consist of?
Hormones and glands
What does the nervous system consist of?
Nerves and brain
Name the 2 parts that the nervous system is divided into:
Central nervous system
Peripheral nervous system
What does the central nervous system consist of?
1) Brain
2) Spinal cord
What does the peripheral nervous system include?
All the nerves that connect the rest of the body to the central nervous system
What is the difference between a neurone and nerve?
A single nerve cell is called a neurone. Neurones are Clustered together to form a large nerve fibre.
Name 4 components that make coordination possible:
1) sense organs
2) sensory impulses
3) motor impulses
4) effectors
What are the 3 classifications of neurones?
1) sensory neurones
2) relay neurones
3) motor neurones
Where are sensory neurones found?
Connected to sense organs
Where are relay neurones found?
Found in CNS
Where are motor neurones found?
Connected to the effectors
What is another name for motor neurones?
Effector neurones
What do sensory neurones do?
They carry messages from a sense organ to the CNS.
What do relay neurones do?
Connect neurones to one another.
What do motor neurones do?
They transmit messages from the CNS to the effectors.
Name the 3 basic structures of a neurone:
1) cell body - contains the nucleus and a little cytoplasm
2) dendrites - branching fibres that extend from the cell body
3) nerve fibre(s) - filaments) of cytoplasm that is surrounded by an electrical insulating sheath. These fibres extend out of the main cell body and transmit electrical impulses.
Define stimuli:
Changes in the environment that can be detected by organisms.
Define receptors:
Cells/groups of cells that detect stimuli.
Define effectors:
Parts of the body that respond to a stimulus
Eg. Muscles and Glands
Define coordination:
Ensuring that the actions of different parts of the body work together.
Define nerve:
A group of neurone axons lying together
(Like an electrical cable containing many wires)
Define a neurone:
A cell that is specialised for conducting electrical impulses rapidly.
Define a motor neurone:
A neurone that transmits electrical impulses from the CNS to an effector.
Define axon:
A long, thin fibre of cytoplasm that extends from the cell body of a neurone.
Define dendrites:
Short fibres of cytoplasm in a neurone.
Define nerve impulses:
An electrical signal that passes rapidly along an axon.
What are the 2 methods that receptorsuse to send information to the effectors?
1) Nerves (nervous system) - fastest way
2) Hormones (endocrine system) - slower way
What are the cells that make up the nervous system?
Neurones
What is the structure of a neurone that enables it to transmit electrical signals very quickly?
Long, thin fibres of cytoplasm stretching out from the cell body.
(Shorter ones - dendrites)
(Longer ones - axons)
Briefly explain how electrical impulses move through a motor neurone?
1) The dendrites pick up electrical signals from nearby neurones
2) The signal passes to the cell body
3) The nerve impulses then pass along the axon (which might pass it to another neurone)
What myelin?
A layer of fat and protein around some of the nerve fibres in mammals.
What is the function of myelin?
It insulates the nerve fibres → there are narrow gaps in the myelin sheath → carry impulses a lot faster
Eg. In a cat, a myelinated nerve fibre carries impulses at up to 100m per second.
Whereas without myelin, it can only carry impulses at about 5m per second.
What is the role of the CNS?
To coordinate the electrical impulses traveling through the nervous system.
What is the CNS made up of?
Neurones
What is the PNS made up of?
1) Made up of nerves that spread out of the CNS
The nerves are made up of 100s of neurones.
2) Also includes the receptors in our sense organs.
What happens when a receptor detects a stimulus?
The receptor sends an electrical impulse along a neurone to the brain/spinal cord.
The brain/spinal cord then receives the impulse and sends it on along the **appropriate nerve fibres* to the appropriate effector.
What is a reflex arc?
A series of neurones (sensory, relay and motor) that transmit electrical impulses from a receptor to an effector.
What is a reflex action?
A means of automatically and rapidly integrating and coordinating stimuli with the responses of effectors.
Define Central Nervous System:
The brain and spinal cord.
Define Peripheral Nervous System:
The nerves outside the brain and spinal cord.
Define sensory neurone:
A neurone that transmits electrical impulses from a receptor to the CNS.
Define relay neurone:
A neurone that transmits electrical impulses within the CNS.
Why are reflex actions useful:
You don’t waste time thinking what to do. Reflex actions are automatic.
What happens when you receive more than one stimulus at once?
These stimuli will be combined to produce electrical impulses in sensory neurones.
These will travel fast around the reflex arc and produce an appropriate and fast response.
Define a synapse:
A junction between two neurones.
Define synaptic gap:
A tiny gap between 2 neurones, at a synapse.
Define vesicle:
Very small vacuole.
Define neurotransmitter:
A chemical stored in vesicles at the end of neurones, which can be released to diffuse across the synaptic gap and set up an electrical impulse in the next neurone.
Define receptor proteins:
Proteins on the membrane of the second neurone at a synapse, which have a complementary shape to the molecules of neurotransmitter.
What is part of the synapse?
1) The ends of the 2 neurones on either side of the synaptic gap
2) The synaptic gap itself
How does the neurotransmitter move across the synaptic gap?
By diffusion
Why do the molecules of neurotransmitter attach to receptor proteins?
Because the shape of the neurotransmitter is complementary to the shape of the receptor proteins.
What is the function of synapses?
They ensure that nerve impulses only travel in one direction.
Define sense organ:
A group of receptor cells that are able to respond to a specific stimulus.
Define retina:
A tissue at the back of the eye that contains receptor cells that respond to light.
Define optic nerve:
The nerve that carries electrical impulses from the retina to the brain.
Define blind spot:
The part of the retina where the optic nerve leaves, and where there are no receptor cells.
Define fovea:
The part of the retina where cone cells are very tightly packed.
This is where light is focussed when you look directly at an object.
Define cones:
Receptor cells in the retina that are sensitive to light of different colours but only function in bright light.
Define rods:
Receptor cells in the retina that respond to dim light, but do not detect colour.
Define iris:
The coloured part of the eye
Contains muscles that can alter the size of the pupil
Define pupil:
A circular gap in the middle of the iris, through which light can pass.
Define iris reflex (pupil reflex):
An automatic response to a change in light intensity
The receptors → in the retina
The effector → the muscles in the iris
Define antagonistic muscles:
A pair of muscles whose contraction has opposite effects
When one contracts → other relaxes
Define refraction:
Bending light rays
Define cornea:
A transparent layer near the front of the eye, which refracts light rays entering the eye.
Define lens:
A transparent structure in the eye, which changes shape to focus light rays onto the retina.
Define accommodation:
Changing the shape of the lens to focus on objects at different distances from the eye.
Define suspensory ligaments:
Strong, inelastic fibres that hold the lens in position
When under tension, they pull the lens into a thinner shape
Define ciliary muscle:
A circle of muscle surrounding the lens,and joined to it by the suspensory ligaments
When it contracts, it slackens the ligaments so that the lens becomes fatter
What is the function of the bony socket in your skull?
Holds and protects the eye
What is the function of the liquid filling the eye?
Helps keep it in shape
What is the conjunctiva?
A thin, transparent membrane that covers the front of the eye
What is the function of the conjunctiva?
Helps protect the parts behind it
What is conjunctivitis?
When the membrane (conjunctiva) becomes sore and inflamed
What is the function of the tear glands?
They make a fluid that keeps the surface of your eye moist.
What is the structure and function of the fluid created by your tear glands?
Fluid contains enzyme, lysozyme which can kill bacteria
What is the function of your eyelids?
They wash the fluid created by tear glands across your eye when you blink
What is the function of your eyebrows, eyelashes and eyelids?
They keep dirt from landing on the surface of your eyes
True or false: The closer the receptor cells are together, the blurrier the image the brain creates.
False.
True statement: The closer the receptor cells are together, the clearer the image the brain can create.
What are the 3 types of cones that you get?
1) Red sensing cones (cones sensitive to red light)
2) Blue sensing cones
3) Green sensing cones
What colours do rods allow us to see?
Only black and white
What is the structure of cones and rods on the retina?
The cones are tightly packed together while the rods are further out on the retina and less tightly packed
What image do cones produce?
Sharp image in colour
What image do rods produce?
Less detailed image
What is the structure and function of the iris?
The iris is colourful, it contains pigment that absorbs light and stops it from passing through
What happens to the pupil in high light intensity?
The iris closes in, and makes the pupil small
Why does the pupil get smaller in high light intensity?
It stops too much light getting in and damaging the retina
What happens to the pupil in low light intensity?
The iris pulls back from the pupil, making the pupil larger
How is the iris able to adjust the size of the pupil? (Refer to the muscles in the eye)
The iris contains muscles
1) There are circular muscles arranged in circles around the pupil → when they contract → pupil gets smaller
2) Radial muscles run outwards from the edge of the pupil → when they contract → makes the pupil dilate
Why must refraction occur when light shines into the ey?
It must happen so that the light rays can be focussed exactly onto the retina for a clear image
What structure in the eye is responsible for refraction?
Most of it is done by the cornea
The lens makes fine adjustments
How much must light rays be bent when entering the eye for the following:
1) Distant object
2) Nearby object
1) Only need to be refracted slightly by the thin lens
Because: the distant object’s light rays are only diverging slightly
2) Need to be refracted inwards quite strongly by the thick lens
Because: the nearby object’s light rays are diverging greatly
(Both are mostly refracted by the cornea)
Explain how the thickness of the lens affects the bending of light rays:
Thicker the lens → the more it bends light rays
Thinner the lens → less it bends light rays
What holds the lens in position?
Suspensory ligaments
What changes the tension on the suspensory ligaments, and thus the shape of the lens?
Ciliary muscle
Explain what happens to the suspensory ligaments and the lens when the ciliary muscle contracts and relaxes:
Ciliary muscle contracts → Suspensory ligaments loosen → lens gets thicker
Ciliary muscle relaxes → Suspensory ligaments tighten → lens is pulled thin
Define hormones:
Chemicals that are produced by a gland and carried in the blood, which alter the activities of their specific target organs
Define endocrine glands:
Glands that secrete hormones
Define target organs:
Organs that’s activity is altered by hormones
Define adrenaline:
A hormone secreted by the adrenal glands, which prepares the body for fight/flight
Define tropisms:
A growth response by a plant, in which the direction of growth is related to the direction of the stimulus.
Define phototropism:
A response in which part of a plant grows towards/away from the direction from which the light is coming
Define gravitropism:
A response in which part of a plant grows towards/away from gravity
How are hormones carried through the body?
Passed from the glands into the blood and carried around the body in the blood plasma
What hormone does the adrenal gland secrete?
Adrenaline
What is the function of adrenaline?
Prepares body for vigorous activity
What endocrine gland secretes the hormones, insulin and glucagon?
The pancreas
What is the function of the hormone insulin?
Reduces the concentration of glucose in the blood
What is the function of the hormone glucagon?
Increases the concentration of glucose in the blood
What hormone does the endocrine gland, testis secrete?
Testosterone
What is the function of the hormone testosterone?
Causes the development of male secondary sexual characteristics
What endocrine gland secretes the hormone, oestrogen?
Ovary
What is the function of the hormone oestrogen?
Causes the development of female secondary sexual characteristics, and helps in the control of the menstrual cycle
How many adrenal glands are there?
2
Where are the 2 adrenal glands situated?
One above each kidney
Name 2 examples of how adrenaline aids the fight or flight response:
1) Your heart beats faster supplying your muscles with more oxygen for aerobic respiration so that your muscles have more energy and you can run away faster
2) Widens your pupils so that you can see the danger more clearly
Compare the nervous and endocrine system with 5 differences:
Difference 1
N) Made up of neurones
E) Made up of glands
Difference 2
N) Information transmitted in the form of electrical impulses
E) Information transmitted in the form of chemicals (hormones)
Difference 3
N) Impulses transmitted along neurones
E) Chemicals carried in blood plasma
Difference 4
N) Impulses travel very quickly, action is fast
E) Chemicals travel more slowly, so action is slower
Difference 5
N) Effect of a nerve impulse usually only lasts for a very short time
E) Effect of a hormone may last longer
What effect does adrenaline have on the liver?
It causes the liver to release glucose into the blood
Because this along with the extra oxygen (from the increased heart and breathing rate) allows muscles to increase their metabolic activity
What is a negative response when referring to tropisms (growth response)?
Growth away from a stimulus
What is a positive response when referring to tropisms (growth response)?
Growth towards a stimulus
What are two important stimuli for plants?
Light and gravity
Are shoots positively or negatively gravitropic?
Negatively gravitropic, because they grow away from the pull of gravity
Are roots negatively or positively gravitropic?
Positively gravitropic, because they grow towards the pull of gravity
Are shoots negatively or positively phototropic?
Positively phototropic, because they generally grow towards light
Why do shoots and flowers grow upwards?
Shoots need to reach sunlight, the more sunlight the better they can photosynthesise
Flowers need to be held up in the air, where insects/birds/wind can pollinate them
Why do roots grow downwards?
They grow down to anchor themselves in the soil
And to absorb water and minerals from between soil particles
Define auxin:
A plant hormone made in the tips of shoots, which causes cells to elongate
How does auxin move through the shoot?
It diffuses from the tip, into the rest of the shoot
How does auxin control positive phototropism in shoots?
Light shines onto a shoot from all around → auxin is distributed evenly around the tip of the shoot → cells elongate at the same rate → shoots grows straight upwards
Light shines onto shoot from one side → auxin at tip concentrates on shady side → cells on shady side grow faster than ones on bright side → so shoot bends towards the light