Weeks 1-2 (BMR) Flashcards
What is the functional unit of the nervous system?
A Neuron (nerve cell)
What is a glial cell?
Any of the cells in the nervous system that help support, connect and protect the neurons
What is matrix?
the extracellular components that give structural support to everything in the nervous system
What are the 2 types of signaling in the nervous system?
- Electrical signals (propagated in a single neuron).
- Chemical signals (between a neuron and another cell)
What are the chemical ligands used in the nervous system?
Neurotransmitters (NT)
Summarize the role of Ca++ in NT release
Depolarisation of the axon terminal activates voltage-gated Ca++ channels.
Ca++ enters the cell from the synapse & triggers exocytosis of synaptic vesicles.
What are the ionic concentrations around the cell membrane at rest?
high [Na+] extracellular
high [K+] intracellular
What happens at the neuron membrane when it receives either an excitatory or inhibitory stimulus?
If excitatory response, Na++ enters the cell, the potential moves toward 0mv = depolarisation.
If inhibitory response, e.g. Cl- allowed into the cell. membrane potential becomes more negative (hyperpolarisation)
Briefly describe summation
excitatory/inhibitory responses are not the result of a single binding event, but rather thousands at once -a combination of depolarizing and hyperpolarizing events.
If there are more depolarising events, the cell will approach the threshold value which allows an electrical signal to be carried within the neuron (action potential).
Describe the different involvement of chemically-gated and voltage-gated ion channels in generation of an action potential
chemically-gates channels are responsible for the initial, slower change in voltage -> enough to reach the potential threshold.
When the threshold is reached, the voltage-gates channels are then responsible for the fast & significant change required for the action potential.
Describe the major event at each point in the action potential
What are the 2 major divisions of the nervous system?
Central Nervous System & Peripheral Nervous System
What are afferent and efferent CNS signals
Afferent - sensory - towards CNS
Efferent - motor - away from CNS
Describe the 2 divisions of the efferent PNS?
Somatic = conscious, voluntary signals that target skeletal muscles
Autonomic = reflexive control that targets smooth & cardiac muscles, glands & adipose tissue
Describe the 2 major subdivisions of the Autonomic Nervous System
Parasympathetic = “rest & digest”, stimulating GIT etc. Effector is ACh
Sympathetic = Fight, Flight, Freeze, Fuck - stress response. Effector NT is NE or Epinephine (uses ACh between neurons)
The following physiological effects are suggestive of which division of the ANS?
-pupil dilation
-increased heart rate
-inhibits digestions
-relaxes airways
Sympathetic
The following physiological effects are suggestive of which division of the ANS?
-pupil constricts
-decreased heart rate
-constrict airways
-increase bile secretion & GIT motility
-pancreas enzyme release
Parasympathetic
Contrast the origin & structure of the sympathetic & parasympathetic nervous systems
Origin in CNS: Sympathetic from Thoracic & Lumbar segments. Parasympathetic from brainstem & sacral segments.
Ganglion location: Sympathetic ganglia chain close to the spinal cord. Parasympathetic ganglia close to or on target tissue.
Pathways: Sympathetic - short preganglionic & long postganglionic neurons. Parasympathetic - long preganglionic & short postganglionic neurons
What are the 3 interdependent components of homeostatic control mechanisms? (and a summary of their function)
- Receptor - detects change
- Integrating Centre - part of CNS, makes sense of the incoming signal from PNS
- Effector/Motor - allows response to be carried out to maintain homeostasis
What are 2 types of skeletal muscle reflex pathways?
Monosynaptic reflex:
Afferent sensory neuron synapses directly with efferent motor neuron (mono = 1 synapse)
Polysynaptic reflex:
Multiple synapses between sensory & efferent neuron, can have further input from CNS. Allows modification of reflex (poly = >1 synapse)
