Neural Transmission

Question 1

Types of slices

Answer 1

Horizontal (flat across), Sagittal (backwards) and Coronal (from right to left)

Question 2

Directions

Answer 2

Dorsal = op,
Ventral = bottom,
Superior = above,
Inferior = below,
Lateral = further from midline,
Medial = towards the midline,
Anterior = towards front,
Posterior = towards back.

Question 3

Brain structure

Answer 3

Gyrus = Protuberance on surface,
Sulcus = fold or groove separating gyri,
Fissure = long, deep sulcus.

Question 4

Location

Answer 4

Proximal = close to,
Distal = far from,
Ipsilateral = same hemisphere,
Contralateral = opposite hemisphere.

Question 5

CNS + PNS

Answer 5

CNS = Brain + spinal cord.

PNS = Somatic nervous system (voluntary muscles and senses) + Autonomic nervous system (involuntary muscles - sympathetic: “fight or flight”, parasympathetic: “rest and digest”)

Question 6

Neurons + Gila

Answer 6

Neurons = receive and transmit information,
Gila = serve many varied functions (e.g., insulation, support)

All neurons consist of a cell body.

A collection of cell bodies in PNS = ganglion, in CNS = nucleus.

Question 7

Nucleus

Answer 7

DNA + protein synthesis including neurotransmitters

Question 8

Soma

Answer 8

Cell body + nucleus.

Question 9

Dendrites

Answer 9

Receives signals from other neurons.

Dendrites are bumpy, they have spines which grow and shrink as a result of repeated activations (e.g., through learning).

Question 10

Axon hillock

Answer 10

Very top of the axon.

Common ‘trigger site’ for action potentials.

Although sometimes action potentials may be triggered at the next segment of the axon.

Question 11

Axons

Answer 11

Carries action potentials.

Transmits signals to other neurons.

Question 12

Axon terminals

Answer 12

End of axon.

Ends in the terminal buttons.

Question 13

Terminal buttons

Answer 13

Release neurotransmitters into the synapse.

Question 14

Myelin sheath

Answer 14

Made of glial cells.

Insulates the axon.

Increases speed of action potential propogation.

Question 15

Nodes of ranvier

Answer 15

Gaps in the myelin sheath.

Site of action potential regeneration in myelinated axons.

Question 16

Afferent/Efferent?

Answer 16

Relative term referring to where the axon is going from or to.

The axon is efferent from the pre-synaptic neuron and afferent to the post-synaptic neurons.

Question 17

Synapse

Answer 17

The gap between two (or more) neurons where messages are chemically transmitted.

The nervous system can be seen as a chain of neurons linked together at synapses.

Question 18

Types of Glial cells

Answer 18

Astrocytes (star-shaped) - involved in response to injury of the CNS; regulate blood flow to some neurons.

Oligodendrocytes - form myelin in CNS (Schwann cells form myelin in PNS)

Microglia - involved in immune response in the CNS.

Question 19

Brain anatomy divisions

Answer 19

Hindbrain (rhombencephalon), Midbrain (mesencephalon) + Forebrain (prosencephalon)

Question 20

Hindbrain

Answer 20

Medulla, pons + cerebellum.

Enlarged extension of the spinal cord into the skull.

Controls vital reflexes - breathing, heartrate, vomiting, salivating, coughing, sneezing - through the cranial nerves.

Cranial nerves control sensations from the head, muscle movements of the head and most parasympathetic output to the organs.

Receptors and muscles of the head are connected to the brain via 12 pairs of cranial nerves.

Each cranial nerve originates in a nucleus (cluster of neurons) that integrates sensory information, regulates the motor output, or both.

The nuclei for cranial nerves V to XII are located in the medulla and pons: those for cranial nerves I to IV are in the midbrain and forebrain.

The pons lies anterior to the medulla.

In the pons, axons from each half of the brain cross to the opposite side of the spinal cord, so that the left hemisphere controls the muscles of the right side of the body and vice versa.

The cerebellum is a large hindbrain structure with many deep folds.

It is mainly known for its role in movement and coordination, but also has cognitive functions.

Question 21

Midbrain

Answer 21

Tectum, superior colliculus + inferior colliculus.

Superior colliculus is important for vision.

Inferior colliculus is important for hearing.

Several nuclei and tracts occur in the midbrain - including the substantia nigra.

Question 22

Forebrain

Answer 22

Most prominent part of mammalian brain, consisting of two cerebral hemispheres (left and right). - hemispheres receive sensory input, and control muscles on the opposite side of the body.

Consists of: limbic system, diencephalon, basal ganglia and cerebral cortex.