Nerves and Muscles

• What does the central Nervous system include and what are its constituent cells?

  The brain and the spinal cord. The constituent cells are Neurons and Gila
• What does the Peripheral nervous system consist of, and what are its constitue cells?

  Peripheral nerves and ganglia, Constituent cells are Neurons and gila
• In the CNS what are groups of cell bodies called, bundles of axons, and there counterparts in the cerebral cortex and spinal cord?

  Nucleus (grey matter), Tract (White matter)
• In the PNS what are groups of cell bodies called, what are bundles of axons called?

  Ganglion, Nerve
• What are the four regions of a neuron, and what are there functions?

  Dendrites [Recivie signals], cell body [Sums input], Axon [Carries signal], Axon terminal [Converts signal to chemical signal].
• What part of the cell sums the signals?

  Axon hillock
• What are the four morphological types of neurons?

  Mulipolar, Unipolar, Bipolar, Anaxonic (axonless)
• What is the function of Astrocytes? ⭐

  Supply nutrients to neurons, Ensheath blood capillaries and injury response in the CNS
• What is the function of Microglia?


  Immune cells of the CNS, engulfing microorgaisms and debris

  
• What is the function of Ependymal cells?

  Line the fluid-filled spaces of the brain and spinal cord, cilia circulate the CSF.

  
• What is the function of the Oligodendrocytes?


  Support nerve fibres, ensheaths axons with myelin in CNS

  
• What are Schwann cells?

  Cells of the PNS which produce the myelin and support the nerve fibres. Similar to oligodendrocytes.
• What are nodes of Ranvier and what is their function?

  Gaps in the Schwann cells where the axon is exposed, increases the conduction velocity.
• What are myelin sheaths made of, and what is there function?

  Fat. They wrap around axons, preventing leak channels from working, and create a large concentration gradient, meaning that the ions diffuse down the axon quicker, so the signal travels faster.
• What is the gap between the axon terminal and the dendrites of the next axon called?

  Synaptic Cleft
• What is the term for infomation entering and exiting the brain?

  Infomation entering the brain is called Afferent (Accending), while information exiting the brain is called Efferent (Descending).
• What are the two types of infomation in and what are some examples?

  Somatic, voluntry muscle contraction, and autonomic, involuntary muscle control.
• How many neurons are in the somatic efferent division, and where are they located?

  There are two, The upper motor neuron, with its body in the brain and axon in the spinal cord, and the cell body in the spinal cord and the axon in the spinal nerve.

  
• What system doesn't use acetyl choline as a neuron transmitter?

  The signal from the sympatheitic nervous system to the effector (Norepinephrine).
• List some features of synaptic efferent division:

  Voluntary movement, Two neurons between brain and effector (upper and lower motor neurons), axons are myelinated, the neurotransmitter is acetyl choline, the effector is skeletal muscles.
• Describe the anatomy in the autonomic nervous system.


  There are three neurons, With neuron #1 having its body in the brain and axon in either the brain or spinal cord (CNS). Neuron #2 has its body in the brain or spinal cord (CNS) and axon in the PNS. Neuron #3 has its body & axon in the PNS.
• What are some properties of Neruon #2 in the autonomic nervous system?

  Its body is in the central nervous system, it has a myelinated axon that extends into the PNS & synapses to the autonomic ganglion. It is a pre-ganglion neuron & uses Acetyl Choline.
• What are some properties of Neuron #3 in the autonomic nervous system?

  Its body is in the PNS, in an autonomic ganglion. The axon is in the PNS & is unmyelinated. Its synapse is on the effector organ and uses either acetylcholine (Parasympathetic) or Norepinephrine (Sympathetic). It is post ganglion neuron.
• What is the difference between the Sympathetic and Parasympathetic nervous systems?

  Sympathetic is for fight or flight response (Norepinephrine), Parasympathetic (Acetyl Choline) is for the rest & digest response.See an expert-written answer!We have an expert-written solution to this problem!
• Where does the sympathetic nervous system exit the CNS?

  The thoracolumbar region of the spine
• Where does the Parasympathetic nervous system exit the CNS?

  The cranial and sacral region [Craniosacral]
• What is the structure called made out of sympathetic ganglia?

  Sympathetic ganglion chain
• What voltage stimulates the axon hillock?

  -60mV
• What are the three types of gated ion channels?

  Chemically, Voltage & Mechanical
• What mantians the resting membrane potential?

  Sodium Potassium Exchange Pump
• At resting membrane potential, what has a higher potassium and sodium concentration?

  Potasssium concerntration higher inside cell, Sodium concerntration higher outside cell.
• What occurs during an Excitatory (EPSD) local potential?

  Neurotransmitters (Acetyl Choline & Norepinephrine) are released, binding to chemically gated Na+ channels, causing a depolarisation.
• What occurs during an inhibatory (IPSD) local potential?

  Nuerotransmitters (GABA) are released, binding to chemically gated K+ channels, causing a hyperpolarisation.
• What are the properties of the two different types of summnation?

  Spatial summation - summing local potentials from multiple pre synaptic neurons. Temporal summnation - summing repeated fire from one presynaptic neuron.
• What is the order of events that cuase an action potential?

  1. When the required membrane potential is reached, the axon hillock initiates the action potential.

  2. Voltage gated Na+ channels open when the voltage reaches -60mV, and sodium moves into the cell, causing a rapid depolarization phase of the action potential.

  3. At +30mV, the Na+ channels close, and Na+ stops entering the cell. Voltage gated K+ ion channels open, causing the repolarization phase of the action potential, where K+ moves out of the cell, bringing the membrane potential down. [VG K+ channels start opening at the same time as Na+ channels but are slower to open].

  a. Voltage gated Na+ channels begin to close

  4. Voltage gated K+ channels begin to close [They close slowly]. This allows excess K+ to exit, causing the hyperpolarisation phase of the action potential.

  5. When all voltage K+ channels close, the membrane returns to -70mV.
• What happens when the action potential reaches the axon terminal?

  Voltage-gated calcium ion channels open, causing a rapid influx of calcium. Calcium interacts with neurotransmitter-containing vesicles, causing the vesicles to release neurotransmitters into the synaptic cleft.
• What is the difference between the absolute and relative refractory period?

  Absolute refractory period is when another action potenital cannot occur on the axon, and the reletive refractory period is requires a larger than normal stimulas to cause an action potential.
• Where does the spine start and finish?

  Starts at the foramen magna [Hole in base of spine] and terminates around the L1/L2 vertebrae.
• How many spine segments in each of the following regions? Cervical, Thoracic, Lumbar, Sacral & Coccygeal?

  8 [Cervical], 12 [Thoracic], 5 [Lumbar], 5 [Sacral], 1 [Coccygeal] - 31 pairs total.
• What is the end of the spinal cord called?

  Conus medularis.