mt training: endocrine

3. Adrenocorticotropic hormone (ACTH)—This hormone stimulates the growth of the adrenal cortex and increases its secretion of steroid hormones (primarily cortisol).

4. Gonadotropic hormones — There are several gonadotropic hormones that influence the growth and hormone secretion of the ovaries in females and testes in males.

In the female, follicle-stimulating hormones (FSH) and luteinzing hormone (LH) stimulate the growth of eggs in the ovaries, production of hormones, and ovulation.

In male, FSH influences the production of sperm and LH (as interstitial cell-stimulating hormone) stimulates the testes to produce testesterone.

5. Prolactin (PRL)—This hormone stimulates and sustains milk production after birth.

6. Melanocyte-stimulating hormone (MSH)—This hormone influence the formation of melanin and causes increased pigmentation of the skin. This effect is observed only when hypersecretion of the hormone occurs.

The posterior pituitary gland secretes two important hormones.

(These hormones are formed in the hypothalamus but secreted through the posterior pituitary gland.)

1. Antidiuretic hormone (ADH) --- This hormone, also known as vasopressin, stimulates the reabsorption of water by the kidney tubules. In addition, ADH can also increase blood pressure by constricting arterioles.

2. Oxytocin ---This hormone stimulates the uterus to contract during childbirth and maintains labor during childbirth. Oxytocin is also secreted during suckling and causes the production of milk from the mammary glands.

Table 1-2. MAJOR ENDOCRINE GLANDS, THE HORMONES THEY PRODUCE, AND ACTIONS

Endocrine Gland

Hormone

Action

Thyroid

Thyroxine, triiodothyronine

Increases metabolism in body cells

Parathyroids

Calcitonin

Parathyroid hormone

Lowers blood calcium

Increases blood calcium

Adrenal Cortex

Aldosterone (mineralocorticoid)

Cortisol (glucocorticoid)

Androgens, estrogens and

Progestins

Increase reabsorption of sodium

increases blood sugar

maintains secondary sex

characteristics.

Adrenal Medulla

Epinephrine (adrenaline)

Norepinephrine (noradrenaline)

sympathomimetic (raises BP and heart rate and dilates airways)

Sympathomimetic

Pancreas

Islet cells

Insulin

Glucagon

Decreases blood sugar (glucose to glycogen).

Increases blood sugar (glycogen to glucose).

Pituitary

Growth hormone

Thyroid-stimulating

Hormone

Adrenocorticotropic

hormone (ACTH)

Increases bone and tissue growth

Stimulated production of thyroxine

and growth of the thyroid gland

stimulates secretion of hormones

from the adrenal cortex

Anterior lobe

Gonadotropins

Follicle-stimulating

hormone (FSH)

Luteinizing hormone(LH);

Prolactin (PRL)

Melanocyte-stimulating

Hormone (MSH)

Oogenesis and spermatogenesis

Promotes ovulation (in females)

testesterone secretion (in males)

promotes growth of breast tissue

and milk secretion

Increases pigmentation of the skin

Posterior lobe

Antidiuretic hormone

(ADH; vasopression)

Oxytocin

Stimulates reabsorption of

by kidney tubules

stimulates contraction of the

uterus during labor & childbirth

Ovaries

Estradiol

Progesterone

Develops and maintains

secondary sex characteristics in the female

Prepares ;and maintains the

Uterus in pregnancy.

Testes

Testosterone

Promotes growth and maintenance of secondary sex characteristics in the male.

6. Ovaries

The ovaries are two small glands located in the lower abdominal region of the female. The ovaries produce the female gamete, the ovum, as well as hormones that are responsible for female sex characteristics and regulation of the menstrual cycle.

The ovarian hormones are estradiol (an estrogen) and progesterone. Estradiol is responsible for the development and maintenance of secondary sex characteristics, such as hair and breast development. Progesterone is responsible for the preparation and maintenance of the uterus in pregnancy.