Nervous system Flashcards
(16 cards)
What are the 2 nervous systems?
- The central nervous system (CNS) - the brain and spinal cord.
- The peripheral nervous system - nerve cells and sense organs.
Identify the components of the central nervous system and peripheral nervous system
Central Nervous System: Brain, spinal cord, relay neurons, motor neurons
Peripheral Nervous System: Nerve cells, sense organs, sensory neurons, motor neurons
What is the stimulus-response pathway?
The stimulus-response pathway is the process by which your body senses and reacts to changes around you.
What is the role of the stimulus-response pathway and how does it work?
Allows organisms to react to changes in their environment.
When something happens (e.g loud noise), receptors detect it. They send a message to your brain through nerves.
The brain then decides what to do and sends a signal to your muscles or glands (called effectors) to respond.
This quick communication helps keep you safe and allows your body to react to its surroundings.
How do you achieve homeostasis with the stimulus-response pathway
To be able to achieve homeostasis, any changes or variations (stimuli) in the internal environment need to be detected (by receptors).
This change is communicated to effectors which bring about a response.
Draw the stimulus-response pathway
Stimulus → Receptor → Sensory neurone → Central Nervous System (CNS) → Motor neurone → Effector → Response
Describe the steps involved in the stimulus-response pathway
- Stimulus: An external change occurs.
- Receptor: Specialised cells detect the stimulus and stimulate electrical impulses in response.
- Sensory neuron: Carries the impulse from sense organs (receptors) to spinal cord & brain.
- Central Nervous System: Relay neurons in the brain process these impulses and transmit nerve impulses within the CNS.
- Motor neuron: Carries impulses from the brain & spinal cord to muscles & glands.
- Effector: Produces a specific response to the stimulus.
- Response: The action performed by the effector in response to the stimulus.
What are the three main types of neurons?
Sensory
Motor
Relay (also called interneurons)
State the functions of sensory, motor and relay neurons
- Sensory neurons: Carry impulses from sense organs to spinal cord & brain.
- Relay neurons: Processes impulses in brain and spinal cord and connects sensory and motor neurons.
- Motor neurons: Carry impulses from the brain & spinal cord to muscles & glands
What features do the 3 types of neurons all have?
- Axon: A long fibre which is insulated by a fatty myelin sheath. They are long so they can carry messages up and down the body.
- Myelin sheath: Surrounds and insulates nerve fibers in the axon.
- Dendrites: Tiny branches at each end. These receive incoming impulses from other neurones.
- Soma: A cell body containing the nucleus and organelles,
where essential metabolic processes occur to maintain cell survival.
Draw and label sensory, motor and relay neurons
List some examples of stimuli
- Light: The sun
- Sound: A loud explosion
- Heat & cold
- Pressure
- Movement
- Pain
- Chemical substances: sweet, salty, bitter and sour
- Chemicals: odours
Identify the 5 sense organs that detect stimuli
Eyes, ears, skin, tongue and nose.
What are the 5 sense organs roles’ in triggering the organism’s response?
Eyes - Help organisms avoid danger by spotting it, guide movement and coordination.
Ears - Alert to sounds of danger, communication.
Skin - Protect from injury, detect environmental changes (e.g., cold or heat).
Tongue - Detects taste stimuli, helps reject harmful or spoiled substances, accepts or rejects food.
Nose - Detects harmful substances e.g smoke, spoiled food.
Describe a reflex action
A reflex action is an automatic response to stimuli. A reflex response is rapid and its function is protection.
The messages pass through a reflex arc.
Explain how a reflex action helps protect the body from harm
A reflex action helps protect the body from harm by providing a fast involuntary automatic response to a dangerous or harmful stimulus. It allows the body to react immediately, without needing to think about it, which reduces the risk of injury.
