endocrine chapter 12 in text hormones are important for everything! from breakdown of glucose during...
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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 GlandsEndocrine 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 GlandsExocrine 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 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 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 HormonesSteroid Hormones
Lipid-soluble Derived from cholesterol Made only in adrenal cortex, gonads, and
placenta (in pregnancy) Include androgens (testosterone), estrogens
and progestagens
Amine Hormones Amine Hormones
Small molecules synthesized from one or two amino acids comprise the amine hormones
Include catecholamines (epinephrine and norepinephrine) - they are neurohormones
Hormone ActionsHormone Actions
Hormones– Change the synthesis rate of intracellular
proteins – Alter enzymatic activity – Modify cell membrane transport – Induce secretory activity
Patterns of Hormone SecretionPatterns 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 PancreasHormones 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 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 60-90 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 HormonesPituitary 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)Growth Hormone (GH)
Promotes cell division and proliferation It increases calcium retention, and strengthens and
increases the mineralization of bone. It increases muscle mass through the creation of new
muscle cells (which differs from hypertrophy) It promotes lipolysis, which results in the reduction of
adipose tissue (body fat). It increases protein synthesis and stimulates the
growth of all internal organs excluding the brain.
Exercise, GH, and Tissue Synthesis 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 MedullaHormones 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 CortexHormones 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
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