Coordination And Control Flashcards
What does coordinated mean?
The body is able to make things happen in different parts of the body at the right time
Humans & other animals have 2 organ systems which coordinate…
-the nervous system
-the endocrine (hormone) system
What three elements are needed for a coordinated response in an organism?
-stimulus
-receptor
-effector
What is phototropism?
the growth of a plant in response to the direction of light, where the plant grows towards the light source
Define “stimulus” in the context of a coordinated response.
-Change in the animal’s surroundings
e.g. a ball is thrown towards you
Define “receptor” in the context of a coordinated response.
-Is the organ which detects the change
e.g. your eye
Define “effector” in the context of a coordinated response.
-Muscles are the effectors & they contract as you catch the ball
How is the link between stimulus and response made?
-by the nervous or endocrine system.
What do receptors do when they detect a stimulus?
-Receptors detect the stimulus & convert its energy into nerve impulses.
Give an example of a sense organ acting as a receptor.
-The eye acts as a receptor by converting light energy into nerve impulses.
Eye: Converts ______ into nerve impulses.
Eye: Converts light into nerve impulses.
Tongue: Converts ______ into nerve impulses
Tongue: Converts chemical energy into nerve impulses
Ear: Converts ______ into nerve impulses.
Ear: Converts sound into nerve impulses.
Nose: Converts ______ into nerve impulses
Nose: Converts chemical energy into nerve impulses
Skin (touch receptors): Converts ______ into nerve impulses
Skin (touch receptors): Converts pressure into nerve impulses
Skin (temperature receptors): Converts ______ into nerve impulses
Skin (temperature receptors): Converts heat into nerve impulses
Central Nervous System
-consists of the brain & spinal cord
-the CNS coordinates all of the nervous such as moving or reflexes
Peripheral Nervous System
-The peripheral nervous system contains all of the other nerves
-Which send impulses to all the effectors
What connects sense organs & effectors?
Nerve cells (neurones) connect sense organs & effectors.
What are the three types of neurones?
-Sensory neurones
-Relay neurones
-Motor neurones
What is the function of sensory neurones?
-Carry impulses from receptors to the CNS (brain & spinal cord).
What is the role of relay neurones?
-Found in the CNS (brain & spinal cord).
-Transmit impulses from sensory neurones to motor neurones.
Nucleus
-Contains all the genetic information of the cell
Dendrite
-Tree like projections which connect to different neurones.
-One neurone can connect to many other neurones
Cell body
-The main section of the cell.
-Contains the nucleus
Axon
-The long section - electrical impulses travel long distances through the axon.
Myelin Sheath
-Insulates the axon
-Speeds up the transmission of the impulse.
What are reflexes?
-Automated actions
-Do not involve the brain
-Very fast responses
-Involve three types of neurones: sensory, relay, and motor
What is a reflex arc?
-The pathway of nerve impulses from receptor to effector
-Involves the detection of a stimulus and a response
-e.g. moving a hand away from heat
What happens when heat is detected?
-The receptors detect the change in temperature
-An impulse is sent along the sensory neurone
-The person quickly moves their hand away
-Describe the role of the sensory neurone in a reflex arc.
-Carries the impulse from the receptor to the spinal cord
What is the function of the relay neurone?
-Passes the impulse from the sensory neurone to the motor neurone
-Located in the spinal cord
-Transmits signals across synapses
What is a synapse?
-The gap between two neurones
-Where the impulse is transmitted from one neurone to another
What does the motor neurone do in a reflex arc?
-Carries the impulse to the effector
-Causes the effector (e.g., arm muscle) to contract
-Moves the arm away from the stimulus (e.g., fire)
-Shown in yellow in the diagram
What is the overall sequence of a reflex action?
-Stimulus detected by receptors
-Impulse travels along sensory neurone to spinal cord
-Relay neurone transmits impulse to motor neurone
-Motor neurone activates effector to produce a response
What is a synapse in the context of neurons?
- A synapse is a very small gap between two neurons.
- Neurons do not make direct contact at the synapse.
- Signals need to cross the synapse to continue their journey to or from the CNS (central nervous system).
Describe the process of neurotransmission.
- An electrical impulse travels along an axon.
2.This triggers the nerve-ending of a neuron to release chemical
messengers called neurotransmitters.
3..These chemicals diffuse across the synapse (the gap) and bind with receptor molecules on the membrane of the next neuron. - The receptor molecules on the second neuron bind only to the specific
chemicals released from the first neuron. This stimulates the second neuron to transmit the electrical impulse.
What does the eye do as a sensory organ?
-Detects light
-Sends an impulse to the brain
-Brain converts the impulse into an image, this is what you see
What happens to the eye in dim light?
-Radial muscles contract
-Circular muscles relax
-Iris becomes narrower
-Pupil dilates
What happens to the eye in bright light?
-Circular muscles contract
-Radial muscles relax
-Iris becomes wider
-Pupil constricts
What is the reflex arc for adjusting to light intensity?
-Retina detects light intensity
-Effectors are the iris muscles
-Adjusts pupil size in response to light
What is accommodation in the eye?
The changes that take place in the eye which allow us to see objects at different distances
How does the eye focus on a distant object?
- Light rays entering the eye are almost parallel when they reach the cornea.
-The lens does not need to refract the light much to ensure it focuses onto the retina - Ciliary muscles relax.
- Suspensory ligaments are pulled tight.
- Lens becomes thin and less convex.
- Less refraction of light is needed to focus onto the retina.
How does the eye focus on a close-up object?
- Light rays entering the eye are diverging (spreading out).
-The lens needs to refract the light to ensure it focuses onto the retina - Ciliary muscles contract.
- Suspensory ligaments become slack.
- Lens is not stretched, becoming thicker and more convex.
- More refraction of light is needed to focus onto the retina
