8. nervous system Flashcards
Explain the functions of the nervous system
- receive sensory input
- integrate information
- Controlling muscles and glands
- Maintaining homeostasis
- Establish and maintain mental activity
divisions of the nervous system
- nervous system
- peripheral nervous system and central nervous system
- somatic, autonomic, enteric nervous system
- from each of the three there is motor (efferent) and sensory (afferent)
- comes from the motor of the autonomic nervous system sympathetic and parasympathetic
- Central nervous system
decision maker of the body
Brain and spinal cord
Peripheral nervous system
messengers sendings messages to brain and spinal cord
sensory receptors
Cranial nerves: 12 pairs
Spinal nerves: 31 pairs
Ganglia: collection of neuron cell bodies outside of CNS
Plexuses: extensive network of axons outside CNS
Somatic nervous system
voluntary
From the CNS to skeletal muscles
Skeletal muscle contracts
Single neuron, one synapse
Autonomic nervous system
involuntary
From the CNS to smooth or cardiac muscle or glands
Two neuron, two synapses
Enteric nervous system
nerve plexuses within the wall of the digestive tract
Sensory neurons connect digestive tract to CNS
Sensory division
Afferent
Collects input from specialised receptors
Transmits the input as electrical signals to CNS
Motor division
Efferent
Transmits electric signals form CNS to effector (muscles, glands)
Sympathetic
fight or flight response
Primes the body to act in threatening situations
Quicker response
Eg increased heart rate, sweating
Parasympathetic
rest and digest response
Relaxes the body inhibiting high energy functions
Slower response
Eg stimulates digestion
Differentiate between the somatic and autonomic nervous systems.
- Somatic nervous system
voluntary
From the CNS to skeletal muscles
Skeletal muscle contracts
Single neuron, one synapse - Autonomic nervous system
involuntary
From the CNS to smooth or cardiac muscle or glands
Two neuron, two synapses
Contrast the general functions of the CNS and PNS.
- Central nervous system
decision maker of the body
Brain and spinal cord - Peripheral nervous system
messengers sendings messages to brain and spinal cord
sensory receptors
Cranial nerves: 12 pairs
Spinal nerves: 31 pairs
Ganglia: collection of neuron cell bodies outside of CNS
Plexuses: extensive network of axons outside CNS
structure of neurons
Neuron - receive information, integrate it and send appropriate response to target
3 main parts
1. Neuron cell body (soma)
2. Dendrites
3. Axon
Neuron cell body (soma)
nucleus, nasal bodies, Golgi apparatus, mitochondria
Dendrites
highly branched extensions of cell body
Conduct impulses from other axons or nerve cell bodies towards the cell body
Flow of current from tip of dendrites to cell body
Axon
vary in length
Conducts nerve impulses away from the cell body to the presynaptic terminals
The axon branches out into axon terminals, at the end of these terminals are knobs called synaptic knobs
Synaptic knobs: axon endings
Myelin sheath: schwan cells around axon
Node of ranvier: area in between the schwan cells
Multipolar
Several dendrites and one axon
Bipolar
One dendrite and one axon
Retina or eye, nasal cavity
Unipolar
One axon split into 2
Sensory neuron
conduct action potential from sensory receptors to CNS
Afferent neuron
Axons found in CNS
cell bodies are outside the CNS in dorsal root ganglion
Motor neuron
conduct action potation away from CNS towards muscles or glands
Efferent neuron
Axon in muscle or gland
Cell bodies in the CNS
Interneuron
conduct action potential within CNS from one neuron to another
neuroglial cells in the CNS and PNS
CNS
- Microglial cells
- Oligodendrocytes
- Astrocytes
PNS
- Schwann cells
- Satellite cells
Microglial cells
in CNS
immune cells
Become active, mobile and phagocytic in response to inflammation
Phagocytose foreign substances, necrotic tissue, pathogens