Unit 9 - Endocrine System Flashcards
What are some characteristics of the endocrine system?
- works together with the nervous system
- maintains homeostasis of the body
- produces messengers (hormones) that coordinate the body’s response to different situations and stimulus
- reacts slowly to changes, but it sustains the response for long periods
What is the pathway for the endocrine system signalling?
endocrine gland cells -> hormones (messengers) -> (blood stream) to target tissues
What are the differences between the nervous system and the endocrine system?
Overall function - both maintenance of homeostasis
Reaction to stimuli:
endocrine - slow
nervous - short
Duration of effects:
endocrine - long
nervous - short
Target tissues:
endocrine - most of the body cells and tissues
nervous - muscle and glandular tissues
Chemical messenger:
endocrine - hormone
nervous - neurons
Communication with target tissues:
endocrine - via bloodstream (long distance)
nervous - via synapses (short distance)
What are the basic unit of the endocrine system?
endocrine glands (ductless glands)
Where are the endocrine glands located?
throughout the body
What do the endocrine glands secrete?
small amounts of hormones directly in the bloodstream
What do exocrine glands do?
secrete their products onto epithelial surfaces through the ducts
What are hormones?
chemical messengers produced by endocrine glands
Where do hormones travel?
in the bloodstream to all parts of the body
What do hormones bind to?
they bind to their particular receptors in or on the target cells
What are the three groups of hormones?
peptide hormones
steroid hormons
monoamine hormones
What are some characteristics of peptide hormones?
- contains 200 or more AA
- hydrophillic (soluble in water)
- easily travels in the blood plasma
What are some characteristics of steroid hormones?
- lipids synthesized from cholesterol
- hydrophobic (insoluble in water)
- must bind to a transporter protein to travel in the plasma
- can easily diffuse into cell membrane
What are some characteristics of monoamine hormones?
- derived from amino acids and retain an amino group
- contains both hydrophillic and hydrophobic type of hormones
What is hormone secretion controlled by?
feedback system
- levels of the hormone “feed back” the gland that produces it
- this feedback can increase or decrease the production levels of the hormone
What is negative feedback vs positive feedback?
negative feedback - rising levels of the hormone decrease the activity of the gland
positive feedback - falling levels of the hormone increase the activity of the gland
What is the hormone feedback cycle of the anterior pituitary gland and TSH?
Anterior pituitary gland produces thyroid stimulating hormone (TSH) which activates the thyroid gland which produces thyroid hormones, if the levels of thyroid hormone drop too low/raise too high, feedback goes to the anterior pituitary gland to produce more/less TSH
What is the hypothalamus a part of?
the diencephalon of the brain
What does the hypothalamus control?
hormone release from the pituitary gland by producing, releasing, or inhibiting hormones under the control of nervous impulses
Where is the pituitary gland located?
ventral to the hypothalamus and is attached to it by a slender stalk
What do blood vessels and nerve fibers do in the hypothalamus stalk?
blood vessels and nerve fibers in the stalk enable the hypothalamus to control the activity of the pituitary gland and therefore most of the rest of the body
What is the relationship of the hypothalamus and posterior pituitary?
- neurosecretory cells in the hypothalmus produces hormones that are transported down nerve fibers to the posterior pituitary
- the hormones are stored here and their release is controlled by nerve impulses from the hypothalamus
What is the relationship between the hypothalamus and the anterior pituitary?
- hormones from the hypothalamus are secreted into portal blood vessels
- carry them to the anterior pituitary which brings info in
What is another name for the pituitary gland?
hypophysis
What do the hormones in the pituitary gland do?
direct the activity of other endocrine glands in the body
What does the anterior pituitary develop from?
develops from glandular tissue in the embryo
What does the posterior pituitary develop from?
develops from nervous system in the embryo
What is the function of the posterior pituitary gland?
- it does not produce hormones
- it stores and releases two hormones produced in the hypothalamus
What is the function of the anterior pituitary gland?
- produces hormones when stimulated by the hypothalamus and/or when stimulated by direct feedback by target tissues
What do the posterior and anterior pituitary glands look like under a microscope?
posterior - lighter pink
anterior - darker pink
What are the hormones that the anterior pituitary gland produces?
- growth hormone (GH)
- prolactin
- thyroid-stimulating hormone (TSH)
- andrenocortictropic hormone
- follicle-stimualting hormone (FSH)
- luteinizing hormone (LH)
- melanocyte-stimulating hormone
What does the growth hormone do?
- it acts in all body cells to help to regulate the metabolism of proteins, carbohydrates and lipids
- the effects of GH on protein metabolism is to encourage anabolism (enhance tissue growth)
- it causes mobilization of fat tissue and breakdown of lipids for energy production
- it discourages cells to use carbohydrates as energy sources - causing increasing levels of blood glucose
Why do we castrate right after birth?
- less aggression
- when muscles develop, they can use more fat+protein stores
Why do fatty acids release more energy than glucose when they are oxidized?
because they have a lot more carbons in their backbone than glucose
What is the GH effects on muscle tissue? (graph)
free fatty acid graph:
- free fatty acids indicate lipid mobilization on y-axis
- one line is GH infusion the other is saline infusion
- GH infusion has more FFA’s because gh triggers lipid deposition in the body
Glucose graph:
- glucose infusion rate GIR on y-axis
- insulin is injected when the lines go up (insulin is important for glucose uptake)
- GH infusion has more glucose because gh discourages cells to use carbohydrates as energy sources causing increasing levels of blood glucose
What does prolactin do?
- helps trigger and maintain lactation - secretion of milk by mammary glands
- its production and release is stimulated by nursing or milking of the teat. nursing or milking is ceased, its production is ceased as well