▶️ Answer/Explanation
Swallowing is controlled by both voluntary and involuntary neural mechanisms.
Initiation (Voluntary Phase):
Swallowing begins voluntarily when the cerebral cortex (specifically the motor cortex) sends signals to the muscles of the mouth and tongue to push the bolus of food toward the back of the throat.
Reflex Phase (Involuntary):
As the bolus reaches the pharynx, stretch receptors are activated.
This triggers an autonomic reflex coordinated by the swallowing center in the medulla oblongata (part of the brainstem).
Muscle Coordination:
The medulla sends impulses through cranial nerves (especially glossopharyngeal and vagus nerves) to the muscles of the pharynx, larynx, and esophagus.
These muscles contract in a precise sequence to close the airway (epiglottis blocks the trachea), open the esophagus, and push the bolus downward.
Final Phase (Esophageal):
The bolus is moved down the esophagus by peristaltic contractions, also regulated by the autonomic nervous system.
Markscheme:
a. «usually» autonomic reflex
b. «usually» involuntary/automatic
OR
not controlled consciously
c. coordinated by medulla «oblongata»
d. can be voluntary/consciously controlled «by cerebral cortex»
▶️ Answer/Explanation
a.
- fMRI allows imaging through magnetic resonance.
- It measures blood flow, which correlates with neural activity, enabling the identification of active brain regions.
- The method is non-invasive, providing a safe and real-time way to observe brain activity.
- Allows researchers to detect subtle differences in activation across conditions (e.g., THC, placebo, CBD).
b.
- Parahippocampus:
- THC causes a negative/inhibitory mean activation.
- CBD causes a positive/excitatory mean activation.
- Placebo shows a small positive activation, less than CBD.
- Thus, THC and CBD have opposite effects on parahippocampal activation.
- Visual cortex:
- Both THC and CBD cause positive/excitatory activation.
- The activation from CBD is stronger than both THC and placebo.
- THC shows the lowest activation of the three in both regions.
- In both brain areas, the activation is greater for CBD compared to THC.
- Overall magnitude:
- Activation effects in the visual cortex are larger than in the parahippocampus for all treatments.
c.
- The visual cortex is responsible for processing visual information received from the optic nerve.
It interprets features like shape, color, motion, and depth, allowing visual perception.
Markscheme:
a.
- fMRI allows imaging through magnetic resonance
- To measure the amount of activity/blood flow in different parts of the brain OR to identify the parts of the brain that are activated
- Non-invasive/indirect observation/real time observation
b.
- THC causes a negative/inhibitory mean activation of parahippocampus whereas CBD causes a positive/excitatory one OR THC and CBD cause opposite effects on parahippocampus
- Both cause a positive/excitatory mean activation of the visual cortex
- Magnitude of mean activation of both ingredients is minute on parahippocampus compared to visual cortex (OWTTE)
- Mean activation due to THC lower than CBD for both parahippocampus and visual cortex OR mean activation due to THC lower than placebo whereas higher for CBD for both
- Other valid comparison/contrast between the two drugs
c.
- Processing visual information/signals from the optic nerve (OWTTE)
▶️ Answer/Explanation
a.i.
The cerebellum helps in controlling movement and maintaining balance.
b.
One hormone-producing structure is the pituitary gland, which can be labeled just below the brain, near the middle.
Alternatively, you can label the hypothalamus, just above the pituitary.
c.
One method is fMRI (functional magnetic resonance imaging). It shows which parts of the brain are active by measuring blood flow.
The cerebellum helps in controlling movement and maintaining balance.
b.
One hormone-producing structure is the pituitary gland, which can be labeled just below the brain, near the middle.
Alternatively, you can label the hypothalamus, just above the pituitary.
c.
One method is fMRI (functional magnetic resonance imaging). It shows which parts of the brain are active by measuring blood flow.
Another is during brain surgery, doctors sometimes use electrical stimulation to see how different areas affect behavior.
Markscheme:
a.i.
Label to cerebellum:
a.ii.
• Controls/coordinates (motor) movements
• Maintains balance
b.
• Label to pituitary gland
OR
• Label to hypothalamus
c.
Alternative 1:
• fMRI (functional magnetic resonance imaging)
• Scan detects changes in blood flow/oxygenation in blood
OR
• More active parts of brain receive increased blood flow
Alternative 2:
• Lesion studies/autopsy
• Examination of damaged brain areas
OR
• Correlation of damage location with functional loss
Alternative 3:
• Electrical stimulation during neurosurgery
• Observation of behavioral/physiological responses
Note: Description must relate to the specific method named. For fMRI, the “f” must be written as “fMRI”.