Endocrine System Flashcards
QUESTIONS
What are the 2 classes of glands? What do they produce? Which have ducts? Which are endocrine glands? (5) Which one is the neuroendocrine organ? Which have both endocrine and exocrine functions? (3)
Exocrine glands
- Nonhormonal substances (sweat, saliva)
- Have ducts to carry secretion to membrane surface
Endocrine glands
- Produce hormones
- Lack ducts
- pituitary, thyroid, parathyroid, adrenal, and pineal glands
-Hypothalamus is neuroendocrine
Both = Pancreas, gonads, placenta
What are the two types of hormones? Do they cross the plasma membrane? What do they act upon? How do they act at receptors? Which hormones are they?
Amino acid-based hormones
- water soluble hormones. Do not cross phospholipid bilayer
- Act on plasma membrane receptors
- Act via G protein second messengers
- all amino acid–based hormones except thyroid hormone
Steroids (Synthesized from cholesterol)
- travel through membrane & into nucleus to affect protein synthesis
- Act on intracellular receptors that directly activate genes
- steroid and thyroid hormones
- gonadal and adrenocortical hormones, not epi
QUESTIONS
What are the three ways to stimulate hormone production? What feedback system do they regulate on to maintain what? How is each stimuli triggered? What is an example of each?
-Controlled by negative feedback systems to maintain homeostasis
Humoral stimuli
- Changing blood levels of ions and nutrients
- Declining blood Ca2+ concentration stimulates parathyroid glands to secrete PTH (parathyroid hormone) to increase blood Ca
Neural stimuli
- Nerve fibers
- Sympathetic nervous system fibers stimulate adrenal medulla to secrete epi & norepinephrine
Hormonal stimuli
- Hormones stimulate other endocrine organs to release other hormones
- Hormones from hypothalamus triggers Anterior pituitary gland that secretes hormones that stimulate other endocrine glands to secrete other hormones.
QUESTIONS
Compare and contrast the differences between the ant and post lobe of the pituitary gland. What tissue is each made out of? Where do they originate? What kind of connections do they have? *What hormones do they secrete?
Anterior pituitary (lobe)
- Glandular tissue
- Originates as outpocketing of oral mucosa
- Carries releasing and inhibiting hormones
- makes GH and prolactin, LH, ACTH, FSH, TSH
- anterior pituitary gland has the hypophyseal portal system
Posterior pituitary (lobe)
- Neural tissue
- Downgrowth of hypothalamic neural tissue
- synthesize neurohormones oxytocin and antidiuretic hormone (ADH)
- posterior pituitary gland has neurohypophysis
QUESTIONS
How is the pituitary and the hypothalamus connected?
- anterior: thru the hypothalamic-hypophyseal tract
- posterior: vascular connection to the hypothalamus
QUESTIONS
What are the steps of the cAMP signaling mechanism? (6)
- hormone (first messenger) binds to receptor
- receptor turns on G protein
- G protein activate adenylate cyclase
- adenylate cyclase converts ATP to cAMP (2nd messenger)
- cAMP activates protein kinases that phosphorylates proteins (which activates and inactivates)
- cAMP degraded by phosphodiesterase
QUESTIONS
What are the steps of the PIP2 calcium signaling mechanism after the G protein is activated?
*What splits PIP2 into DAG and IP3?
- phospholipase C splits PIP2 into DAG and IP3
- DAG activates protein kinase
- IP3 causes Ca release (2nd messanger)
- Ca alters enzyme activity & channels or binds to regulatory protein calmodulin
- ca bound calmodulin activates enzymes that amplify cellular response
The endocrine system acts with the ___ system to coordinate and integrate activity of body cells
nervous system
Endocrine system Influences metabolic activities via ___ transported in blood
hormones
endocrine response is slower/faster than nervous system?
slower
What is Endocrinology
Study of hormones and endocrine organs
What are the 5 functions of the endocrine system?
Reproduction
Growth and development
Maintenance of electrolyte, water, and nutrient balance of blood
Regulation of cellular metabolism and energy balance
Mobilization of body defenses
Other tissues and organs that produce hormones (6)
Adipose cells, thymus, and cells in walls of small intestine, stomach, kidneys, and heart
What are hormones? What do they travel in? (2)
long-distance chemical signals; travel in blood or lymph
What is autocrines and paracrines? Are they part of the endocrine system? Why?
Autocrines: chemicals that affects same cells that secrete them
Paracrines: chemicals that affect cells other than those that secrete them
No - because they are local, not long-distance
Steroids are produced by which 2 structures?
adrenal cortex & gonads
What are target cells? How are they affected by hormones?
- Tissues with receptors for specific hormone (reason why hormones circulate systemically but only cells with receptors for that hormone affected)
- Hormones alter target cell activity
What are the steps of the intracellular receptors & direct gene activation mechanism of steroids and thyroid hormones? (5)
*last step
- Diffuse into target cells and bind with intracellular receptors
- Receptor-hormone complex enters nucleus; binds to specific region of DNA
- Prompts DNA transcription to produce mRNA
- mRNA directs protein synthesis
- Promote metabolic activities, or promote synthesis of structural proteins or proteins for export from cell
What 3 factors does target cell activation depend on?
- # receptors
- type of hormone
3 affinity between receptor and hormone
How do hormones influence number of their receptors? (2)
Up-regulation—target cells form more receptors in response to low hormone levels
Down-regulation—target cells lose receptors in response to high hormone levels
True or false
Nervous system can override normal endocrine controls (Nervous system modifies stimulation of endocrine glands and their negative feedback mechanisms)
How is the hypothalamus related to this phemomenon?
true
-under severe stress, hypothalamus and sympathetic nervous system activated to increase body glucose levels rise