Human Biochemistry. Hormones

Transcription

1 Human Biochemistry Hormones

2 THE ENDOCRINE SYSTEM

3 THE ENDOCRINE SYSTEM

4 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 can have an effect on pretty much ALL the organ systems! Hormones control many developmental changes like PUBERTY!

5 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!

6 MAJOR GLANDS OF THE HUMAN BODY HYPOTHALAMUS PITUITARY GLAND THYROID GLAND PARATHYROID GLAND PANCREAS ADRENAL GLANDS KIDNEYS FEMALE OVARY MALE TESTES

7 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.

8 2 Types of Hormones STEROID HORMONES PROTEIN HORMONES Fat soluble! Water soluble! Steroid hormones are made from cholesterol and include the sex hormones and cortisol. Protein hormones include insulin and growth hormone. These hormones are chains of amino acids.

9 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.

10 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.

11 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!

12 The Pituitary 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 =

13 THE ENDOCRINE SYSTEM The 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.

14 THE ENDOCRINE SYSTEM Neurons 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.

15 THE ENDOCRINE SYSTEM HYPOTHALAMUS HORMONE-RELEASING FACTOR SMALL BLOOD VESSELS ANTERIOR LOBE OF PITUITARY GLAND VARIOUS HORMONES ARE RELEASED HORMONES ACT ON OTHER PARTS OF THE BODY

16 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.

17 ANTERIOR LOBE PITUITARY HORMONES HORMONE TARGET FUNCTION Thyroid-stimulating hormone (TSH) Thyroid gland -Stimulates the release of thyroxine from thyroid - thyroxine regulates cell metabolism. Adrenocorticotropic hormone (ACTH) Somatotropin (STH), or growth hormone (GH) Adrenal cortex Most cells - Stimulates release of hormones involved in stress responses. - Promotes growth Follicle-stimulating hormone (FSH) Luteinizing hormone (LH) Prolactin (PRL) Ovaries, testes Ovaries, testes Mammary glands - In females, stimulates follicle development in ovaries. - In males promotes development of sperm in testes. -In females, stimulates ovulation and formation of the corpus luteum - in males, stimulates the production of the sex hormone testosterone Stimulates and maintains milk production in lactating females

18 POSTERIOR LOBE PITUITARY HORMONES HORMONE TARGET FUNCTION Oxytocin Antidiuretic hormone (ADH) Uterus, mammary glands Kidneys -Initiates strong contractions - triggers milk release in lactating females - Increases water reabsorption by the kidneys

19 WATER BALANCE Antidiuretic hormone (ADH) = helps to regulate the osmotic pressure of body fluids by causing the kidneys to increase water reabsorption. 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 19

20 Thyroid Gland Hormones HORMONE TARGET FUNCTION T3 Many different cells - Regulates basal metabolic rate & protein synthesis T4 Thyroxine Many different cells - Regulates basal metabolic rate & protein synthesis 20

21 Adrenal Gland Hormones HORMONE TARGET FUNCTION Adrenaline (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 21

22 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 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. 22

23 Pancreas Hormones HORMONE TARGET FUNCTION 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 23

24 Sugar Metabolism Regulation 24

25 Sex Hormones 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 25

26 Who do we look like? 26

27 Menstruation Cycle 1 FSH causes estrogen to rise 2 LH stimulates the egg release 3 Progesterone increases 4 Hormone production decreases and menstruation begins 27

28 Oral Contraceptives 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? 28

29 Roid Rage Anabolic steroids mimic testosterone and increase protein synthesis and build up cellular tissue Anabolism = building up 29

30 Anabolic Steroids GOOD Can be used to trigger puberty Stimulate bone growth and appetite in cancer patients BAD Increases blood pressure Bad temper Increases LDL cholesterol Causes liver damage Decreased sperm count Acne Increases muscle mass 30

31 Try it! 31