Neurobiology 1/2 Flashcards
(42 cards)
What is the neuron doctrine (circa 1894)
- the neuron is the structural and functional unit of the nervous system
- neurons are individual calls and are continuous
- neuron has 3 parts: dendrites, soma and axon
- conduction takes place in dendrites to axon direction
what is the role of the following parts of a neuron:
1. dendrites
2. axon
3. myelin
4. node of ranvier
5. terminals
- increase SA
- carries info
- improved conduction
- breaks myelin sheath
- synapse with other neurons
what is the difference between an oligodendrocyte and a Schwann cell
- oligodendrocytes are found in the central nervous system (the brain and the spinal chord), and can wrap themselves around multiple parts on different axons
- Schwann cells are found in peripheral NS and wrap around part of 1 axon
what is the role of astrocytes
- they respond to neurotransmitters
- they have glial transmitters which influence neuron activity
- engulf blood vessels in the brain
what is the role of microglial cells
- they can phagocytose dead cells
what are the 4 main types of cells found in the brain
- neuron
- oligodendrocyte
- astrocyte
- microglial cells
what is a ganglion
fusion of a bunch of neurons
what does the peripheral nervous system consist of?
- autonomic NS (involuntary)
- somatic NS (voluntary)
The spinal chord is split into 4 sections, what do each of the 4 sections control?
TOP SECTION
1. cervical nerves
2. thoracic nerves (chest) / abdominal nerves
3. lumbar nerves (leg)
4. Sacral nerves (bowel, bladder, sexual)
What protects the brain? Describe its structure
The meninges, very tough membranes that wrap around the brain
1. tough outer layer (dura mater)
2. arachnoid mater
3. Pia mater
What is the role of the ventricular system
- it is the main source of cerebrospinal fluid (CSF)
- renewed 4-5 times every 24 hours
- supplies brain and spinal chord with nutrients
- buffers change in blood pressure and protects the brain
- allows the brain to remain buoyant
In a lumbar puncture, what do the following colours mean:
1. clear and colourless
2. Red (with blood)
3. Yellow CSF
- healthyy :)
- there is a subarachnoid haemorrhage
- old blood or jaundice
In the brain stem and the cerebellum what are the roles of the following structures:
- midbrain
- pons
- medulla
- cerebellum
- visual and auditory info
- modifies medulla output
- respiration, cardiovascular function
- balance, fine movement, posture
what is the role of the following diencephalon structures:
- thalamus
- hypothalamus
- integrates sensory info
- autonomic ctrl, appetite, reproduction, homeostasis, endocrine control
what is the resting potential of the cell compared with outside the cell
-70 mV
Define the following:
- hyperpolarisation (-100)
- depolarisation (-30)
- membrane potential more negative
- making the membrane potential more positive
what does the resting membrane potential require, who discovered this?
- semi permeable membrane
- ionic concentration gradient
- metabolic processes (long term)
what are the following intracellular/extracellular concentrations of ions
- Na+
- K+
- Cl-
INTRACELLULAR
Na+ 12mM
K+ 125 mM
Cl- 5 mM
EXTRACELLULAR
Na+ 120 mM
K+ 125 mM
Cl- 5 mM
what is the equilibrium occurring at resting potential
- higher concentration of potassium ions outside the cell than inside
- movement of potassium ions inside the cell to fix chemical gradient creates electrical gradient that drives potassium ions to move the other way
what is the Nernst equation and what does it calculate
Ek = RT/ZF Log([K+] out/ [K+] in)
R= gas constant 8.31
T= temp
F= faradays constant 96485 C/mol
Z= valency
calculates the cell potential under non standard conditions
what maintains the ionic concentration in the cell
ATP dependent ion pumps
They pump out sodium ions and pump in potassium ions
what causes voltage gated Na+ channels to open
- synaptic transmission (EPSPs)
- sensory neurones
- intrinsic properties e.g. pacemaker
- experimental activity
what are the features of action potentials?
(2)
- they have a threshold
- all the same size
what two factors contribute to repolarisation
- Na+ channels close
- Voltage-gates K+ ions open, after a delay
