Eating Disorders, Gut-Brain & Brain Death

Contrast the temperaments of Anorexia (AN) and Bulimia (BN).

AN: perfectionism, anxiety, harm-avoidance, and over-control.

BN: sensation seeking, high impulsivity, and switching between over- and under-control.

How do Serotonin and Dopamine relate to ED behaviors?

Serotonin: Restriction reduces tryptophan, which may temporarily lower anxiety in AN patients.

Dopamine: Altered function in the striatum is linked to reward disturbances and decreased food ingestion.

Describe brain area abnormalities in Eating Disorders.

Parietal Lobe: Linked to body image distortion and denial of illness.

Limbic System: Amygdala imbalances relate to anticipatory anxiety.

Insula: Processes taste; in AN, reduced response suggests a failure to recognize food value or malnutrition.

Explain the Gut-Brain-Microbiome (GBM) Axis.

Bottom-Up: Microbes and metabolites influence brain function via neuroimmune pathways.

Top-Down: The ANS modulates gut motility and permeability, reshaping the microbial habitat.

What are the benefits of Short-Chain Fatty Acids (SCFAs)?

Produced from fiber; they maintain intestinal barrier integrity, reduce inflammation, and stimulate satiety.

What happens when fiber is low in the diet?

Microbes "eat" the protective mucus layer of the gut, leading to "leaky gut" and systemic inflammation.

What have Germ-Free (GF) mice taught us?

GF mice have more permeable Blood-Brain Barriers; adding a healthy microbiome restores barrier function.

Define Brain Death vs. Coma vs. PVS.

Brain Death: Irreversible loss of the entire brain and brainstem; zero possibility of recovery.

Coma: Brainstem and some functions remain.

PVS (Vegetative): Brainstem functions (sleep cycles/breathing), but higher cortex is lost.

What is the role of the RAS in brain death?

The Reticular Activating System (RAS) in the brainstem is responsible for arousal. Since brain death requires brainstem destruction, consciousness is physically impossible.

Why is there a "gap" between medical and legal death?

The law requires all functions to stop, but clinically, some brain-dead patients still have a functioning hypothalamus that releases hormones.

Contrast the Dying-Brain vs. Survivalist positions on NDEs.

Dying-Brain: Claims the mind is what the brain does; NDEs are surges in deep brain activity despite a flat surface EEG.

Survivalist: Claims the mind is independent; a flat EEG is proof the brain was "off," making the experience a spiritual glimpse.

Identify the zones and regions of the Hypothalamus.

Regions (front to back): Preoptic → Supraoptic → Tuberal → Mammillary.

Zones: Periventricular, medial, and lateral.

Homeostatic functions: Suprachiasmatic (motor activity rhythm), Ventromedial (feeding), and Dorsomedial (aggression/rage).