Human Biochemistry · HUMAN BODY • HYPOTHALAMUS • ... insulin and growth hormone. ... Steroid...

Human Biochemistry Hormones

Tuesday, April 10, 2012

THE ENDOCRINE SYSTEM


THE ENDOCRINE SYSTEM• The ENDOCRINE SYSTEM = the organ

system that regulates internal environment conditions by secreting hormones into the bloodstream

Hormones play a huge role in maintaining homeostasis!

Hormones control many developmental changes like PUBERTY!

Hormones can have an effect on pretty much ALL the organ systems!


THE ENDOCRINE SYSTEM• HORMONE = chemicals released by one type

of cell (usually a gland) that has an effect on other cells of the body

• GLAND = an organ that secretes hormones and other useful substances

Endocrine hormones are produced in glands and secreted direction into the blood stream – thus, the circulatory system carries them to the various organs of the body!


MAJOR GLANDS OF THE HUMAN BODY

• HYPOTHALAMUS• PITUITARY GLAND• THYROID GLAND• PARATHYROID GLAND• PANCREAS• ADRENAL GLANDS• KIDNEYS• FEMALE OVARY• MALE TESTES


THE ENDOCRINE SYSTEM• Hormones are secreted into the bloodstream,

and can reach ALL the cells of the body, BUT they will only affect specific target cells

Cells each have specific hormone receptors on their cell

membranes or inside the cell.

This means they will only allow SPECIFIC hormone molecules

to attach. The number of receptors on an individual cell may vary. Cells may have receptors for one hormone and not another.


2 Types of Hormones

Protein hormones include insulin and growth hormone. These hormones are chains of amino acids.

Water soluble!

– PROTEIN HORMONES

Steroid hormones are made from cholesterol and include the sex hormones and cortisol.

Fat soluble!

– STEROID HORMONES


Steroid Hormones

1. Steroid hormones diffuse through the cell membrane of a target cell.

2. Inside the cytoplasm, the hormone attaches to its specific receptor.

3. The hormone-receptor complex then moves into the nucleus, where it activates a gene and initiates protein synthesis.Tuesday, April 10, 2012

Protein Hormones

1. Protein hormones attach to a specific receptor site in the target cell membrane.

2. The hormone-receptor complex promotes the formation of cyclic AMP from ATP.

3. Cyclic AMP acts as a secondary messenger, activating enzymes within the cell.Tuesday, April 10, 2012

The Pituitary Gland • The PITUITARY GLAND = a gland at the base

of the brain that secretes more types of hormones than any other endocrine gland!!!!!

The pituitary gland is only the size of a pea!!!!!!

The pituitary gland often called the MASTER GLAND!


The PITUITARY GLAND is divided into two lobes:

- ANTERIOR LOBE

- POSTERIOR LOBE

The PITUITARY GLAND and the HYPOTHALAMUS interact with each other to produce a variety of different

effects on distant body parts.

Pituitary Gland + Hypothalamus =

The Pituitary Gland


THE ENDOCRINE SYSTEMThe PITUITARY GLAND is connected by a stalk to the HYPOTHALAMUS.

The HYPOTHALAMUS is the area of the brain associated with homeostasis.

Here the interaction between the NERVOUS SYSTEM and the ENDOCRINE SYSTEM becomes obvious! The pituitary gland produces and stores hormones. The hypothalamus stimulates

the release of pituitary hormones via nerves.Tuesday, April 10, 2012

THE ENDOCRINE SYSTEMNeurons in the hypothalamus secrete HORMONE-RELEASING FACTORS into small blood vessels that lead to the anterior lobe of the pituitary gland.

The pituitary gland then releases a number of different hormones.


THE ENDOCRINE SYSTEMHYPOTHALAMUS

HORMONE-RELEASING FACTOR

SMALL BLOOD VESSELS

ANTERIOR LOBE OF PITUITARY GLAND

VARIOUS HORMONES ARE RELEASED

HORMONES ACT ON OTHER PARTS OF THE BODY


Additionally, nerve cells in the hypothalamus produce hormones that travel down the bloodstream and are secreted into the blood stream within the posterior lobe of the pituitary and released into the rest of the body.


ANTERIOR LOBE PITUITARY HORMONES

HORMONE TARGET FUNCTIONThyroid-stimulating hormone (TSH)

Thyroid gland -Stimulates the release of thyroxine from thyroid

- thyroxine regulates cell metabolism.

Adrenocorticotropic hormone (ACTH)

Adrenal cortex - Stimulates release of hormones involved in stress responses.

Somatotropin (STH), or growth hormone (GH)

Most cells - Promotes growth

Follicle-stimulating hormone (FSH)

Ovaries, testes - In females, stimulates follicle development in ovaries.

- In males promotes development of sperm in testes.

Luteinizing hormone (LH)

Ovaries, testes -In females, stimulates ovulation and formation of the corpus luteum

- in males, stimulates the production of the sex hormone testosterone

Prolactin (PRL) Mammary glands

Stimulates and maintains milk production in lactating females


POSTERIOR LOBE PITUITARY HORMONES

HORMONE TARGET FUNCTION

Oxytocin Uterus, mammary glands

-Initiates strong contractions- triggers milk release in lactating females

Antidiuretic hormone (ADH)

Kidneys - Increases water reabsorption by the kidneys


WATER BALANCE• Antidiuretic hormone (ADH) = helps to regulate the osmotic

pressure of body fluids by causing the kidneys to increase water reabsorption.

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ADH is released more water is reabsorbed in the kidneys urine produced is more concentrated

ADH is stored and released by the PITUITARY GLAND its release is signalled by the HYPOTHALAMUS


Thyroid Gland Hormones

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T3 Many different cells - Regulates basal metabolic rate & protein synthesis

T4 Thyroxine Many different cells - Regulates basal metabolic rate & protein synthesis


Adrenal Gland Hormones

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HORMONE TARGET FUNCTIONAdrenaline (epinephrine) Heart, liver,

many others- Fight or flight response - Boosts oxygen supply and glucose to the brain and muscles for a range of actions- Suppresses non-emergency bodily processes

Noradrenaline Muscles - Fight or flight response- Prepares skeletal muscles

Aldosterone Kidneys - increases water reabsorption by the kidneys- affects blood pressure


KIDNEYS AND BLOOD PRESSURE• the kidneys also play a role in the maintenance of blood pressure by

adjusting blood volumes.

» the hormone involved in this feedback loop is ALDOSTERONE

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ALDOSTERONE = is produced in the cortex of the adrenal glands and acts on the kidneys by increasing Na+ reabsorption from the distal tubule and collecting duct.


Pancreas Hormones

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Insulin (produced by beta cells)

Liver, muscle and fat tissue cells

- Causes glucose uptake from the blood to be stored in liver and muscle- Stops use of fat as energy source- Decreases blood glucose levels

Glucagon (produced by alpha cells)

- Stimulates the breakdown of glycogen into glucose- Increases blood glucose levels


Sugar Metabolism Regulation

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Sex Hormones

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HORMONE GLAND TARGET FUNCTION

Estrogen Follicle cells of Ovary

Body cells - stimulates ovulation - initiates secondary female characteristics- thickens endometrium

Progesterone Corpus luteum of Ovary

Uterus, cervix - inhibits ovulation-stimulates endometrium- supports pregnancy

Testosterone Testes, adrenal glands

Body cells - increase muscle mass, bone density, strength- male secondary sex characteristics


Who do we look like?

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Menstruation Cycle

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FSH causes estrogen to rise

1LH stimulates the egg release

2Progesterone increases

3Hormone production decreases and menstruation begins

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Oral Contraceptives

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Oral contraceptives (“the birth control pill”) are composed of synthetic progesterone and estrogen

They are similar enough to perform the same function: they inhibit FSH and LH and so inhibit ovulation

Should the Pill be over the counter? Tuesday, April 10, 2012

‘Roid Rage

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Anabolic steroids mimic testosterone and increase protein synthesis and build up cellular tissue

Anabolism = building up


Anabolic Steroids

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☻GOOD☻ ☹BAD☹ Can be used to trigger puberty

Stimulate bone growth and appetite in cancer patients

Increases LDL cholesterol

Increases blood pressure

Causes liver damage

Bad temper

Acne

Decreased sperm count

Increases muscle mass


Try it!

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Human Biochemistry · HUMAN BODY • HYPOTHALAMUS • ... insulin and growth hormone. ... Steroid...

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Transcript of Human Biochemistry · HUMAN BODY • HYPOTHALAMUS • ... insulin and growth hormone. ... Steroid...