Endocrine Chapter 12 in text Hormones are important for EVERYTHING! From breakdown of glucose during exercise to initiating orgasm in humans read on to find out more…

How to use online lectures There are lecture slides and notes to explain- similar to what I would chat about in the lecture (look below the slides!) You can either print them off (choose to print “notes pages” rather than just the slides/ handouts) Read through with chapter 12 of the text and use text/internet to check terms/ concepts for further information if you don’t understand Also feel free to post a discussion question on webCT and I will get back to you ASAP Good luck!

Endocrine Glands Secrete hormones into the blood Lack ducts (ductless), but discharge their substances directly into the extracellular space around the gland Hormones then diffuse into the blood for transport throughout the body Eg. The adrenal medulla is an endocrine gland that secretes epinepherine and norepinepherine into the blood that targets many different tissues to cause a sympathetic response.

Exocrine Glands Contain secretory ducts that lead directly to the specific compartment or surface that requires the hormone Include the sweat glands and upper digestive tract glands The nervous system controls almost all exocrine glands

Hormone Classification Peptide hormones – Composed of linked amino acids Steroid hormones – Derived from cholesterol and amine hormones Amine hormones – Derived from a single type of amino acid

Peptide Hormones Range from small peptides of only three amino acids to large proteins and glycoproteins Are water-soluble Bind to surface membrane receptors and act through a second messenger Signal transduction: – G-protein coupled receptors – Second messenger – A cascade of metabolic processes

Steroid Hormones Lipid-soluble Derived from cholesterol Made only in adrenal cortex, gonads, and placenta (in pregnancy) Include androgens (testosterone), estrogens and progestagens

Amine Hormones Small molecules synthesized from one or two amino acids comprise the amine hormones Include catecholamines (epinephrine and norepinephrine) - they are neurohormones

Hormone Actions Hormones – Change the synthesis rate of intracellular proteins – Alter enzymatic activity – Modify cell membrane transport – Induce secretory activity

Patterns of Hormone Secretion Hormones are secreted: – On an as-needed basis – At regular intervals during a 24-hour cycle, referred to as diurnal variation – Some secretory cycles span several weeks, whereas others follow daily cycles

Major hormones you should know

Hormones of the Pancreas Insulin – Regulates glucose metabolism by facilitating glucose uptake in all tissues 9mostly muscles and liver) except the brain in response to hyperglycemia (hyper = high) Glucagon – Stimulates the catabolism (breakdown) of liver glycogen to increase glucose output to prevent hypoglycemia (hypo = low)

INSULIN- Controller of blood glucose levels

Diabetes Mellitus Type 1 diabetes results from the body's failure to produce insulin. Type 2 diabetes results from insulin resistance (a condition where the body fails to properly use insulin) combined with relative insulin deficiency Gestational diabetes- diabetes occurring only while a woman is pregnant- afflicts about 4% of all pregnant women

Blood glucose levels <4 mmol/L – Too low- give jelly beans/ juice etc 4-6 mmol/L- Average 12 mmol/L – Too high, but doesn’t require insulin yet 15 mmol/L- Too high- requires insulin

Considerations for exercise: Exercise minutes after insulin injection Watch for signs of hypoglycaemia (lethargy, slurring words etc) Keep hydrated Keep some glucose on hand- jelly beans or fruit juice

Benefits of exercise for diabetics Glycaemic control- acute decrease in blood glucose levels and increased insulin sensitivity of peripheral tissues (meaning that there is a stabilisation of blood glucose levels). As these effects may last for a few hours to a few days (av = 48 hours) there is a stabilisation of blood glucose levels

Pituitary Hormones Anterior lobe – Growth hormone (GH) – Prolactin (PRL) – Tropic hormones ACTH- corticotropin FSH- Follicle stimulating hormone LH- luteinizing hormone Posterior lobe – Oxytocin- “cuddle hormone”  childbirth and orgasm (not in that order!) – Antidiuretic hormone ADH or vasopressin

Growth Hormone (GH) Promotes cell division and proliferation It increases calcium retention, and strengthens and increases the mineralization of bone.calciummineralization of bone It increases muscle mass through the creation of new muscle cells (which differs from hypertrophy)musclehypertrophy It promotes lipolysis, which results in the reduction of adipose tissue (body fat).lipolysis adipose tissue It increases protein synthesis and stimulates the growth of all internal organs excluding the brain.protein synthesisbrain

Exercise, GH, and Tissue Synthesis GH secretion increases a few minutes after exercise begins Increasing exercise intensity increases GH production and secretion GH promotes its anabolic, tissue-building effects (mediated via somatomedins) on diverse tissue including bone and skeletal muscle

Too much GH!!

Thyroid hormones Major endocrine gland Secretes hormone that is essential to proper growth, development and differentiation of all cells of the human body Failure to secrete thyroid hormones = hypothyroidism. Too much thyroid hormone = hyperthyroidism

Hypothyroidism Mostly due to lack of thyroid gland. - Also linked to iodine deficiency (note to self- buy iodised salt!) Goiter

Hormones of the Adrenal Medulla Catecholamines – Neural outflow from the hypothalamus directly influences adrenal medulla secretions Epinephrine (80%) and norepinephrine (20%) – Increase heart rate, contractility, and blood pressure – Rate of secretion is strongly influenced by exercise intensity

Hormones of the Adrenal Cortex Mineralocorticoids – Aldosterone regulates sodium reabsorption in the kidneys’ distal tubules Glucocorticoids – Cortisol regulates blood glucose concentrations via its permissive interactions with glucagon and catecholamines Androgens – Dehydroepiandrosterone (DHEA)

Hormonal responses to exercise