Coordinataion CH13 Flashcards
Define stimuli
Changes in an organisms environment are called stimuli
What are stimuli sensed by?
Receptors
How does the organism respond?
With Effectors
Define Coordination
Coordination is the way in which receptors pick up stimuli and then passes informatoin on to effectors
Describe the Nervous System
Fastest way of sending information from receptors to effectors. Nerves make up the nervous system
Describe the Endocrine Sysyem
Slower method. Uses chemicals such as hormones to send info from receptors and effectors
What are two types of effectors?
Muscles and glands
What is an Axon?
An axon is the longest fibre in the neurone
What are dendrites?
Dendrites are the shorter fibres in the neurone. These fibres receive signals from other neurones. These signals are called nerve impulses
What is Myelin?
myelin is an insulator that is made of fat and protein. It insulates the axon
What are Shwann cells?
Shwann cells make up the Myelin Sheath
What are the 2 nervous systems of the nervous system?
- The central nervous system
2. The peripheral nervous system
Describe the Central Nervous System
The CNS is made up of the brain, spinal chord and neurones. When a receptor senses a stimuli it sends an electrical impulse to the brain or spinal chord. The brain or spinal chord send and impulse to the appropriate effector
Describe the Peripheral nervous system
The PNS is made up of receptors and nerves
Describe a reflex arc
The pathway along which the nerve impulse passes - The sensory neuron - rely neuron - motor neuron.
What is a synaps?
A junction between two nerve cells, consisting of a minute gap across which impulses pass by diffusion of a neurotransmitter
How do nerve impulses travel from one neuron to the other?
In the vesicles of the axon of the sensory neuron are chemicals called neurotransmitters. When an impulse along the axon of the sensory neuron arrives, it causes the vesicles to move to the membrane and empty their contents ( neurotransmitters). The neurotransmitters diffuse across the synaps and attaches to the receptor molecule of the next neuron
What is the purpose of a synaps?
Synapses ensure that nerve impulses only travel in one direction
What is the part of the eye that contains receptor cells?
The Retina
How do we see images?
When light falls on the retina it sends an electrical impulse along the optic nerve to the brain which is interpreted as an image
What is the Fovea?
The part of the retina where the receptor cells are packed most closely together. This is the part of the retina where light is focused when you look straight at an object
What is the Blind Spot?
Where there are no receptors at the front of the optic nerve. If light falls here no image will be scene. No impulses will be sent to the brain via the optic nerve.
What are the 2 kinds of receptor cells?
Rods and cones. Rods helps to see shades og gray and white. Cones helps to see colour.
What 3 colours can cones sense?
Red
Green
Blue
