3.2 the nervous system Flashcards
The nervous system is composed of the central nervous system and the peripheral nervous system. Compare the structure and function of sensory neurons, interneurons, and motor neurons. Describe the structure of a nerve pathway from receptor to effector. Describe the role of synapses and neurotransmitters. Describe the role and pathway of reflex responses.
What is the nervous system?
Nervous system is made up of two systems the central nervous system and the peripheral nervous system and is responsible for detecting and responding to stimuli.
The nervous system’s repsonses are involved when more rapid and direct communication is required and do so through electrical messages.
What is the central nervous system?
The central nervous system (CNS) consists of the brain and spinal cord and principally stores, arranges and manages information.
How can the CNS be subdivided?
- Brain (controls the CNS)
- Spinal cord (link between brain and peripheral nerves)
What is the peripheral nervous system?
The peripheral nervous system (PNS) is composed of cranial, spinal and peripheral nerves which carry information between the outer and inner organs.
How can the PNS be sub-divided?
- Somatic (voluntary): under our conscious control e.g. moving the skeletal muscles
- Automatic (involuntary): under our unconscious control e.g. change in heart rate.
How can the automatic nervous system be subdivided?
- Sympathetic nervous system: mobilises body systems (fight or flight response)
- Parasympathetic nervous system: conserves energy, maintains quiet state (rest and digest response).
What are neurons?
Neurons are nerve cells that send messages all over your body to allow you to do everything from breathing to talking, eating, walking, and thinking.
What are three types of neurons in the nervous system?
- Sensory neurons: nerve cells which transmit information from a receptor to the CNS.
- Interneurons: located in the CNS and transmit information from sensory neurons to motor neurons.
- Motor neurons: transmit messgaes from CNS to the effectors that are typically muscles or glands.
What are the three main components of a neuron?
- Dendrites: recieves impulses from sensory receptors or other neurons and transmits the infromatio towards the cell body.
- Cell body: cell body contains many organelles, including a nucleus, endoplasmis reticulumn and mitchondria.
- Axons: long extensions of the nerve cell, which transmit infromation to another cell or receptor. typically quite long.
Whats a mylin?
The main function of myelin is to protect and insulate these axons and enhance the transmission of electrical impulses. If myelin is damaged, the transmission of these impulses is slowed down, which is seen in severe neurological conditions such as multiple sclerosis
Describe the structure of a sensory neuron.
A sensory neuron has a cell body joined by a dendron and axon.
Describe the structure of a interneuron.
A interneuron has short axons, enabling connections between a sensory neuron and a motor neuron.
Describe the structure of a motor neuron.
A motor neuron has a cell body at the end, and long axon and short dendrites.
How do neurons transmit messages in the form of electrical impulses?
Neurons transmit messages to specifc destinations in the form of electrical impulses. Chaning concentration gradients of sodium to potassium ions to do. As the nervous impulses involves changing sodium and potassium concentrations energy is required for active transport to move these ions against the concentration gradient.
What is a synapse?
The junction between neurons is called a
synapse
A nerve impulse will release
neurotransmitters (through exocytosis) which diffuse across the space (synaptic cleft) and bind to receptors on the next
neuron
The next neuron will then transmit a nerve
impulse
