Niyogi Lectures 13-14 Flashcards
The central nervous system and endocrine system cooperate to regulation homeostasis through extensive feedback loops.
The CNS works over a _____ term and the ES work over a _____ term.
The CNS works over a short term and the ES works over a long term
Compare the endocrine and nervous systems.
Define gland.
organ/tissue responsible for synthesis and secretion of cellular products
Define edocrine
secretion of material into extracellular space or blood vessels; includes autocrine, paracrine and neuro-endocrine
Explain local regulation using the terms autocrine and paracrine
What is distance regulation in the endocrine system?
Key terms: endocrine regulation, neuroendocrine regulation
Define hormone and list it’s functions.
Hormone: signalling molecule secreted by endocrine cells
Hormones regulate physiology, behaviour, and development
Define exocrine
Secretion of material onto a body surface or into a duct
Summarize the general chemistry of hormones using the terms amines, peptides, and steroids
This is not an exhaustive list; there are some hormones that do not fit into these categories
What are the signalling mechanisms of non-steroid hormones (derived from amino acids)? Give two examples.
Bind to plasma membrane receptors
e.g. epinephrine, insulin
What are the signalling mechanisms of steroid hormones (lipids derived from cholesterol). Give two examples.
Bind to intracellular receptors
e.g. insect developmental hormones, human sex hormones
Several hormones can be produced in a synthesis pathway. The molecule produced depends on enzyme gene expression in secretory cell.
These molecules can act as a hormone or a neurotransmitter.
Describe this synthesis pathway and the products at each step.
Hydrophilic hormones are stored in ________ ________ before secretion from the cell.
secretory vesicles
List the 6 steriods that are made from cholesterol.
Cortisol
Aldosterone
Androgens
Estrogens
Progesterone
Ecdysons
Are hydrophobic hormones (steroids) stored in the cell?
Hydrophobic hormones diffuse out of the cell after synthesis
How are hormone levels in the blood regulated?
- altering the rate of synthesis
- altering the rate of secretion
- removal mechanisms in the liver and kidney of vertebrates
- conversion of inactive form to active form of target tissue (T4 to T3 by deiodinase in the liver)
- homeostatic feedback loops
True or false? Virtually all tissues produce an endocrine messenger.
true
True or false? Cells will respond to most hormones.
False. Only cells with a specific receptor protein will respond to a hormone.
Summarize the role of the hypothalamus, pineal gland, pituitary, thyroid and parathyroid, adrenal cortex and medulla, pancreas, and ovaries/testes in the endocrine system.
What is the main centre of control for the endocrine system?
the hypothalamus
Note this explains the close relationship between the endocrine system and the nervous system
What tissues exclusively produce steroid hormones?
Only the adrenal gland and sex organs produce steroid hormones
Explain the brain-pituitary connection in the endocrine systems of vertebrates.
The anterior lobe produces and releases hormones. The posterior lobe does not produce hormones per se—this is done by nerve cells in the hypothalamus—but it does release them into the circulation.
What hormones are released by the posterior vs anterior pituitary?
What is the function of growth hormone?
Promotes protein synthesis and use of body fat for energy, and thus has a very broad effect. It also promotes development and enlargement of all body parts so it is essential for normal growth and development.
What is the result of an overproduction of growth hormone? Underproduction?
gigantism and dwarfism
What tissue controls metamorphosis in bullfrogs?
the thyroid gland
What is the influence of the thyroid gland in humans?
Produces T4 (thyroxine) and T3
Maintains normal blood pressure, heart rate, muscle tone
Roles in digestion, reproduction, calcium homeostasis (calcitonin)
What is the result of insufficient T3 and T4 hormone?
hypothyroidism (goiter)
enlargement of the thyroid
Body responds to stress in two phases…
and different adrenal gland hormones mediate both phases
Acute response: almost immediate and is due to activation of sympathetic division
Chronic repsonse: delayed by a few minutes and is due to activation of hypothalamo-pituitary axis
Describe the acute response to stress of the endocrine system.
Adrenal gland secretes two hormones (75% epinephrin and 25% norepinephrine) when the sympathetic NS is maximally active. This prolongs the body response of fight or flight.
What is the cardiovascular, respiratory, metabolic, and nervous system response to the acute phase of endocrine stress?
List the physiological effects of the sympathetic vs parasympathetic nervous system.
Describe the chronic phase in endocrine stress response.
Can last from minute to days:
Prepares the body to cope with stress over a long time. Due to glucocorticoid hormones from the adrenal cortex (cortisol in humans, rodents, and teleost fish; corticosterone in all other vertebrates)
What parts of the adrenal gland produce which hormones?
What are the major actions of glucocorticoids in stress?
Describe the Hypothalamis-Pituitary-Adrenal axis (Chronic Stress Response homeostatic control).
Neuroendocrine regulation of digestion in mammals
make a chart of this
Parasymp and symp at the top
hormones on the side
the effects
What sex hormones are produced and secreted by the gonads and how are they regulated?
Estrogens- maintain female reproductive system and develop female features
Progestins- prepare uterus to support embryo
Androgens- stimulate embryo to become male, maintain male reproductive system
Regulated by hypothalamus and anterior pituitary
Describe endocrine regulation of blood glucose levels using the terms negative and positive feedback.
HIGH BLOOD GLUCOSE
Negative feedback: alpha cells of pancreas stop secreting glucagon so liver ceases glucose secretion into the blood
Positive feedback: beta cells secrete insulin which causes fat cells to take in glucose from the blood
LOW BLOOD GLUCOSE
Positive feedback: Glucagon released by the alpha cells of the pancreas cause the liver to release glucose into the blood stream
Negative feedback: beta cells of the pancreas stop releasing insulin so fat do not continue to consume glucose in the blood
What is follicle-stimulating hormone?
Follicle-stimulating hormone (FSH) is a gonadotropin, a glycoprotein polypeptide hormone. FSH is synthesized and secreted by the gonadotropic cells of the anterior pituitary gland and regulates the development, growth, pubertal maturation, and reproductive processes of the body.
What is luteinizing hormone?
Luteinizing hormone is a hormone produced by gonadotropic cells in the anterior pituitary gland. The production of LH is regulated by gonadotropin-releasing hormone from the hypothalamus. In females, an acute rise of LH known as an LH surge, triggers ovulation and development of the corpus luteum.
LH plays an important role in sexual development and functioning. In women, LH helps control the menstrual cycle. It also triggers the release of an egg from the ovary. This is known as ovulation.
