Nervous System Overview
What are the two divisions of the central nervous system?
Brain and spinal cord
Neurons found completely within the CNS and handle the integrative functions of the nervous system are called what? What are the accessory cells in the central nervous system that support neurons called?
interneurons, neuroglia or glia or astrocytes
What type of channels contribute to the resting potential since they are open at rest?
Leak channels
What are two types of synapses?
1. Chemical (neurotransmitters) 2. Electrical (gap junctions)
Inflammation of the membranes around the spinal cord and brain is known as what?
Meningitis
Describe the 2 divisions of the autonomic nervous system.
1. Sympathetic: stimulates organs during stress - "fight or flight" 2. Parasympathetic: stimulates organs during periods of rest - "rest and relaxation"
What cell produces myelin in the CNS? In the PNS?
CNS: Oligodendrocytes PNS: Schwann Cells
Define resting membrane potential. About what is it in mV in a normal neuron?
The voltage of the cell at rest. It's about -70mV.
Name 3 ways in which neurotransmitters are removed from the synaptic cleft.
1. Diffusion 2. Enzyme degradation 3. Re-uptake by cells
Where is grey matter in the spinal cord? White matter? Is this similar or different to where it is located in the brain?
Grey matter is in the center of the spinal cord with white matter surrounding it. It is different to the brain which has grey matter on the outside and white matter on the inside.
There are 2 types of nerves in the PNS. Nerves sending information towards the CNS are called ________ and they carry __________ impulses. Those sending it away from the CNS are called _________ and carry _______ impulses.
Afferent (sensory) Efferent (motor)
Name 3 types of glia cells and their functions.
1. Astrocytes: star-shaped cells in the CNS that provide support and form the blood-brain barrier 2. Oligodendrocytes: Form myelin in the CNS 3. Microglia: function as phagocytes 4. Ependymal cells: Help move CSF 5. Schwann cells: Produce myelin in the PNS 6. Satellite cells: Surround and support neurons in the PNS
In a resting neuron, what positive ion is in greater concentration inside the neuron? Outside the neuron?
Inside: Potassium Outside: Sodium
What 2 things happen at the peak of an action potential to stop an action potential?
K+ channels open, Na+ channels inactivate
What are the 3 meninges around the brain and spinal cord from most superficial to deepest?
1. Dura mater 2. Arachnoid mater 3. Pia mater
What are 3 differences between how the endocrine system regulates homeostasis and how the nervous system regulates homeostasis?
Endocrine: Responses are slow, widespread, and long-lasting Nervous: Responses are fast, local, and short-lasting
What are the 3 divisions of "neuron type" when classified by structure?
1. Multipolar neurons:Several dendrites and one axon (most neurons in the CNS) 2. Bipolar neurons:One dendrite and one axon 3. Unipolar neurons: One process extending from the cell body with 2 branches (always sensory neurons, as in the dorsal root ganglia)
What are graded potentials? What kind of channels produce them? Can they vary in size? Can they be positive (depolarizing) and negative (hyperpolarizing)?
Graded potentials are subthreshold potentials caused by the opening of ligand-gated or mechanically-gated channels. They can vary in size and can be depolarizing (excitatory post-synaptic potentials, EPSPs) or hyperpolarizing (inhibitory post-synaptic potentials, IPSPs).
Describe the steps that occur at a chemical synapses in order to transmit a signal.
1. An action potential arrives at the pre-synaptic terminal, which causes 2. Voltage-gated Ca+ channels to open, which causes 3. Vesicles to move to the axon terminal and neurotransmitter to be released. 4. Neurotransmitters diffuse across the synaptic cleft and 5. Bind to ligand-gated ion channels, causing a change in the membrane potential of the post-synaptic neuron
What are the 3 spaces found around the meninges called (from most superficial to deepest)? What is each space filled with?
1. Epidural space (between verebra and spinal cord): Filled with fat 2. Subdural space (between dura and arachnoid mater): Filled with nothing! 3. Subarachnoid space (between the arachnoid and pia mater): Filled with CSF
What are the 3 divisions of the the peripheral nervous system? What is the function of each division?
1. Somatic: Includes conscious sensory input and voluntary motor output 2. Autonomic: Includes unconscious sensory input and involuntary motor output 3. Enteric: Brain of the gut
Draw a picture of a neuron. Include, and label in the picture the following structures and describe their function: cell body, dendrites, axon, axon hillock, axon terminal, nodes of ranvier, myelin
Describe what summation is and the two types of summation that can occur.
Summation is when graded potentials add together. Spatial summation is when graded potentials from 2 different synapses add together, and temporal summation is when graded potentials from the same synapse occur in rapid succession and add together
Describe the main difference between depolarization and repolarization of a nerve cell, including the changes observed in the membrane potential and the specific movement of ions involved (which ones and in which direction).
Depolarization: membrane becomes MORE POSITIVE, SODIUM IONS are rushing IN Repolarization: membrane becomes MORE NEGATIVE, POTASSIUM IONS are moving OUT
Define the following: 1. Conus medullaris 2. Filum terminale 3. Cauda equina 4. Cervical enlargement 5. Lumbar enlargement
1. Tapered portion at the bottom of the spinal cord 2. Connective tissue at the end of the spinal cord that extends to the coccyx. 3. Nerves that arise from the lower part of the spinal cord. 4. Expansion of the spinal cord for the peripheral nerves of the upper extremities. 5. Expansion of the spinal cord for the peripheral nerves of the lower extremities.