Glossary H

Hippocampus

A part of the brain, located in the medial temporal lobe. It belongs to the limbic system and plays major roles in short term memory and spatial navigation. Humans and other mammals have two hippocampi, one in each side of the brain.

Hormone

A chemical substance produced in the body which has a specific effect on the activity of certain cells or a certain organ or organs.

HPA axis

See Hypothalamic-Pituitary-Adrenal axis (HPA axis).

Hyper

A prefix signifying above, beyond, or excessive.

Hyperalgesia

A greater-than-normal sensitivity to pain.

Hyperirritability

Over-the-top responsiveness to slight stimuli.

Hypertension

High blood pressure.

Hypo

A prefix signifying beneath, under, or deficient.

Hypotension

Low blood pressure.

Hypothalamic-Pituitary-Adrenal axis (HPA axis)

Also known as the limbic-hypothalamic-pituitary-adrenal axis (LHPA axis). A complex set of direct influences and feedback interactions between the hypothalamus, the pituitary gland, and the adrenal or suprarenal gland. The interactions between these three organs constitute the HPA axis, a major part of the neuroendocrine system controlling reactions to stress and regulating various body processes.

Hypothalamus

The part of the brain lying below the thalamus, that regulates bodily temperature, certain metabolic processes, and other autonomic activities.