Hypothalamus

ENDOCRINE SYSTEM

DEFINITION

Ductless gland Exerts chemical control over the human

body Maintains homeostasis Acts with nervous system to coordinate

the body's activities

Uses chemical messengers called hormones that are transported by the circulatory system (blood)

HORMONES

AMINO ACIDS- simplest form- epinephrine and norepinephrine,

oxytocin and vasopressin

PROTEIN HORMONES – insulin and gonad

STEROID HORMONES- lipids-cortisol, estrogen and testosterone

NEGATIVE FEEDBACK

Chemical control of the body functions

When the concentrations of a particular hormone reaches a certain level in the body, the endocrine gland that secreted that hormone is inhibited (the negative feedback)

The secretion of that hormone decreases significantly

HYPOTHALAMUS

DEFINITION

Inferior part of the diencephalon

*DIENCEPHALON- one of the major parts of the brain containing the thalamus and hypothalamus

Control center of all autonomic regulatory activities of the body

Functions:

Main function is homeostasis*HOMEOSTASIS - maintaining the body’s internal environment

Plays a major role in controlling the secretions from the pituitary gland

* INFUNDIBULUM – connects the floor of the hypothalamus to the pituitary gland

Sends neural and chemical signals to the pituitary gland

CHEMICAL SIGNALS

1. Releasing Hormones Main purpose is to control the release of

another hormone Stimulates the release of hormones Capillary bed, portal vein, receptors

2. Inhibitory Hormones Inhibits release of hormones from

another structure convey the hormones through the

pituitary stalk into the anterior pituitary

RELEASING HORMONES

Thyrotropin-releasing hormone

 Stimulates the secretion of thyroid-stimulating hormone from the pituitary

Secretion of another pituitary hormone called prolactin

Involved in the control of body temperature

RELEASING HORMONES

Gonadotropin-releasing hormone

Stimulates the synthesis and release of the two pituitary gonadotropins

oLuteinizing hormone (LH) o Follicle-stimulating hormone (FSH)

Stimulates ovulation in the female ovary

Stimulates synthesis of testosterone to maintain sperm cell production

RELEASING HORMONES

Adrenocorticotropic hormoneStimulates the adrenal cortex to secrete the hormone, cortisol

Growth hormone-releasing hormoneStimulates cell metabolism in most tissues of the body causing cells to divide and increase in size

Stimulates growth of bones and muscles

RELEASING HORMONES

Oxytocin Contraction of smooth muscles

in the wall of the uterus

Vasopressin Controls the reabsorption of molecules in the tubules of the kidneys by affecting the tissue's permeability

INHIBITING HORMONES

Growth hormone inhibiting hormone (GIH)

Also known as Somatostatin

Prolactin release inhibiting hormone (PIH)

also known as Dopamine