Endocrinology... The Study of Hormones

Today's Warm-up: Name one thing you think hormones are responsible for doing in your body.

Let’s Start With Some Vocab…

Hormone - substance produced by one gland or organ of the body that then travels through the bloodstream to affect other tissues, organs, etc.

Gland – Specialized group of cells that releases hormones into the bloodstream.

Organ - collection of tissues joined in structural unit to serve a common function.

How Hormonal Feedback Works

1) Based on feedback from the body, the first endocrine gland initiates release of a hormone.

2) The first hormone travels through the bloodstream to a second (target) gland.

3) The second gland releases a second hormone, which travels through the bloodstream to a target organ.

4) The target organ has a specific response to the hormone, and performs some biological function.

5) The hormone products from the second gland and the target organ travel through the bloodstream to provide feedback to the first and second endocrine glands.

Makes

Act

s O

n

Makes

Acts On

Acts On

Mak

es

Hormone #1i.e. GHRH

Hormone #2 i.e. GH

Hor

mon

e #3

i.e

. IG

F-I

Tissues i.e. growth of muscle and bone.

Hormones Make All of Our Bodily Functions Possible

Growth Hormones Thyroid Hormones Sex Hormones Stress Hormones Pancreatic Hormones Pregnancy Hormones

Endocrine Glands

Make a Chart to Keep Track…

In one column, put the “Hormone Name” In the 2nd column, put the “Hormone Source” In the 3rd column, put the “Hormone Target” In the 4th column, put the “Hormone Function”

Stress Hormones

Key hormones: CRH (Corticotrophin Releasing Hormone)

Source: Hypothalamus Target: Anterior Pituitary Gland Function: Causes the release of ACTH from the Anterior Pituitary

gland ACTH (Adrenocorticotropin)

Source: Anterior Pituitary gland Target: Adrenal Gland Function: Causes the release of Cortisol from the Adrenal gland

Cortisol Source: Adrenal Gland Target: Systemic tissues Function: “Fight-type” responses

Stress Hormone Cascade

Growth Hormones GHRH-Growth Hormone Releasing Hormone and SS -

Somatostatin Source: Hypothalamus Target: Anterior Pituitary Gland Function: Stimulate release of GH from Anterior Pituitary

GH – Growth Hormone Source: Anterior Pituitary gland Target: Liver Function: Stimulates release of IGF-I from the liver

IGF-I Source: Liver Target: Bone, muscle, connective tissues Function: Stimulates growth in tissues

Growth Hormone Axis

Male Sex Hormones• GnRH – Gonadotropin-Releasing

Hormone– Source: Hypothalamus– Target: Anterior Pituitary Gland– Function: Stimulates the release of

LH and FSH from the Anterior Pituitary

• LH – Luteinizing Hormone– Source: Anterior Pituitary Gland – Target: Leydig Cells of Testicle– Function: Stimulates Testosterone

production

• FSH – Follicle-Stimulating Hormone– Source: Anterior Pituitary Gland – Target: Sertoli Cells of Testicle– Function: Stimulates sperm

production by the testis

• Inhibin– Source: Testicles (Sertoli Cells) – Target: Negative Feedback on FSH

production– Function: Regulate spermatogenesis

• Testosterone– Source: Testicles (Leydig Cells)– Target: Hypothalamus, Anterior

Pituitary, Systemic Tissues– Function: Negative feedback on LH

production, male sex characteristics

Male Sex Hormone Axis

Hormones and Spermatogenesis

The dreaded female hormones...

Female Sex Hormones• GnRH – Gonadotropin-Releasing

Hormone– Source: Hypothalamus– Target: Anterior Pituitary Gland– Function: Stimulates the release of

LH and FSH from the Anterior Pituitary

• LH – Luteinizing Hormone– Source: Anterior Pituitary Gland – Target: Ovary (Thecal Cells)– Function: Stimulates Estrogen

production• FSH – Follicle-Stimulating

Hormone– Source: Anterior Pituitary Gland – Target: Follicle (Granulosa cells) of

Ovary– Function: Stimulates oogenesis

• Inhibin– Source: Ovary (Granulosa Cell)– Target: Negative Feedback on FSH

production– Function: Regulate oogenesis

Progesterone– Source: Granulosa Cell (CL)– Target: Anterior Pituitary Gland,

Hypothalamus– Function: Negative feedback on

hypothalamus and anterior pituitary• Estrogen

– Source: Ovary (Theca and Granulosa Cells)

– Target: Hypothaltmus, Anterior Pituitary, Systemic Tissues

– Function: Negative feedback on hypothalamus and anterior pituitary, female sex characteristics

Feedback of Female Sex Hormones

Female Reproductive Hormones

Thyroid Hormones

• TRH – Thyroid Releasing Hormone– Source: Hypothalamus– Target: Anterior Pituitary– Function:Stimulates the release of

TSH from the Anterior Pituitary gland

• TSH – Thyroid Stimulating Hormone– Source: Anterior Pituitary Gland– Target: Thyroid Gland– Function: Stimulates the release of

T3 and T4 from the Thyroid.

• T3 – Triiodothyronine (10%)– Source: Thyroid Gland– Target: Systemic Tissues– Function: Metabolism, heart rate,

growth, brain development and function

• T4 – Thyroxine Hormone (90%)– Source: Thyroid Gland– Target: Systemic Tissues– Function: Metabolism, heart rate,

growth, brain development and function

• Calcitonin– Source: Thyroid Gland– Target: Bone and kidneys– Function: Bone regeneration, urine

production in the kidney

Thyroid Hormones

Neuroendocrine feedback : the Breastfeeding

Response

Pancreatic Hormones

Normal Pancreatic Hormones

Diabetes

Other Hormones of Note...

• Oxytocin– Source: Posterior Pituitary– Target: Uterus, breasts– Function: Uterine contractions and

milk let-down

• Melatonin– Source: Pineal Gland– Target: Bodily tissues– Function: Sexual maturity and body

rhythms

• ANF (Atrial Naturietic Factor)– Source: Heart– Target: Kidney– Function: Regulates blood pressure

• Renin– Source: Kidney– Target: Adrenal Gland– Function: Regulates blood pressure

through regulation of aldosterone secretion.

• Erythropoiten– Source: Kidney– Target: Bone Marrow– Function: Red blood cell production

• Aldosterone– Source: Adrenal Gland– Target: Kidney– Function: Regulation of urine

volume and blood pressure

Other Hormones of Note...

• Parathyroid Hormone– Source: Parathyroid

– Target: Plasma

– Function: Regulates plasma calcium and phosphate

• Thymopoiten– Source: Thymus

– Target: White blood cells

– Function: T-Lymphocyte Function