Endocrine Physiology and Pathology Flashcards
What is the endocrine system?
What is an important job of the endocrine system?
Acts with the nervous system and coordinates all the activity of tissues and organs, but is slower than the nervous system.
To main homeostasis!
What is the number one function of the endocrine system?
Hormones- amines, steroids etc. are all secreted by glands in the body via the endocrine system and transported via blood
What all does the endocrine system control?
Reproduction
Control of blood pressure
Maintenance of electrolyte, water, and nutrient balance of blood
Regulation of cellular metabolism and energy balance
Responses of cardiac cells
Growth and development
Homeostasis
What is the difference between endocrine and exocrine hormones?
What are examples of both systems?
Exocrine glands act directly and are nonhormonal substances (sweat, saliva, GI secretions) they also have ducts to carry secretion to membrane surface
Endocrine glands produce hormones and lack ducts
What are the different types of hormones?
Autocrine- Chemicals that exert effects on same cells that secrete them
Paracrine- Locally acting chemicals that affect cells other than those that secrete them
Local Chemical Messengers
What are positive and negative feedback mechanisms with relation to regulation of hormonal concentration?
What are some salient factors that determine the response of the target tissues to hormones?
What are the names of common endocrine hormones and which gland secretes them?
What are the endocrine glands?
Pituitary
Thyroid
Parathyroid
Adrenal
Pancreas
Pineal Gland
What is the main organ that links the nervous system and the endocrine system?
Hypothalamus is the neuroendocrine organ
Are glands exclusively exocrine or endocrine?
What is an example?
NO, some glands can have both endocrine and exocrine functions
Pancreas- secrete insulin and glucagon
What other tissue/ organs produce hormones?
Adipose cells
Thymus
Cells in walls of small intestine
Stomach
Kidney
Heart
What is the main gland of the endocrine system?
Pituitary Gland
What is a hormone?
Long distance chemical signals that travel in lymph and blood
What are the 3 major classes of endocrine hormones? What does each class do?
- Amines- Release into blood
- Peptide hormones- Stored in secretory vesicles in the gland after synthesis and released into blood
- Steroids- not stored in secretory vesicles and released into blood
What do hormones as as?
What are the mechanisms of hormone action?
Hormones act as receptors depending on their chemical nature and receptor location
- Water soluble hormones
- Lipid Soluble hormones
What is the base of water soluble hormones? What is the exception?
What do they act on ?
What can water soluble hormones not do?
Amino acid based hormones except thyroid hormone.
Water soluble act on:
- Plasma membrane receptors
- Act via G protein second messengers
They cannot enter the cell
What is the base of lipid soluble hormones?
What do they act on ?
What can lipid soluble hormones do?
Steroid and thyroid hormones
Act on intracellular receptors that directly activate genes
They can enter the cell because they are hydrophobic and lipid soluble
What is the water soluble pathway?
Is it quick or slow?
Quick pathway- works in seconds
- Hormone (1st messenger) binds receptor
- Receptor activates G protein (Gs)
- G protein activates adenylate cyclase
- Adenylate cyclase converts ATP to cAMP (2nd messenger)
- cAMP activates protein kinases
- Reponses of target cell (activates enzymes, stimulates cellular secretion, opens ion channel, etc.)
What are the other signaling pathways?
Hormone binding stimulates phospholipase C which produces IP3 and calcium is released
What is the lipid soluble hormone pathway?
How quick is the pathway?
Pathway is slow and works in hours because of transcription and translation
- The steroid hormone diffuses through the plasma membrane and binds an intracellular receptor
- The receptor hormone complex enters the nucleus
- The receptor hormone complex binds a specific DNA region
- Binding initiates transcription of the gene to mRNA
- The mRNA directs protein synthesis
How is blood concentration of circulating hormones controlled?
Which is most common?
Feedback control mechanisms
- Negative Feedback control
- Positive feed back control
Negative feedback is the most common
What does negative feedback control do?
Which type of control does this mechanism produce?
What is an example?
Successful physiological action results in inhibition of hormonal release
Negative feedback loops are stabilizing
IE: Regulation of thyroid hormone
What does positive feedback control do?
Which type of control does this mechanism produce?
What is an example?
Successful physiological action results in further increase in hormonal release
Positive feedback loops are destabilizing
IE: Hormonal control of development of the ovarian follicle and ovulation
What are the other factors affecting target cell responses?
What does each response do?
Can multiple hormones act on the same target at the same time?
- Permissiveness
- One hormone cant exert its effects without another hormone being present - Synergism
- More than one hormone produces same effects on target cell - Antagonism
- One or more hormones opposes action of another hormone
YES!
What is an example of permissiveness?
Thyroid hormone with reproductive hormones
What is an example of synergism?
Follicle stimulating hormone and Luteinizing hormone on ovulation -> amplification
What is an example of antagonism?
Insulin and glucagon glycogen storage
- Insulin promotes while glucagon antagonizes
What are 7 endocrine gland examples?
Hypothalamus
Anterior Pituitary
Posterior Pituitary
Thyroid Gland
Parathyroid Gland
Endocrine Pancreas
Adrenal Medulla
What are the hormones associated with the hypothalamus, ant. pituitary, post. pituitary, thyroid gland, parathyroid gland, endocrine pancreas, adrenal medulla
What are the steps of the hypothalamic- pituitary axis?
What is the hypothalamic- pituitary target endocrine organ feedback loop?
- Hypothalamus releases a hormone
- Hypothalamic hormones stimulate release of pituitary hormones
- Pituitary hormones stimulate targets to secrete more hormones
Hormones from final target organs inhibit release of anterior pituitary hormones
What does the hypothalamus release? What is its target organ?
Thyrotropin releasing hormone is released and acts on the anterior pituitary
What does the anterior pituitary release? What is its target organ?
Thyroid- stimulating hormone (Thyrotropin) acts on the thyroid gland
What does the thyroid gland release?
What is its target organ?
What is the target mechanism?
Thyroid hormones acts on target cells by stimulating or inhibiting the target cells