Central Control - Hypothalamus

Infundibulum

Stalk connecting the hypothalamus to the pituitary gland.

Lateral Zone

Hypothalamic zone involved in behaviours such as feeding and sleep.

Periventricular Zone

Contains neurosecretory cells that secrete hormones and regulate autonomic function.

Hypothalamus General Function

Integrates internal and external cues to coordinate homeostasis.

Posterior Pituitary Communication

Magnocellular neurons project axons down the hypothalamic-hypophyseal tract.

Posterior Pituitary Hormone Source

Hormones are made in the hypothalamus and released from the posterior pituitary.

Anterior Pituitary Communication

Parvocellular neurons release hormones into the hypophysial portal system.

TRH

Stimulates TSH release, leading to thyroid hormone production.

CRH

Stimulates ACTH release, leading to cortisol production from the adrenal cortex.

GnRH

Stimulates the anterior pituitary to release LH and FSH.

Growth Hormone Regulation

stimulating GHRH and inhibiting GHIH.

Prolactin Regulation

inhibition by prolactin-inhibiting hormone.

Oxytocin Functions

Stimulates uterine contractions and milk ejection from mammary glands.

Vasopressin (ADH) Function

Acts on kidneys to increase water reabsorption and blood volume.

Lipostatic Theory

The body attempts to maintain relatively stable fat and energy stores.

Ghrelin Source and Effect

Produced by an empty stomach to increase hunger.

Leptin Source and Effect

Produced by adipocytes to signal sufficient energy and reduce hunger.

Arcuate Nucleus (ARC) Role

Integrates hormonal hunger and satiety signals.

Lateral Hypothalamic Area (LHA)

Promotes feeding and hunger.

Paraventricular Nucleus (PVN)

Promotes satiety and stops eating.

NPY/AgRP Neurons

Hunger neurons activated by ghrelin in the arcuate nucleus.

alpha-MSH/CART Neurons

Satiety neurons activated by leptin in the arcuate nucleus.

Posterior Pituitary cells

Magnocellular

Anterior Pituitary cells

Parvocellular

hormone signals (speed/time)

slower and more sustained

Inhibitory Hormones

GHIH & PIH

Releasing Hormones

TRH, CRH, GnRH, GHRH