Endocrine Glands

Endocrine Glands

HypothalamusThis organ is a part of the midbrain, and

it is located below the thalamus.

It has various functions including:regulating the ANS,

influencing emotions, and feelings ofhunger, thirst, and body temperature.

Many hormones related to the hypothalamus are considered “releasing hormones”

These releasing hormones are made in the hypothalamus and are released from the

posterior pituitary.

EX: Antidiuretic hormone (vaspressin) and oxytocin.

Other hypothalamic hormones target the anterior pituitary.

The Pituitary

This organ is located in the brain, suspended from the hypothalamus by a stalk called the infundibulum and located in a recess called

the stella turnica (Turk’s saddle).

It is known as the master gland, and it is also known as the hypophysis.

It has two portions – anterior and posterior.

Anterior Pituitary

This organ is located in the brain and is also known as the adenohypophysis.

It is largely regulated by the “releasing” hormones from the hypothalamus.

Anterior Pituitary

Hormones released by the AP include:

1. TSH (thryoid stimulating hormone/thyrotropin)

2. ACTH (adrenocorticotropic hormone)

3. FSH (follicle stimulating hormone)

Anterior Pituitary

Hormones released by the AP include:

4. LH (lutenizing hormone)

5. GH (growth hormone)

6. Prolactin (releasing hormone)

Anterior Pituitary Disorder Example

Growth hormone normally promotes:mitosis and the growth (elongation) of

long bones

A homeostatic imbalance can have serious, life-changing effects.

The hormonal imbalance has various effects that are dependent on when

the imbalance occurs.

In adulthood, too much (hypersecretion) GH results in

acromegaly.

The mandible, feet, and hands enlarge.

http://knightsbridge.net/

In childhood, hypersecretion results in giantism – a large proportional

individual.

In childhood, an insufficient amount (hyposecretion) results in pituitary

dwarfism.

Posterior PituitaryThis organ is located in the brain and is

also known as the neurohypophysis.

It is a storage and a release site for oxytocin and antidiurectic hormone

from the hypothalamus

Oxytocin and ADH are made in the hypothalamus and released by the

posterior pituitary.

Oxytocin - stimulates smooth muscle contraction of uterus & mammary

glands.

ADH - stimulates water reabsorption in collecting ducts and vasoconstriction

People with diabetes insipidus lack ADH

Posterior Pituitary Disorder Example

Hyposecretion of ADH will resultin diabetes insipidus which is

characterized by excessive thirst andurination.

The PinealThis organ is located in the brain toward

the base of the corpus callosum.

This organ has been described as a “lump of tissue in the brain that is light

sensitive”.

It secretes melatonin to the blood and CSF during the night (dark).

MelatoninInfluences the sleep/wake cycle and helps

set the body’s clock

Also influence reproductive organs – it isthought to inhibit early puberty.

Melatonin is high when we are young and is reduced as we age.

MelatoninBecause it influences the sleep/wake cycle,

melatonin plays a role in jet lag.

Because it is secreted in the dark, melatonin plays a role in seasonal affective disorder

(SAD) that is seen in the winter.

Depression often brings on the desire to sleep – made worse when taking

melatonin.