What are the three stages of the nervous system?
- Sensory input
- Integration (decides on action)
- Motor output (action)
What’s different about sensory neurons?
Their cell body is halfway along their axon
What connects two cell bodies?
Synaptic terminals
What’s different about interneurons?
They have a very large number of dendrites
What is glia’s role in the brain?
It forms the structural integrity required
What are the two types of glia?
Astrocytes: Star like structure, in CNS, regulate concentrations of ions and compounds, form the blood-brain barrier (this stops large amounts of compounds from leaving blood vessels and entering the brain)
Oligodendrocytes: (CNS) and Schwann cells (PNS) = Form insulated myelin sheaths around axons (MS has inssues due to loss of these myelin sheaths)
Explain the sodium/potassium-ATPase
- Pumps against the concentration gradient
- Uses ATP for energy
- Pumps 3 sodium out and 2 potassium into the cell
What concentrations form the resting membrane potential?
Outside the membrane: 5mM K+, 150mM Na+, 120mM Cl-
Inside the membrane: 140mM K+, 15mM Na+, 100mM A- large anions
Why is the resting membrane potential negative?
- There are many K+ channels open
- This decreases the chemical gradient and increases the electrical gradient
- This does not depend on voltage-gated ion channels
What’s special about excitable cells?
They allow rapid change in membrane potential
Definition: Hyperpolarisation
Inside of cell becomes more negative
Definition: Depolarisation
Inside becomes more positive
