Compendium 10 Notes PDF

Compendium 10 Notes Lecture 1 Basics of chemical communication - Autocrine - Released by cells and have a local effect on the same cell type from which chemical signals are released - Paracrine - Released by cells and affect other cell types locally without bein...

Compendium 10 Notes Lecture 1 Basics of chemical communication - Autocrine - Released by cells and have a local effect on the same cell type from which chemical signals are released - Paracrine - Released by cells and affect other cell types locally without being transported in the blood - Neurotransmitter - Produced by neurons and secreted into extracellular spaces by presynaptic nerve terminals - Travels short differences and influences postsynaptic cells - Endocrine - Produced by the cells of endocrine glands, it enters the circulatory system and affects distant cells Characteristics of the endocrine system - Body control system where regulation requires duration rather than speed - Glands that secrete chemical messengers (hormones) into the circulatory system (blood) - Hormone characteristics - Produced in small quantities - Transported some distance in the circulatory system - Acts on target tissues elsewhere in the body - Hormone secretion can be - Acute -- sudden release due to a stimulus, e.g. adrenaline in response to stress - Chronic -- small variations over long periods e.g. thyroid hormones - Episodic -- estrogen and progesterone during menstrual cycles - Target cells respond to a hormone because they have the correct receptor Functions of the endocrine system 1. Metabolism 2. Control of food intake and digestion 3. Tissue maturation 4. Ion regulation 5. Water balance 6. Heart rate and blood pressure regulation 7. Control of blood glucose and other nutrients 8. Control of reproductive functions (gametogenesis and pregnancy) 9. Uterine contractions and milk release 10. Immune system regulation Endocrine glands of the body - Pineal gland - Key endocrine gland - Sleep and wake cycles (cycadean rhythm) - Hypothalamus - Central nervous system - Makes key hormones like oxytocin and ADH - Regulates anterior pituitary - Pituitary gland - Anterior and posterior parts - Where most tropic hormones come from - Thyroid gland - Stress response - Growth - Parathyroid gland (on the dorsal aspect of the thyroid gland) - Bone metabolism - Thymus gland - Immune system - Significant changes at puberty - Adrenal gland - Cortex and medulla - Cortex = cortisole and aldosterone - Medulla = adrenaline and noradrenaline - Pancreas - Sugar metabolism - Ovary - Making oocytes and key hormones - Testes - Making sperm and key hormones Nervous vs endocrine - Similarities - Both are associated with the brain - Endocrine -- hypothalamus - Both use chemical messengers as the nervous system used neurotransmitters - E.g. epinepherine - Two systems are cooperative - E.g. some parts of the endocrine system are innervated by the nervous system (adrenal medulla) - Differences - Mode of transport - Axon - Blood - Speed of response - Nervous -- instant/millisecond - Endocrine -- minutes/days Structure of the pituitary gland - 'Master gland' - Connected to the hypothalamus via the infundibulum - Due to their embryonic origins, the two parts are made up of different tissues (posterior as a growth of nervous tissue and the anterior as glandular tissue) - Posterior pituitary (neurohypophysis): extension of the nervous system via the infundibulum - Secretes neuropeptides - Anterior pituitary (adenohypophysis) - Develops from the embryonic oral cavity and secretes traditional hormones The pituitary gland and the hypothalamus - Where the nervous system and endocrine systems interact - The hypothalamus regulates secretions of the anterior pituitary - The posterior pituitary is an extension of the hypothalamus - the hypothalamus makes neuropeptides which travel down the stalk and are released by the posterior pituitary - The pituitary gland produces nine major hormones that - Regulate body functions - Regulate the secretions of other endocrine glands - Hypothalamic control of the posterior pituitary: - Hormones produced in neurons in hypothalamus, stored in the posterior pituitary - Axons from the hypothalamohypophysial tract - Action potentials in these neurons cause hormone release - Hypothalamic control of anterior pituitary - Blood vessels make up hypothalamohypophysial portal system, connect areas - Hypothalamic releasing and inhibiting factors which stimulate or inhibit hormone release of the anterior pituitary Hypothalamus, anterior pituitary, target tissues - Stimuli within the nervous system regulates the secretion of releasing hormones form neurons in the hypothalamus - Releasing hormones pass to anterior pituitary - Releasing hormones stimulate the release of hormones from the anterior pituitary - Anterior pituitary hormones travel in the blood stream to the target tissue which may be another endocrine gland Some examples of hypothalamic hormones (there are lots more) - Growth hormone-releasing hormone - Increases secretion of growth hormone - Prolactin releasing hormone - Causes increased prolactin secretion Anterior pituitary hormones - Growth hormone (GH) - Acts on most cells of the body, overall metabolism and growth - Thyroid-stimulating hormone (TSH) - Stimulates thyroid to secrete T3 and T4 - Adrenocorticotropic hormone (ACTH) - Stimulates the adrenal cortex to secrete cortisol and aldosterone - Melanocyte stimulating hormone - Causes melanocytes to produce more melanin - Luteinising hormone (LH) - Follicle-stimulating hormone (FSH) - Both hormones regulate production of gametes and reproductive hormones - Testes -- to make testosterone and spermiogenesis - Ovaries -- to make estrogen and progesterone, and oogenesis - Prolactin - Role in milk production/lactation Tropic vs non tropic - Tropic hormones - Stimulate the secretion of other hormones form other target tissues - A lot of anterior pituitary hormones are tropic - Non tropic hormones - Initiate an effect Hypothalamus, posterior pituitary, target tissues - Stimuli within the nervous system cause neurons in the hypothalamus to increase or decrease in action potential frequency - Action potentials conducted along neurons from the hypothalamus to posterior pituitary. Axon terminals of these neurons store neurohormones - Action potentials cause the release of neurohormones into the circulatory system - Posterior pituitary hormones travel in the blood to the target tissue Posterior pituitary hormones - Antidiuretic hormone (ADH) - Stimulates increased reabsorbtion of sodium and water from nephrons, so less (more concentrated) urine is produced (water is preserved by the body). If blood pressure decreases then ADH secretion is stimulated. - Also called vasopressin (vasoconstriction, increase blood pressure) - Oxytocin - Uterine contraction during birth - Ejection of milk from lactating breath (let down reflex) Control of hormone secretion -- negative feedback - Anterior pituritary secretes a tropic hormone which travels in blood to target endocrine cell - Hormone from target endocrine cell travels to its target endocrine cell - Hormone from target endocrine cells has negative feedback (opposite) effect on hypothalamus and anterior pituitary to decrease secretion of tropic hormone Control of hormone secretion -- positive feedback - The anterior pituitary secretes a tropic hormone which travels in the blood to the target endocrine cell - Hormone from target endocrine cell travels to its target - Hormone from target endocrine cells has a positive feedback effect on the hypothalamus and anterior pituitary to increase secretion of tropic hormone - E.g. oxytocin in childbirth Growth hormone - Stimulates the uptake of amino acids, protein synthesis (build muscle mass) - Stimulates the breakdown of fats to be used as an energy source - Promotes bone and cartilage growth - Regulates blood levels of nutrients after a meal - Stimulates liver and skeletal muscle to make IGF-1 - These levels peak during deep sleep Thyroid-stimulating hormone, T3 and T4 - Governed by the hypothalamus which sends thyroid releasing hormone down the hypothalamohypophysial portal system which then acts on the anterior pituitary to make TSH, a trophic hormone which works on negative feedback - T3 and T4 act to increase metabolism, body temp, growth and development Thyroid gland - One of the largest endocrine glands - Highly vascular - The only gland which stores hormones - Composed of follicles, follicular cells surrounding, thyroglobulin/thyroid hormones - Iodine and tyrosine are necessary for the production of T3 and T4 - Increased rate of glucose, fat, protein metabolism in many tissues, thus increasing body temperature - Normal growth for many tissues - T3 is triiodothyronine - T4 is thyroxine or tetraiodothyronine ACTH -- adrenocorticotropic hormone - Adrenal glands sit near the superior poles of the kidneys - Inner medulla; outer cortex - Cortisole releasing hormone form the hypothalamus causes the release of ACTH from the anterior pituitary which causes cortisole secretion from the adrenal cortex (a glucocorticoid). - Causes aldosterone secretion from the adrenal cortex (a mineralocorticoid) - Sodium and water balance - Causes androgen (weak sex hormone as they are less potent than other sex hormones) Adrenal medulla - Stress, physical activity and low blood glucose levels act as stimuli to the hypothalamus resulting in increased sympathetic nervous system activity - An increased frequency of action potentials conducted through the sympathetic division of the autonomic nervous system stimulates the adrenal medulla to secrete epinephrine and norephedrine into (CVS) as a result... - Increased release of glucose from the liver into the blood - Increased release of fatty acids from adipose tissue into the blood - Increased heart rate - Decreased blood flow through the blood vessels of most internal organs - Increased blood flow to heart and skeletal muscles - Secretion of hormones prepares the body for physical activity (short-lived response) - Epinephrine = adrenaline - Norepinephrine = noradrenaline Melanocyte stimulating hormone -- MSH - Acts on receptors in skin cells (melanocytes) and stimulates melanin (colour pigment in the skin) - MSH also has a role in regulating appetite and sexual behaviour - Poorly understood Luteinising hormone (LH) and follicle-stimulating hormone (FSH) - Gonadotropin from the hypothalamus stimulates LH and FSH secretion from the anterior pituitary - Gonadotropins: glycoprotein hormones that promote growth and function of the gonads - LH and FSH: - Both hormones regulate the production of gametes and reproductive hormones - From testes -- testosterone: spermatogenesis, secondary sex characteristics - From ovaries -- estrogen and progesterone: sex organ development and characteristics, menstural cycle and pregnancy Prolactin - Non tropic hormone - Breast milk production - Supply is dependent on demand - This is positive feedback, the ore the baby suckles on the breast, the more milk that is produced - Secreted from the anterior pituitary - The release of prolactin is governed by prolactin inhibiting factor and prolactin inhibiting factor from the hypothalamus Oxytocin - Posterior pituitary - Non tropic hormone - Positive feedback - Breast milk release (let down). - Supply is based upon demand Anti-diuretic hormone (ADH) (vasopressin) - Reduced urine formation - Keeps water in the body - Increases blood volume and, thus blood pressure - Hot day/dehydrated = lots of ADH - Diuretics = tea/coffee/alcohol Pancreas - Regulation of insulin secretion - Located along and near to the stomach and intestine - Exocrine gland: produces pancreatic digestive juices - Endocrine gland: consists of pancreatic islets - Alpha cells secrete glucagon - Beta cells secrete insulin Tutorial notes 1. Nervous system Endocrine system -------------------------------------- -------------------------------------------------------- ------------------ Speed of response Quick Slow Duration of response Shorter Longer Mediator molecules Neurotransmitters Hormones Mode of action of mediator molecules Moves across the synapse to the effector or nerve Blood Types of target cells Skeletal muscle, cardiac muscle, smooth muscle, glands Cells 2. Because its 'wireless' chemical messenger, an indirect messenger 3. Types of chemical messengers ------------------------------ ----------- -------------------------------------------------------------------------------------- 1 Endocrine Work at a far distance in the blood system 2 Paracrine More regionally active, small distance, receptors are close to the site of synthesis 3 Autocrine Work on themselves or the neighbouring cell 4. Because it makes hormones which work on other endocrine organs 5. +-------------+-------------+-------------+-------------+-------------+ | Hormone | Tropic or | Organ or | Hormones | Effects on | | produced by | non-tropic | cells it | produced by | the body | | the | | acts on | organs | | | anterior | | | | | | pituitary | | | | | +=============+=============+=============+=============+=============+ | TSH | Tropic | Thyroid | Thyroxine | Thermoregul | | | | gland | | ation | | | | | T3 and T4 | | | | | | | Appetite | | | | | | | | | | | | Metabolism | +-------------+-------------+-------------+-------------+-------------+ | ATCH | Tropic | Adrenal | Cortisol | Anti-stress | | | | gland | | hormone | | | | | Aldosterone | | | | | | | Glucose | | | | | Androgens | metabolism, | | | | | | blood | | | | | | pressure, | | | | | | reabsorptio | | | | | | n | | | | | | of water, | | | | | | precursors | | | | | | of sex | | | | | | hormones | +-------------+-------------+-------------+-------------+-------------+ | FSH and LH | Tropic | Testes or | Testosteron | Regulating | | | | overies | e | gametogenes | | | | | and | is | | | | | estrogen | | | | | | | Secondary | | | | | | sexual | | | | | | characteris | | | | | | tics | +-------------+-------------+-------------+-------------+-------------+ | GH | Tropic and | Long bones | IGF 1 - | Growth of | | | Non tropic | | Liver | muscles and | | | | Liver and | (protein | bones | | | | other | synthesis) | | | | | target | | | | | | cells | | | +-------------+-------------+-------------+-------------+-------------+ | Prolactin | Non tropic | Mamory | None | Lactation | | | | glands | | | +-------------+-------------+-------------+-------------+-------------+ | MSH | Non tropic | Skin | None | Skin | | | | | | pigment, | | | | | | appetite | | | | | | and sexual | | | | | | behaviours | +-------------+-------------+-------------+-------------+-------------+ 6. Receptors, target cells, altering activities, stimulating new or unusual activity, steroid or amino acid based, neural, hormonal, humoral, negative feedback, pituitary, the releasing or inhibiting hormones, hypothalamus, neuroendocrine 1. In the anterior pituitary gland, CRH binds to and stimulates cells that secrete adrenocorticotropic hormone (ACTH). 2 -------------------------------------------------------------------------------------------------------------------------------------------------------------------------------- --- Cortisol has a negative-feedback effect because it inhibits CRH release from the hypothalamus and ACTH release from the anterior pituitary. 5 ACTH travels in the blood circulation and binds to receptors in the cells of the adrenal gland (cortex) which stimulates the secretion of glucocorticoids, primarily cortisol. 3 Corticotropin-releasing hormone (CRH) is released from the hypothalamus in response to low blood glucose levels or stress. 1 Cortisol acts on target tissues, resulting in an increase in fat and protein breakdown and increased glucose levels. 4 1. Signals in the form of action potentials are sent from the hypothalamus to the posterior pituitary 2 ------------------------------------------------------------------------------------------------------------------------------ --- Circulating oxytocin increases contractions of the uterus, and milk ejection from the lactating breast 4 The posterior pituitary receives the action potentials and releases oxytocin into the blood circulation. 3 Stretch of the uterus and the uterine cervix or stimulation of the breasts' nipples triggers the hypothalamus. 1 Oxytocin levels continue to rise, the hypothalamus and pituitary continue to be stimulated until a significant change occurs 5 2. Yes this cycle does need to end, the uterus will stop contracting once the baby has been born and the breasts will stop producing milk once the baby stops requiring milk and starts eating solids smaller contractions of the uterus from oxytocin during breastfeeding help the uterus shrink back to its original shape +-----------------+-----------------+-----------------+-----------------+ | Endocrine | Organ | Hormone | Body/systemic | | disorder | affected/how | affected/how | effects | +=================+=================+=================+=================+ | Adrenal | Underactive | Too little | Fatigue, | | insufficiency | adrenal gland | cortisol is | weakness, | | | | produced and | weight loss, | | | Specifically | sometimes too | low blood | | | cortex | little | pressure, skin | | | | aldosterone | changes, salt | | | | | cravings, | | | | | nausea and | | | | | vomiting, mood | | | | | changes | +-----------------+-----------------+-----------------+-----------------+ | Cushing's | Overactive | Too much | Weight gain, | | disease | adrenal gland | cortisol is | skin changes, | | | | produced | muscle | | | Often caused by | | weakness, high | | | a tumour in the | | blood pressure, | | | pituitary gland | | mood changes | | | | | and menstrual | | | | | irregularities | +-----------------+-----------------+-----------------+-----------------+ | Gigantism | The anterior | Excess growth | Bones and body | | | pituitary is | hormone | parts grow very | | | overactive -- a | | fast/ tall | | | tumour in he | | | | | cells that make | | | | | growth hormones | | | +-----------------+-----------------+-----------------+-----------------+ | Hyperthyroidism | Thyroid -- | Too much | Weight loss, | | | immune disorder | thyroid hormone | anxiety, | | | | | weakness, high | | | | | body temp, | | | | | sexual | | | | | disfunction, | | | | | heart rate | | | | | fluctuation, | | | | | enlarged | | | | | thyroid gland | +-----------------+-----------------+-----------------+-----------------+ | Type 1 diabetes | Pancreas -- | Not enough | Immune system | | | islettes of | insulin | effected, sugae | | | Langerhans | produced | is not entering | | | | | the cells, not | | | Insulin beta | | making enough | | | cells | | ATP, sugar | | | | | remains in the | | | | | blood stream | | | | | increasing | | | | | thirst with | | | | | increased | | | | | urination, | | | | | weight loss and | | | | | fatigue | +-----------------+-----------------+-----------------+-----------------+ | Hypothyroidism | Thyroid | Not enough | Fatigue, poor | | | | thyroid hormone | digestion, poor | | | | is produced | heart | | | | | regulation, | | | | | slow | | | | | metabolism, | | | | | menstrual | | | | | disturbance | +-----------------+-----------------+-----------------+-----------------+ | precocious | Gonads (testes | Sex hormones | Early puberty, | | puberty | and ovaries) | | early physical | | | | | changes leading | | | | | to earlier | | | | | sexual maturity | +-----------------+-----------------+-----------------+-----------------+