Nervous System Flashcards
Neuron
nerve cell
Nerve fibre
Any long extension of cytoplasm from a nerve cell body (axon)
Nerve
A bundle of nerve fibres surrounded by connective tissue
Multipolar Neurons
1 axon, multiple dendrites
Motor Neurons
Bipolar Neurons
1 axon, 1 Dendrite
Ear, Eye, Nose
Unipolar Neurons
Cell body to one side of the axon
Sensory Neurons
Central Nervous System
Brain and spinal cord
Peripheral Nervous System
Nerves, Receptors, Muscles, Glands
Synapse
Gap between the end of one neurons dendrite and another neurons axon or cell body
Outline the steps in the transmission across a synapse
- A nerve impulse reaches the axon terminal, activating voltage gated sodium ion channels.
- There is a higher concentration of calcium ions in the extracellular fluid, which flow into the cell at the presynaptic axon terminal.
- Synaptic Vessicles fuse to the membrane releasing neurotransmitters via exocytosis
- THe neurotransmitters diffuse across the gap attaching to the next neurons membrane
- Ligand-gated portein channels are stimulated open, allowing an influx of sodium ions and intiates an action potential in the postsynaptic axon terminal. Neurotransmitters are reabsorbed via enzyme degregation or diffusion.
Outline the steps in the transmission of impulses
- Positive outside, negative inseide (-70mv) at rest in the nodes of ranvier
- A stimulus large enough to break the threshold (15mv) causes voltage gated sodium channels to open allowing soidum ions to move into the neuron
- Depolarisation occurs at the nodes of ranvier
- Sodium channels in the next node are triggered open
- Repolarisation occurs as sodium channels close, potassium channels open and potassium ions move out of the neuron.
- Hyperpolarisation occurs as a potassium channels close and sodium/potassium pumps work to bring the membrane back to resting potential (-70mv)
- Action potential jumps from node to node (a saltatory conduction occurs)
Unmyelinated Nerves
-Depolarisation causes the action potential to flow onto the membrane immediately adjacent to the stimuus
- Nerve impulse travels the whole length of the axon
- Lower concentration gradient of ions on either side of the membrane
-Nerve impulse is slower
Myelinated Nerves
Depolarisation causes the action potential to jump from node to node
- Nerve impulse only occurs at nodes of ranvier
- Higher concentration gradient of ions on either side of the membrane
Nerve impulse is faster
Afferent (Sensory): Somatic
Carries impulses from receptors around skin and muscles to the CNS
Afferent (Sensory): Visceral
Carries impulses from internal organs to the CNS
Efferent (Motor): Somatic
Carries impulses from CNS to skeletal muscles
- 1 nerve fibre
- No synapse or ganglion
- Acetylcholine at the neuromuscular junction
- Always excitation
Efferent (Motor): Autonomic
Carries impulses from CNS to the heart and other involuntary muscles
- 2 nerve fibres
- Synapse and Ganglion
- Sympathetic (Noradrenaline)
- Parasympathetic (Acetylcholine)
- Excitation or Inhibition
Sympathetic
Flight or fight response (prepares body for strenuous activity)
Parasympathetic
Rest or digest (rest and quiet situations)
How many cranial nerve pairs are there?
12 pairs
How many spinal nerve pairs are there?
31 pairs
Cerebral Cortex
Outer surface of the cereberum
made of grey matter
In charge of higher order functions
Frontal Lobe
Thinking, problem solving, personality, emotions, movement control
Temporal Lobe
Processing memories, linking them to senses, auditory information
Parietal Lobe
Processing temperatures and senses
Occipital Lobe
Vision
Insula Lobe
Recognition of senses, emotions, addictions, psychiatric disorders
Corpus Callosum
Nerve fibres that allow for communication between the two hemispheres
Cerebellum
Allows for fine controlled movements, balance and posture
Hypothalamus
Maintains homeostasis
Medulla oblongata
Regulates heart, breathing, diameter of blood vessels
Spinal Cord
Grey matter surrounded by white matter
Made of:
Ascending Tracts - Sensory axons sending impulses to the brain
Descending Tracts - Motor axons delivering impulses from the brain to muscles
Spinal Reflexes
Longitudinal Fissure
Deepest fissure, seperates the cerebrum in half
Gyrus (Convolutions)
FOlds on the surface of the cerebrum
Sulci
Shallow downfolds on the surface
Fissures
Deep downfolds
Sensory Areas
Interpret impulses from receptors
Motor Areas
COntrol muscular movements
Association Areas
Intellectual and emotional processes
Thermoreceptors
Detect changes in temperature
Found in: Hypothalamus (Central; recieves information from peripherals), Skin (Peripheral; 2 types, cold and hot)
Osmoreceptors
Detect osmotic pressure (concentration of susbstances dissolved in the water of plasma)
Found in: Hypothalamus
Chemoreceptors
Regulateion of chemicals in the body (pH levels)
Found in: Nose, Mouth, Blood Vessels, Medulla oblongata
Touch Receptors
Respond to touch
Found in: Skin
Pain Receptors
Respond to damaged tissue
Found in: Skin, Mucous Membranes, Most organs (NOT BRAIN)
Reflex
A rapid, autonomic response to a change in the environment
Properties of a reflex
- Rapid
- Involuntary
- Require a stimulus
- Stereotyped
Innate Reflexes
Response to a stimulus that is acquired genetically
e.g Suckling reflex
Acquired Reflexes
Response to a stimulus that is learnt
e.g. catching a ball
