Nervous Tissue- Week 10 Flashcards
Describe how nerve cell’s structure and cytology are specialised for their role.
Specialised for sending & receiving
signals
Identify the roles of glial cells.
Provide support functions
▪ Out number neurons 10 to 1
what are the 4 domains (parts) of a nerve cell
- axon
- dendrites
- cell body
- pre-synaptic terminals
what is the function of the axon in a nerve cell
Message sending – action potentials
what’s the function of dendrites in a nerve cell
Info receiving area
▪ Covered with receptors
what are the functions of the cell body of a nerve cell
Integrates inputs & generates signals
▪ Synthesis & processing of proteins
what are the functions of the pre-synapse of a nerve cell
▪ Release of neurotransmitter (NT) – synaptic transmission
(Terminal of axon – multiple endings)
what are the 4 Specialised cytology of nerves
▪ Large nucleus
▪ Abundant ER, mitochondria & lysosomes
▪ Well developed golgi complex
▪ Cytoskeleton (Neurofilaments, Microtubules)
what are the glial cells found in the central nervous system (CNS) and there functions- give 3
- Astrocytes: provide nutrients,
regulate conc. of ions, structural support, key cell in the blood-brain barrier
-Microglia; scavenge & degrade dead cells,
protect brain from microorganisms
-Oligodendrocytes – form myelin sheaths in CNS
what are the glial cells found in the peripheral nervous system (PNS) and there functions
- Satellite cells- provide nutrients & structural support
- Schwann cells – form myelin sheaths
in PNS
Identify the deflections in an action potential
Excitatory and inhibitory graded potentials cancel each other out- EPSP-IPSP cancellation
As the voltage difference between two electrodes (one in the neuron and one outside) changes, If the inside becomes more negative, compared to the outside, it cancels each other out and threshold isn’t reached
what is the resting membrane potential inside a cell
-70 mV
how is the Na+ and K+ concentrations maintained/ regulated
by ATP Na+/K+ pumps
what ion is has the highest concentration in the:
1) intracellular fluid
2) extracellular fluid
1) Potassium ions
2) Sodium ions
what is the number to reach threshold potential
-50 mV
what happens in depolarisation
mass opening of sodium channels- travels down its conc as its stimulated down its conc into the intracellular fluid/enters the cell
what happens in repolarisation
Sodium ion channels close
Potassium ions open
Potassium ions leave the cell- as its positive charge leaving the cell it causes the membrane potential to plummet
what is the refractory period
its a period of time when the sodium ion channels can’t be stimulated again, they have to come out of the refractory period to be stimulated again
(stops us from having a continuous line of action potentials)
what happens during hyperpolarisation
(when the charge of membrane declines too much- more than -70mV due to K+ leaving)
- some Potassium ion channels remain open
- ATP- Na+/K+ pump restores resting potential (Na+ pumped out & K+ pumped inside the cell)
EPSP-IPSP cancellation
Excitatory post synaptic potential - Inhibitory post synaptic potential
how are excitatory and inhibitory signals summated
-Spatial summation: excitatory potentials from MANY neurons trigger threshold
-Temporal summation: Many excitatory potentials from ONE neuron triggers threshold
Compare and contrast chemical and electrical signals
▪ Chemical synapse – delay of ~1ms
▪ Electrical synapse faster
▪ Chemical synapse – delay of ~1ms
▪ Electrical synapse faster
▪ Chemical synapse – potential for
signal modulation
▪ Electrical synapse – signal relay
*similarity is that they both relay information
