Utsw Endocrine Glands And Their Function

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Hypothalamus

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Part of the Brain: The Control and Relay Center of the Endocrine System and also functions in the CNS.

Causes the release of adrenaline through the CNS during flight and fight.

As an endocrine organ, its primary hormones are Oxytocin and ADH.

Though it creates ADH (vassopressin) and Oxytocin; doesn't store it.

It secretes "regulatory hormones" (special hormones that regulate the activieties of the anterior pituitary gland) directly into the circulation. Those hormones are RH (releasing hormones and IH (inhibiting hormones).

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Pituitary or hypophysis

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Pituitary or hypophysis is located at the center of the base of the brain and rests in a small, bony cavity called sella turcica .
Known as the "Master Gland", this part of the brain consists of three lobes called anterior, interior, and posterior pituitary.

Follicle-stimulating hormone (FSH) is a hormone synthesized and secreted by gonadotropes in the anterior pituitary gland. FSH regulates the development, growth, pubertal maturation, and reproductive processes of the human body. FSH and Luteinizing hormone (LH) act synergistically in reproduction.

Luteinizing hormone (LH, also known as lutropin[1]) is a hormone produced by the anterior pituitary gland.

In the female, an acute rise of LH – the LH surge – triggers ovulation. [2]
In the male, where LH had also been called Interstitial Cell Stimulating Hormone (ICSH),[3] it stimulates Leydig cell production of testosterone. [4]

Front 3

Posterior pituitary

Back 3

Posterior pituitary produces
Oxytocin and ADH (anti-diuretic hormone) also known as vasopressin.

Front 4

Oxitocin

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Oxytocin:It is best known for its roles in female reproduction: it is released in large amounts after distension of the cervix and vagina during labor, and after stimulation of the nipples, facilitating birth and breastfeeding, respectively. Recent studies have begun to investigate oxytocin's role in various behaviors, including orgasm, social recognition, pair bonding, anxiety, trust, love, and maternal behaviors.

Stimulates utrine contraction and brest contraction for milk release.

Oxytocin has many other potential effects including orgasm and "feelings" such as trust and risk taking but these are not proven conclusively.

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Anterior Pituitary

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Anterior pituitary produces:

Prolactin (PRL) which stimulates the production of breast milk (works in men too).

Human Growth Hormone (HGH) stimulates growth/ Hypo- Dwarfism/Hyper- Gigantism

Thyroid Stimulating Hormone (TSH) Stimulates the thyroid to release thyroxin.

Adrenocorticotrophic Hormone (ACTH) Stimulates the adrenal cortex to produce: Corticosteroids
- mineral corticoids
- glucocorticoids
- cortisol (natural anti-inflammatory)
- androgens, e.g. acdosterone.

Luteinizing Hormone (LH)Brings about ovulation and maintains the corpus luteum.

Follicle Stimulating Hormone (FSH) Stimulates growth/ development of Graafin follicles (= a mature follicle in the ovary prior to ovulation, containing a large fluid-filled cavity that distends the surface of the ovary) on approx. 28 day cycle.

Melanin Stimulating Hormone (MSH)

Gonadotrophins -
Secondary sexual characteristics.

Interstitial Cell Stimulating Hormone (ICSH) a gonadotropic hormone that is secreted by the anterior pituitary; stimulates ovulation in female mammals and stimulates androgen release in male mammals. Works on the seminiferous tubules in the testes – to produce sperm – which take 21 days to mature.
(If not ejaculated within 21 days, the sperm are re-absorbed back into the body.)

Front 6

Intermediate pituitary

Back 6

Intermediate

Control of melanocyte production.

Front 7

The pineal gland (also called the pineal body, epiphysis cerebri, epiphysis or the "third eye")

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A pea-sized mass of nerve tissue attached by a stalk to the posterior wall of the third ventricle of the brain, deep between the cerebral hemispheres at the back of the skull.
(It functions as a gland, secreting the hormone melatonin - which regulates the pituitary gland and is associated with the biological clock.)

Front 8

Melatonin

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Melatonin -
A hormone produced by the pineal gland in darkness but not in bright light.

Melatonin receptors in the brain react to this hormone and synchronize the body to the 24 hour day/night rhythm, thus informing the brain when it is day and when it is night.

Melatonin is derived from seratonin, with which it works to regulate the sleep cycle.

Front 9

Thyroid Gland

Back 9

Your thyroid gland is a small gland, normally weighing less than one ounce, located in the front of the neck. It is made up of two halves, called lobes, that lie along the windpipe (trachea) and are joined together by a narrow band of thyroid tissue, known as the isthmus.


The thyroid is situated just below your "Adams apple" or larynx.

The function of the thyroid gland is to take iodine, found in many foods, and convert it into thyroid hormones: thyroxine (T4) and triiodothyronine (T3). Thyroid cells are the only cells in the body which can absorb iodine. These cells combine iodine and the amino acid tyrosine to make T3 and T4. T3 and T4 are then released into the blood stream and are transported throughout the body where they control metabolism (conversion of oxygen and calories to energy). Every cell in the body depends upon thyroid hormones for regulation of their metabolism. The normal thyroid gland produces about 80% T4 and about 20% T3, however, T3 possesses about four times the hormone "strength" as T4.

The thyroid gland is under the control of the pituitary gland, a small gland the size of a peanut at the base of the brain. When the level of thyroid hormones (T3 & T4) drops too low, the pituitary gland produces Thyroid Stimulating Hormone (TSH) which stimulates the thyroid gland to produce more hormones. Under the influence of TSH, the thyroid will manufacture and secrete T3 and T4 thereby raising their blood levels. The pituitary senses this and responds by decreasing its TSH production. One can imagine the thyroid gland as a furnace and the pituitary gland as the thermostat. Thyroid hormones are like heat. When the heat gets back to the thermostat, it turns the thermostat off. As the room cools (the thyroid hormone levels drop), the thermostat turns back on (TSH increases) and the furnace produces more heat (thyroid hormones).

The pituitary gland itself is regulated by another gland, known as the hypothalamus. The hypothalamus is part of the brain and produces TSH Releasing Hormone (TRH) which tells the pituitary gland to stimulate the thyroid gland (release TSH). One might imagine the hypothalamus as the person who regulates the thermostat since it tells the pituitary gland at what level the thyroid should be set.

Front 10

Calcitonin (also known as "thyrocalcitonin")

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Calcitonin
Uptake of calcium to bone.

(also known as "thyrocalcitonin") is a hormone produced by and secreted from the thyroid gland.



Calcitonin helps to regulate the levels of calcium and phosphate in the blood.
It decreases the amount of calcium in the blood by inhibiting the action of osteoclasts (cells that break down the bone matrix). Hence, calcitonin promotes the movement of calcium ions Ca(2+) into the bone matrix, simultaneously decreasing the quantity of calcium ions Ca(2+) in the blood.

Calcitonin may be given by injection as part of the treatment of hypercalcaemia and Paget's disease (a bone disease).

Front 11

Parathyroid Gland

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Parathyroid Gland is part of the Thyroid/Parathyroid Gland, which is in the neck.

It produces parathormone which is ssociated with the growth of muscle and bone and is responsible for the Distribution of calcium and phosphate in the body.

Hyper- Causes transfer of calcium from the bones to the blood; bones become fragile & easily broken; osteoporosis.
(Parathormone activity is inhibited by oestrogen.)

Hypo- Lowers blood calcium levels, causing tetany (which may be treated by injections of the hormone); low calcium levels in skeletal muscle (which may cause cramps).

Front 12

Thymus

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The thymus gland is located straddled across the trachea & bronchi in the upper thorax (a bi-lobed organ in the root of the neck, above and in front of the heart).
The thymus (a gland associated with the immune system), is enclosed in a capsule and divided internally by cross-walls into many lobules (full of T-lymphocytes). In relation to body size the thymus is largest at birth. It doubles in size by puberty, after which it gradually shrinks, its functional tissue being replaced by fatty tissue. In infancy the thymus controls the development of lymphoid tissue and the immune response to microbes and foreign proteins (accounting for allergic response, antoimmunity, and the rejection of organ transplants). T-lymphocytes migrate from the bone marrow to the thymus, where they mature and differentiate until activated by antigen.

The Thymus produces Thymosin which activates the immune system by activating the T-Cells (T-Killer Cells; T-Helper Cells; T-Memory Cells) and T-Lymphocytes. The thymus consists of lobules full of T-lymphocytes (white blood cells associated with antibody production).

T-lymphocytes migrate from the bone marrow to the thymus, where they mature and differentiate until activated by antigens.

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Pancreas

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The pancreas lies behind the stomach. It is both exocrine (ducted) and endocrine (ductless).

As an exocrine gland it secrets enzymes (organic catalysts) into the small intestine.

The enzymes are:

Pancreatic amylase (which breaks down polysaccharides, i.e. starch into sugar)

Lipase (which breaks down fats into fatty acids and glycerol)

Proteases (which breaks down protein (polypeptide) into di-peptides).

The islets of Langerhans are within the pancreas.

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Islets of Langerhans

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Islets of Langerhans
Located within the pancreas. Contains groups of both Alpha-and Beta- cells.

Beta Cells:
Insulin - Conversion of glucose to glycogen. Cellular up-take of Glucose.

Conversion of excess glucose to fat.

Hyper-

Hypo- causes Diabetes Mellitus:

Symptoms: Blood glucose levels rise (hyperglycaemia). Glucose is excreted into the urine (glycosuria) - which increases levels of urination, causing dehydration.
As glucose levels in the blood increase, fat and protein are broken-down for energy. Coma and death may follow if the symptoms are not treated.

Alpha Cells: Glucagon -Conversion of glycogen to glucose.

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Adrenal Glands

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Adrenal Glands consists of:
Adrenal Medulla and Adrenal Cortex

Adrenal Medulla produces adrenalin which prepares the body for "fright, fight or flight" and has many effects:

Effects: Action of heart increased. Rate and depth of breathing increased. Metabolic rate increased. Force of muscular contraction improves. Onset of muscular fatigue delayed. Blood supply to the bladder and intestines reduced, their muscular walls relax, the sphincters contract.

Noradrenalin which has similar effects to adrenalin:

Effects include: Constriction of small blood vessels leading to increase in blood pressure. Increased blood flow through the coronary arteries and slowing of heart rate. Increase in rate and depth of breathing.
Relaxation of the smooth muscle in the intestinal walls.


Adrenal Cortex: Corticosteroids produces Glucocorticoids (e.g. cortisol, cortisone, corticosterone), hormones for the utilization of carbohydrate, fat and protein by the body and regulate the following:

Normal response to stress.

Anti-inflammatory effects.

Hypersecretion of cortisol results in Cushings Syndrome.

Mineralocorticoids (e.g. aldosterone)

Regulation of salt and water balance.


Hypersecretion of Alderosterone decreases the potassium in the body (affecting nerve impulse transmission and leading to muscular paralysis).

Front 16

Ovaries

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Ovaries
Produce mature ova. Theoretical potential for 400-450 viable ova.
(Therefore the more and the longer pregnancies a woman has, the later her menopause because there is no ovulation during pregnancy.)

Overies produce Oestrogen - Break-down of the utrine wall and progesterone which builds up and maintains the uterus wall for embedding of fertilized egg and is associated with secondary sexual characteristics, e.g. body hair, breast enlargement, changes in physical body.

Front 17

Testes

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Testes
Located outside the pelvic cavity, the Testes produce Testosterone which is responsible for the development and function of male sex organs.

Secondary sexual characteristics. e.g. body hair, muscle development, voice change.

Front 18

Define Hormone

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Hormones are chemical messengers that are released in one tissue and transported by the bn loodstream to reach target cells in other tissues.

Endicrine System is much like the "postal service" for carrying messages. It takes longer for the message to arrive but the message stays longer.

Front 19

What's the difference between endocrine and exocrine glands?

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Endocrine glands have ducts and exocrine glands don't.

Front 20

Explain how protein and steroid hormones are believed to deliver their effects.

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Protein hormones are the largest group of hormones and cannot pass through the cell wall. Protein hormones bind to very specific receptors on the cell surface. Protein (including peptide and amino acids) are referred to as first messengers because they must bine to an appropriate receptor which triggers the apperarance of a second messanger in the cytoplasm which alters the activity of enzymes in the cell.

The "lipid" derivatives, like steroids are capable of crossing the membrane of the cell and binding to intracelluar receptors and therefore do not require receptors on the cell surface. Once inside the cell, these hormone-receptor complexes directly affect gene activity, metabnolism and protein synthesis from within the nucleus or attached to mitochondria.

Front 21

Define negative and positive feedback.

Back 21

Negative is like a thermostat and heater/ac.

Positive is like cooagulating blood that is healing a wound.

Front 22

How many hormones are "MADE" in the pituitary gland?

Back 22

7

Front 23

How many hormones does the Hypothalamus produce?

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2: ADH and Oxytocin

Front 24

How many hormones does the pituitary gland "release"?

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9

Front 25

What is TSH?

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Thyroid Stimulating Hormone:
Stimulates the release of thyroid hormones from the thyroid gland. They then return to the anterior pituitary and inhibit the release of TSH.

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What is FSH?

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Follicle-stimulating hormone:

Promotes egg development in the ovaries and stimulates the secretion of estrogens. Also promotes sperm production.

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What is LH?

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Luteinizing hormone promotes ovarian secretions of estrogensand progestins to prepare a woman for pregnancy. It alwo induces ovulation (expulsion of an egg) in women. In men, LH stimulates the testes to release androgens, the most important being testosterone.

Front 28

What is PRL?

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Prolactin: stimulates the production of mammary glands to produce milk.

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What is GH?

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Growth Hormone:
Stimulates cell growth and replication by increasing rate of protein production. Plays a part in mobilizing energy reserves by breaking glycogen from the liver into useable glucose.

Front 30

What is MSH?

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Melanocyte-stimulating hormone:

Stimulates melanocytes in the skin to produce melanin.