The Endocrine System

Epically Made By: Morgan DiStasio and Falcon Jakiela

“What is it?” Simply put the Endocrine System can be easily

linked to the Nervous System based upon the similarities (i.e. sending signals through the body).

The effects it has on a horse consists of changes in metabolism, stress, growth, and sexual development.

The Glands There are 9 glands within the Endocrine

System:◦ Hypothalamus◦ Pituitary◦ Thyroid◦ Parathyroid◦ Thymus◦ Pancreas◦ Adrenal◦ Ovaries◦ Testes

The Hypothalamus Gland Location?

◦ At the brain. What does it do/What is it?

◦ Controls autonomic functions.◦ Controls emotions.◦ Controls homeostasis.◦ Regulates sleep and wake cycles as well as the water

and food intake systems.◦ Controls motor functions (i.e. movement)

This gland controls the entire Endocrine System, therefore it can be properly called the “President” of the Endocrine.

The Pituitary Gland Location?

◦ At the base of the horse’s brain. This Gland contains 3 Sections; Anterior, Intermediate and

Posterior. What does it do?/What is it?

◦ The anterior section controls the most: Stimulates thyroid w/ THS (thyroid stimulus hormone). Releases growth hormone for cell reproduction/regeneration

and general body growth (GH). Stimulates milk for nursing mothers using Prolactin (PRL) and

produces Luteinizing hormone (LH) to help release eggs during birth.

It releases Follicle stimulus hormone to effect growth, development, maturing and the reproduction process.

Using Adrenocorticotropic, it activates the adrenal cortex. Within males this gland stimulates Leydig cell production to

cause testosterone.

The Pituitary Gland (Cont.) Next is the intermediate section which controls only one

function:

◦ This section produces Melanocyte stimulus hormones (MSH). MHS works on the skin cells containing black pigment.

The last is the Posterior section:

◦ This section releases the Oxytocin hormone. This hormone is required to assist during labor and birth.

◦ It stimulates the Antidiuretic hormone (ADH) release to regulate water balance and causes and increase in absorption of water into the blood by the kidneys.

The Pituitary Gland (Cont.) The entire Pituitary Gland is known as the ‘Master Gland’

and for a good reason, seeing as it controls the rest of the Endocrine System as does the Hypothalamus Gland. But this gland is more like the CEO rather than a president, it simply directs and sends out messages.

The Thyroid Gland Location?

◦ Around the larynx, consisting of two lobes on either side of the windpipe.

What does it do?/What is it?◦ This gland is a regulator more than anything:

It regulates metabolism using a hormone Triiodothyronine (T3).

It regulates the manner by which tissues utilize food for the production of energy and to expand that throughout the body.

The Thyroid Gland (Cont.) Also, it uses a chemical called Thyroxine (T4) which

regulates oxygen levels/oxygen consumption of tissue in the body.

Using Calcitonin, this gland regulates the phosphate metabolism within the horses bones and also assists in regulating the blood calcium levels.

Regulates hormonal levels.◦ Problems producing any of those hormones can effect bodily

functions (i.e. chronic fatigue, muscle weakening, ect).

The Parathyroid Gland Location?

◦ Near the thyroid. Horses are believed to have 4, 2 of which are connected or close to the Thyroid whereas the other 2 would be in the chest but it varies.

What does it do?/What is it?◦ It acts dependently of other glands while sensing plasma

calcium levels and making minute-to-minute adjustments. Calcium in the gland helps in clotting, neuromuscular

controls and muscle contraction. It also provides a sort of “building block” for developing

bones and teeth.

The Parathyroid Gland (Cont.)◦ The Parathyroid Hormone (PTH) increases plasma calcium

by stimulating a message to the bones which then tells the kidneys to release the mineral that helps keep calcium in circulation.

◦ The partner of this gland is Vitamin D because it assists in calcium retention and absorption.

◦ This gland rarely malfunctions.◦ This gland is the size of a shirt button.

The Thymus Gland This gland virtually disappears once a horse grows into an adult. Location?

◦ Between the trachea and the heart of a horse; base of neck. What does it do?/What is it?

◦ The gland plays a part in the immune system and is constantly “on the look out” so to speak.

◦ The main function of this gland comes from the processing and maturation of lymphocytes called T-Cells which are white bloods cells that help defend and detect invading viruses, bacteria and so on.

◦ It basically governs cellular immunity, as in, telling other cells if something foreign is coming along.

◦ Although it disappears it still plays some role in immunology.

The Thymus Gland (Cont.)

The Pancreas Gland Location:

◦ In abdominal cavity near small intestine and below kidneys. What does it do/What is it?

◦ This gland is the primary helper in the body’s energy management system, micromanages metabolism, storage and cellular usage of proteins, fats and carbohydrates.

◦ Insulin is the main modulator of glucose for this gland, it acts quickly after food intake to limit the liver’s production of glucose and causes an increase in stored energy which is known as glycogen. This is helpful because in that organ it helps facilitate

increased protein synthesis to convert unnecessary energy into fat for storage in body tissues and also to possibly control the appetite.

◦ This gland also uses Glucagon to help raise blood sugar levels by pulling reserves out of storage when circulating energy supplies begin to decrease.

The Pancreas Gland (Cont.)

The Adrenal Gland

This gland is also known as “The shock organ”. This gland also has multiple parts; The adrenal cortex and the

adrenal medulla. Location?

◦ Near the kidneys. What does it do?/What is it?

◦ A.C.: Is the outer layer derived from genital-tract cells and is

divided into three zone that produce steroid hormones. ◦ A.M.:

Is the interior derived from neurological cells which produces catecholamines, organic compounds that act as hormones in the blood stream as well as a transmitter for the nervous system.

Adrenal Gland (Cont.)◦ This gland helps regulate body salt levels, blood pressure, and blood

volume.

◦ Its glucocorticoids helps to regulate energy, protein, fat and mineral use as well as help to reduce inflammation.

◦ Its gonadocorticoids influences gender-specific behavior in mares and stallions; within stallions it also participates in sperm production.

◦ Catecholamines influence the “fight or flight” response to a threat.

The Ovaries and Testes Glands Location(s)?

◦ Self-explanatory. What do they do?/What are they?

◦ The Ovaries gland is a female reproductive organ, whereas, the Testes gland is a male reproductive organ.

The ProcessStimulus (change in temperature, ect.)

Detection of stimulus

Release of hormone which travels through bloodstream

Arrival of hormone at target cell

Response to stimulus occurs

Disease Found in The Endocrine

Equine Cushing’s Syndrome: This occurs when signals from other glands begin to stop and fail which cause the Pituitary Gland to stimulate overproduction of the steroid hormone cortisol by the adrenal glands. This leads to a domino-effect of over-activity of other endocrine metabolic disturbances which has outcomes of obesity, behavioral changes, weakening in muscles, and also an abnormally long or curly coat which fails to shed.◦ This disease can also be called:

Pituitary Pars Intermedia Dysfunction.

Sites Used http://www.oxymega.com/thyroid_gland.html http://www.equisearch.com/horses_care/health/anatomy/endocrines

ystem_062907/ http://www.agriscience.msu.edu/3000/3180/3184/3184E/3184E.htm http://www.buzzle.com/articles/pituitary-gland-function.html http://www.becomehealthynow.com/article/bodyimmune/961/

Side notes:◦ After doing this I can honestly say my head hurts and

finding pictures of those glands within a horse is really hard to do.

◦ It was also difficult for us to put this into simple terms so we’re sorry if it wasn’t clear enough.