Lab 2: Brain Anatomy and Neurophysiology

Question 1

bilateral internal carotid arteries enter the brain:

Answer 1

carotid canals

Question 2

Vertebral arteries enter the brain:

Answer 2

foramen magnum (base of skull)

Question 3

why is the circle of willis critical for brain blood flow? What does the term anastomoses mean?

Answer 3

its where the internal carotid artery and vertebral artery connect so that blood can flow. Provides blood supply to the brain. Anastomoses means a natural or surgical connection between 2 structures.

Question 4

A stroke occurs when blood flow to the brain is obstructed, often by a clot or arterial blockage, depriving neural tissue of oxygen and nutrients - cells can die within minutes. Are all blockages the same? Blockage types:

Answer 4

All blockages are not the same. Blockages are redundant, there are other ways to get blood. Blockage types:
1. Stationary blockage (thrombosis)
2. Floating blockage (embolism)
3. Hemorrhage/rupture of blood vessel

Question 5

Symptoms of a stroke can be very different. Why so? What is lateralization?

Answer 5

different brain areas are affected (no blood flow). Diff areas control diff abilities.

Question 6

Will all nutrients cross from the systemic circulatory system into the brain?

Answer 6

No, most proteins can’t cross cause of large size and hydrophilicity. Water soluble molecules can pass (membrane is lipid based). Toxins can’t pass.

Question 7

Glucose, a carbohydrate macromolecule, and oxygen are permitted to pass easily through the blood brain barrier. Why is this important? Why does this happen?

Answer 7

Body needs glucose and oxygen for ATP. Carrier-mediated transport enables molecules with low lipid solubility to cross . Glucose enters by transport protein. Glucose is the brain’s primary energy.
Transcellular transport is what allows oxygen to enter the brain.

Question 8

The blood brain barrier can become damaged from trauma or aging - what would you suspect might happen next?

Answer 8

Barrier becomes more porous, allowing bacteria and other toxins to infect brain tissue. Leads to inflammation and death. Accumulation of toxins, inflammatory cells in neural tissue.

Question 9

You are a scientist who made a medication to cure alzheimer’s. Does Blood brain barrier positively or negatively impact delivery of medication?

Answer 9

negatively, makes it difficult to diffuse/let antibiotics pass. will deem them a foreign substance if its a new antibiotic.

Question 10

longitudinal fissure separates:

Answer 10

2 cerebral hemispheres

Question 11

central sulcus seperates

Answer 11

frontal and parietal lobes

Question 12

lateral sulcus seperates

Answer 12

frontal and temporal lobes

Question 13

precentral gyrus seperates:

Answer 13

anterior to central sulcus, primary sensory area Postcentral gyrus: posterior to central sulcus - primary motor area

Question 14

Why does the brain have folds? Difference between sulci, gyri, fissure?

Answer 14

To inc. surface area. Sulci: shallow depression, Gyri: ridges/peaks, Fissure: deep depressions

Question 15

Where is the central sulcus in relation to precentral gyrus. What is precentral gyrus role?

Answer 15

its anterior to precentral gyrus. Primary motor area - voluntary muscle contractions

Question 16

Where is the central sulcus in relation to postcentral gyrus. Role of postcentral gyrus?

Answer 16

posterior to central sulcus. Primary somatosensory area

Question 17

Pathway of cerebrospinal fluid:

Answer 17

Choroid plexus of (lateral, 3rd and 4th ventricles) -> lateral, 3rd and 4th ventricle -> subarachnoid space -> arachnoid villi of dural venus

Question 18

Major role of CSF

Answer 18

protection, nutrients, shock absorption

Question 19

how can a cerebral hemorrhage progress to an ischemic stroke?

Answer 19

blood accumulates outside vessel. Increase in pressure around vasculature, vessels collapse, no blood flow = stroke

Question 20

what is cerebral atrophy? How can an ischemic stroke lead to cerebral atrophy?

Answer 20

Cerebral atrophy is a loss of brain cells and the connections between them DUring an ischemic stroke there is low blood flow to one part of the brain. No blood flow/nutrients means vessels will die. Atrophy = decrease in brain size.

Question 21

Compare healthy specimen to pathological hemorrhage specimen. What differences can you observe?

Answer 21

general thinning of cerebrum, cerebral cortex, discoloration

Question 22

Function of infundibulum?

Answer 22

connect hypothalamus and pituitary gland

Question 23

primary function of pituitary gland?

Answer 23

hormone regulation and secretion

Question 24

compare the size of olfactory bulbs in sheep with those in humans - what do you see and why?

Answer 24

bigger - sheep rely on sense of smell more (more sensitive)

Question 25

what colour are the olfactory bulbs, in comparison to the surface of the cerebral cortex?

Answer 25

lighter shade - white matter, meaning myelinated

Question 26

what does chiasm mean? what biological function does this nerve layout allow for?

Answer 26

cross/meet. allows optic nerves to cross.

Question 27

midbrain

Answer 27

(Posterior to optic chiasm, situated superior to pons, disappears under the pons) auditory and visual processing, the regulation of the sleep wake cycle, contributing to functions such as eye movement and pain management

Question 28

pons

Answer 28

(A horseshoe shape, opposite to the cerebellum, superior to medulla) Plays a significant role in regulating sleep cycles, processing sensory information, and coordinating facial movements and sensation through cranial nerves

Question 29

Medulla

Answer 29

(Most inferior, stem like structure, base of brain, superficially blends in with the spinal cord) Crucial for autonomic functions such as controlling breathing, heart rate, blood pressure, as well as reflexes like swallowing and coughing

Question 30

together the midbrain, pons and medulla are called the:

Answer 30

brainstem

Question 31

cerebellum function:

Answer 31

coordination and locomotion

Question 32

Folia function:

Answer 32

increases surface area of brain, to accommodate greater number of neuronal cells

Question 33

vermis function:

Answer 33

bodily posture and locomotion

Question 34

pons function:*****

Answer 34

optimizes communication pathways to carry information to and from the cerebellum

Question 35

How is nerve velocity measured (how was experiment done)?

Answer 35

small electrical current applied to our motor neurons and contraction of muscle movement is measured

Question 36

examine the latency period (brief interval between the initiation of an action potential in a motor neuron and the onset of contraction in the muscle fibers) for the median nerve at the wrist (abductor pollicis brevis) and the median nerve at the elbow. How do those latencies differ and why do you suppose that is?

Answer 36

the AP travels further from the median elbow, more latency so less twitch

Question 37

What are the three phases of muscle twitch contraction?

Answer 37

1. Initial/latency 2.contraction 3 relaxation