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Endocrine (updated 2016) > 02 Basic concepts > Flashcards

Flashcards in 02 Basic concepts Deck (29):

How is the endocrine system different from the nervous

endocrine is anatomically discontinuous

- major communications systems in the body
- integrate stimuli and responses to changes in external and internal environment
- crucial to coordinated functions of highly differentiated cells


How does the endocrine system broadcast hormonal messages

to all cells via secretion into blood and extracellular fluid

- slow and diffuse
- one gland potentially affects many or all body tissues


What are general principles of endocrine gland organization

Highly vascular
Functional secretory cells are usually epithelial


What are the three types of endocrine organ arrangements

- Discrete glands (thyroid)
- Endocrine components of other organs (pancreas, gonads, ovaries, testis)
- Scattered cells throughout other organs (C cells in thyroid)


What are some basic characteristics of hormones

May have more than one target
active in low concentrations
more than one hormone may affect a target
May have same actions in more than one tissue, or opposite actions in two tissues


What are the 3 classes of hormones

Amino acids


What are characteriestics and examples of steroid hormones

- originate from a cholesterol precursor
- organs: ovaries, testis, adrenal cortex
- lipid soluble; bind to receptors inside the target cell

mineralcorticoids, glucocorticoids, testosterone, and estradiol


What are characteriestics and examples of protein hormones

- name indicates chemical structure
- wide variety of molecule sizes
- organs: anterior pituitary, thyroid, parathyroid, pancreas
- NOT lipid soluble; bind to surface receptors of the target cell

Insulin, prolactin, ADH, oxytocin, and parathormone


What are characteristics and examples of amino acid hormones (analogues and derivatives)

- name indicates chemical structure
- organs: thyroid, adrenal medulla
- most not lipid soluble (exception thyroid); bind to receptors on the surface of target cell

tyrosine derivatives = catecholamines (dopamine, epinephrine, norepinephrine) & thyroid hormones (Thyroxine T4, Triiodothyronine T3)


How are steroid hormones produced/stored

produced on demand and not stored


What types of organelles do steroid producing cells have the most of

SER, golgi


Where are amino acids, peptides, glycoproteins and protein hormones stored


ex: insulin in pancreas


What types of organelle do protein hormone producing cells have high levels of



What type of cells do hormones have an affect on

target cells


Why do target cells respond to hormone

The cell has a receptor for the hormone


What are the two types of hormone receptors

Membrane receptors
Cytoplasmic receptors


What type of receptors do steroid hormones target

cytoplasmic/nuclear receptors


How does a steroid hormone change cell function

1) Bind to nuclear or cytoplasmic receptor
2) dimerizes
3) receptor hormone complex binds specific DNA sequences
4) Directly alters gene expression at the response element or promoter
5) produces a protein that elicits a biological response


How does hormonal action by plasma membrane receptors work

Hormone is 1st messenger
G proteins in cell membrane are activated
2nd messenger causes intracelluar change; may be cAMP, cGMP, Ca++

- used by hormones that cannot diffuse through the - -
plasma membrane: amines, peptides, proteins
- hormone does NOT directly alter gene expression


name the endocrine glands of animals (9)

pineal gland
pituitary gland
thyroid gland
parathyroid gland
adrenal gland


how does the nervous system send signals

- exerts point to point control through nerves
- electrical in nature
- fast


what are the principle functions of the endocrine system

- maintains homeostasis
- integrations and regulation of growth, metabolism, and development
- control, maintenance and instigation of sexual reproduction (including gametogenesis, fertilization, fetal growth, and development, and nourishment of the the newborn)


what are the 3 methods of cell communication between cells? Define them.

endocrine: hormone secreted into blood bonds distant target cells

paracrine: hormone acts locally by diffusing from its source to target cells in the neighborhood

autocrine: hormone acts on same cell that produced it


patterns of hormone secretion

some hormones secreted tonically (all the time); some secreted episodically (pulses)

frequency and amplitude of pulses vary in response to stimuli

diurnal (day, year, etc) and annual rhythms


what is the pattern of secretion of circulating cortisol

strong pulse at 8am
moderate pulses at 1pm, 8pm, 6am


what is the pattern of secretion of gonadotropin in males and females

varies over a lifespan
increases during fetal development
childhood FSH > LH
puberty slowly increasing
sinusoidal rhythm during adult reproductive period (LH > FSH)
greater increase in females as they age but both increase (FSH > LH)


what are the control mechanisms used to regulate hormones

external stimuli (fright, cold, light cues)
internal stimuli (blood sugar levels, hormonal signals from another gland)
feedback loops


what disease is an example of the critical importantance of receptors

Type II Diabetes
caused by a lack of response NOT lack of hormone


How does hormonal action through intracellular receptors work?

characteristic of steroid and thyroid hormones
steroid hormones diffuse through plasma membrane
bind to nuclear (or sometimes cytoplasmic) receptor
receptor-hormone complex binds specific DNA sequences
directly alters gene expression
new mRNA and proteins made
new proteins change cell function