Coordination and Response Flashcards
Receptors
Cells which senses stimuli
Coordination
The method where receptors pick up stimuli and passes information to the effectors
Two ways of sending information from receptors to effectors
- Nerves
- Hormones
Neurons
Contains the same basic parts of a cell (Cytoplasm, nucleus and cell membrane). They are present in long chains, in order to pass messages quickly throughout the body.
Dendrones/Dentrities
The shortest fibre from the thin fibers stretching out of the neuron cell.
Mylein
A layer of fat and protein which wraps the nerve fibers of active animals
Function of mylein
Mylein insulates the nerve fibres, so that they can carry the electrical impulses faster.
Central Nervous system
Consists of the brain and spinal cord, and is made up of neurons, its role is to coordinate the messages travelling through the nervous system. When stimuli detected, sendory neuron sends electrical impulses to brain or spinal cord, which sends impulses to the appropriate effector.
Reflex arc and how it works
When your hand touches a hot plate, the sensory receptor sends a impulse to your signal cord or brain through the sensory neurons along the axon. In the sensory neuron, the impulse is passed to relay neurons because they relay the impulses on to other neurons, this impulse is passed to the brain which again send a impulse through the axon of a motor neuron to trigger muscle cells to contract.
Voluntary and involuntary action
Voluntary action: when an action is produced with the involvement of thoughts, they are called voluntary action. Involuntary actions: actions which take place without consciousness or willingness of an individual are called involuntary actions.
Synapses
a junction between two nerve cells, consisting of a minute gap across which impulses pass by diffusion of a neurotransmitter.
Synaptic clefts
The small gap between the place where neuron meet.
The path taken by impulses
Vesicles in the axon of a neuron, contain transmitter senders, which are bubbled inside the vacoule, which then empties the content into the synaptic cleft. The neurotransmitter diffuses across the tiny gap and attaches to receptor molecules in the cell membrane of the relay neurone. The triggered relay neuron send impulses until the next synapses.
Sense organs
Groups of receptor cells responding to specific stimuli
Structure of the eye
Each eye is in a bony socket of the skull called orbit, The front of the eye is covered in a thin transparent layer called conjunctiva, which is kept mosit by a fluid made in tear glands and contains lysozyme which kills bacteria.
Sclera
A tough coat surrounding a part of the eye inside the orbit.
The retina
The part at the back of the eye, as light falls on the receptor cells, it send a electrical signal to the brain through the optic nerve, the brain sorts out all the impulses received by different receptors, some which are sensitive to light color changes, to form an image.
Fovea
The part of the retina where cells are most packed together
Blind spot
The place where the optic nerve leaves the eye, where if light hits, no impulses are sent.
Chronoid
Layer behind retina which absorb all the light that hits retina, so it does not travel all over the eye.
Two types of receptor cells in the retina
- Cones
- Rod
Rod Cells
Rod cells are sensitive to dim light, but doesn’t have the ability to sense change in light
Cone cells
Cone cells are able to distinguish between colors only when the light is bright
The iris
The circular piece of tissue at the front of your eye, it controls the amount of light sent to the retina, the wider it is more light is sent.
Accommendation
Adjustment to focus of light coming from different distances.
Gravitropism
A response in which a plant grows towards or away from gravity.
Phototropism
A response in which a plant grows towards or away from the direction from which light is coming
Auxin
Auxin is a hormone that is continuously produced by the tip cells and diffuses down to spread through the stem, Auxin makes the cells above it grow, so more auxin means faster the growth.
Auxin effect
If light shines to the stem from all direction, the auxin is distributed evenly across all sides, so growth is constant for all.
If light only shines from one side, the auxins move to the shady side causing the cells in the shady side of the plant to grow making the plant bend towards the side with light.
Etiolation
flowering plants grown in partial or complete absence of light. It is characterized by long, weak stems; smaller leaves due to longer internodes; and a pale yellow color (chlorosis).
Weedkillers
The selective weedkiller contains a growth hormone that causes the weeds to grow too quickly and die. Selective weedkillers kill plants that some species of animals rely on as a food source. This can result in a reduction of biodiversity.
Hormone
A chemical substance produced by a gland, carried by the blood which alters activity for one or more specific target organs
