Lecture 6 + Sample Short Answer

Question 1

Brown-Séquard Syndrome

Answer 1

A rare condition resulting from hemisection of the spinal cord, leading to different sensory and motor system impairments on the affected side.

Question 1

Syringomelia

Answer 1

fluid-filled cyst forms in the spinal cord, leading to neurological symptoms like pain and weakness.

Question 2

You run your right hand over the surface of a pineapple, and wonder about how the perception of its rough, complex surface appears in your mind.

Answer 2

1) When you touch the pineapple, specialized receptors in your skin, like Meissner’s corpuscles or Pacinian corpuscles, detect the texture and send signals through first-order neurons.
2)These signals enter the spinal cord and synapse with second-order neurons in the medulla.
3)These second-order neurons cross over to the opposite side of the brainstem before ascending further. 4) They reach the thalamus, where third-order neurons transmit the information to the somatosensory cortex in your brain for you to perceive the pineapple’s texture.
5) This process occurs through the Dorsal Column-Medial Lemniscal System (DCMLS) pathway, allowing you to sense and understand the pineapple’s surface.

Question 3

In the course so far, we have looked in detail at a number of the Rexed laminae in the grey matter of the spinal cord. We have not yet covered, in much detail, any pathways that travel through laminae VIII-X. Why not?

Answer 3

Laminae VIII-X of the grey matter in the spinal cord are primarily involved in the processing of autonomic functions and motor coordination rather than sensory pathways.

Question 4

What is the main functional difference between two-neuron reflex arcs and three-neuron reflex arcs?

Answer 4

Two-neuron reflex arcs involve just two neurons (sensory and motor) and are simple, rapid responses to sensory input, like the knee-jerk reflex. Three-neuron reflex arcs involve three neurons (sensory, interneuron, and motor) and are more complex, allowing for processing and coordination of motor responses, like withdrawal reflexes or those requiring fine motor control.

Question 5

What two main structures make up the prosencephalon?

Answer 5

the telencephalon and the diencephalon

Question 6

Why are they grouped together under the single name prosencephalon or forebrain?

Answer 6

They are grouped together under the single name “prosencephalon” because they both play crucial roles in higher-order brain functions, including complex sensory processing, motor control, and cognition.
1) The telencephalon, which includes the cerebral cortex, is responsible for advanced cognitive functions, 2) while the diencephalon, with structures like the thalamus and hypothalamus, is essential for relaying sensory information and regulating various bodily functions.

Question 7

What makes a molecule a neurotransmitter or a neurohormone?

Answer 7

1) Neurotransmitters facilitate local and rapid communication between nerve cells at synapses, effects are short-lived
2) Neurohormones, released into the bloodstream, act systemically and affect distant target cells or organs, regulating functions like metabolism and stress responses, effects are more prolonged