Neurons Flashcards
What are the major parts of a Neuron?
- Cell body
- Dendrites
- Axon
- Presynaptic terminal
What is a Neuron?
A Neuron is a specialised cell used for transmitting nerve impulses
What is the axon?
The axon is the information sender of the Neuron, conveying an impulse toward other Neurons
What is a myelin sheath?
A myelin sheath is an insulating material that covers the axon, it has interruptions know as nodes of ranvier.
Where and what is a presynaptic terminal?
The pre synaptic terminal is at the end of the axon. This is the point from which the axon released chemicals that cross through the junction between one Neuron to the next.
What is the different between an afferent axon and an efferent axon?
An afferent axon brings information to a Neuron; an efferent axon carries information away from a Neuron.
What builds the myelin sheath?
Oligodendrocytes in the brain and spinal cord and Schwann cells in the periphery are specialised types of glia that build the myelin sheath.
What is Extracelluar fluid?
Fluid outside the cell
What is intracellular fluid?
Fluid outside the cell
What are examples of fluid with the cell?
Sodium, potassium and chloride
What are ions?
Molecules with an electrical charge
What is an anion?
A negatively charged ion (Cl -)
What is a cation?
A positively charged ion (Na + K +)
What is the charge of a resting potential?
-70 my
What is the charge of the action potential?
+40 my inside the Neuron
What is electrostatic force?
Two ions with the same charge will repel each other
What is diffusion?
Ions move from area of higher concentration to area of lower concentration
What is the sodium potassium pump?
A membrane protein which removes sodium
What are channels?
Small pores on the membrane which are closed when neurone is at rest. When the neurone receives a signal, sodium channels open causing sodium to enter the neurone - if enough sodium channels open and the inside becomes - 60 my then an AP will fire - more sodium channels open and sodium rushes in causing the inside of the cell to become + 40 mv relative to outside of the cell
What happens at the presynaptic terminal?
AP arrives at the pre synaptic terminal and causes calcium channels to open - calcium influx causes the vesicles to fuse with pre synaptic membrane and the neurotransmitters are released in to the synaptic cleft. This is called exocytosis. Neurotransmitters diffuse across the synaptic cleft and attached to receptors on the post synaptic membrane
What are receptors?
Receptors are membrane proteins which open ion channels
What are agonists?
Agonists are drugs which mimic and potentials neurotransmitters action
What are antagonists?
Antagonists are drugs which block and reduce neurotransmitters action
What is an IPSP?
Inhibitory post synaptic potential - if channel let sin negatively charged ions it makes the neurone less likely to fire
What is an EPSP?
Excitatory post synaptic potential - lets in positively charged ions and makes neurone more likely to fire.
What are the key cells used in vision?
- Photo pigment cells - rods and cones - catch light make bipolar cells fire
- Bipolar cells - first Neuron - passes signal on to ganglion cells
- Ganglion cells - pass signal on via optical nerve
- Opitcal cells via visual cortex via thalamus
What is the difference between rods and cones?
Rods - black and white - more in periphery of retina good for dim light.
Cones - blue green and red part of the light spectrum - more in centre of retina.
What are the different cell types in the retina?
Midget (small) - parvocellular pathway - detail from cones
Parasol (large) - mango cellular pathway - less detail from rods
What are the main visual areas?
The primary visual cortex - (V1, V2)
ventral stream - temporal lobe (object recognition)
Dorsal stream - parietal lobe (spatial qualities)
What is the function of area V1?
First level of input to visual cortex
Cells in v1 respond differently to different aspects of the visual signal
Involved in categorisation rather than analysis
B1 sends independent outputs to several other areas
What is the function of area V2?
Area V2 fills in the gaps of the visual field
What is the function of area V3 and V3A
First stage of building of object form
Code for component aspects of object recognition
Feeds information to V4, V5
What is the function of area V4?
Colour recognition
Individual neurones in V4 respond to a variety of wavelengths in addition to coding for orientation
What is the function of area V5?
motion perception
What is the function and where is the fusiform gyrus?
Primarily responsible for recognising faces, colours, words and bodies
What is a sulcus? (Sulci)
A suclus is a depression or grove in the cerebral cortex
What are and where are fissures?
Fissures similar to sulci are grooves in the cerebral cortex to create more surface area. Fissures are deeper groves. Fissures separate the brain in to the four lobes.
What is the primary function of the front cortex?
Motor planning, prediction, problem solving, attention, impulse control.
What is the function of the parietal lobe?
Deals with somaotosensory input, touch, sensory memory
LH - maths, language
RH - imagery, visualisation
What is the function of the temporal lobe?
Hearing, memory, speech centre, integration of multiple sensory functions
What is the function of the occipital lobe?
Movement, colour, visual field.
