Chapter 17- Endocrine system Flashcards
Endocrinology
study of structure and function of the endocrine glands and the
diagnosis and treatment of disorders of the endocrine system
Hormone
chemical messenger secreted by cells of an endocrine tissue/gland into the interstitial fluid that diffuses to the blood capillaries, is transported into the bloodstream to specific “target” cells, where it binds to a specific receptor and has an effect on that cell’s physiological activity
Endocrine Glands
pituitary, thyroid, parathyroid, adrenal and pineal glands
Organs with endocrine tissue
hypothalamus, thymus, pancreas, ovaries,
testes, kidneys, digestive tract, heart, adipose tissue and placenta
Tropic hormone
A tropic hormone is a hormone that tells another gland to make and release its own hormones. Think of it like a messenger or a boss that gives instructions to other glands in your body.
So, tropic hormones don’t directly do the job themselves—they signal other glands to get the job done!
Difference between endocrine tissue and gland
gland= directly produces hormone (pituitary)
endocrine tissue= some capacity to produce hormone but has other functions (hypothalamus)
Regulating physiology functions of hormones
-chemical composition of the ECF
-metabolism and energy balance
-biological clock
-contraction of smooth and cardiac muscle
-some immune system functions
Functions of hormones
-regulate many aspects of physiology
-control growth and development
-regulate the reproductive organs
Nervous system vs endocrine system mediator molecules
N= neurotransmitters
E= hormones
Nervous system vs endocrine system site of action
N= close to release site (synapse)
E= far away from release site (anywhere)
Nervous system vs endocrine system types of target cells
N= few cell types, neurons, muscle, glands
E= any body cells
Nervous system vs endocrine system time to onset of action
N= milliseconds
E= seconds to days
Nervous system vs endocrine system duration of action
N= shorter (msec)
E= longer (sec to days
Anterior pituitary physical characteristics
-sits within the sella turcica and sphenoid bone
-attached to the hypothalamus via the infundibulum
-under control of the hypothalamus
-largest portion
Releasing hormones from the hypothalamus
-gonadotropin-releasing hormone
-thyrotropin-releasing hormone
-corticotropin-releasing hormone
-prolactin-releasing hormone
-somatostatin/prolactin-inhibiting hormone
-growth hormone-releasing hormone
posterior pituitary hormones
-oxytocin
-antidiuretic hormone
-produced by neurons in the hypothalamus, stored on posterior, controlled release from neural response
histology of anterior pituitary
Grows upwards from primitive pharynx during embryological development, larger portion of pituitary gland
histology of posterior pituitary
- Grows downwards from the brain;
composed of nervous tissue - Stores hormones made by the
neurons in hypothalamus
7 anterior pituitary hormones
Prolactin (PRL)
Thyroid stimulating hormone (TSH)
Luteinizing hormone (LH)
Follicle-stimulating hormone (FSH)
Growth hormone (GH)
Adrenocorticotrophic hormone (ACTH)
Melanocyte-stimulating hormone (MSH)
Functions of GH-IGF action
1) Protein synthesis
- Tissue repair
2) Lipid metabolism
- Provides energy via fatty
acids + glycerol
- Spares protein
3) Carbohydrate metabolism
- Stimulates glucose
production by liver
4) Electrolyte balance
- Promotes Na+, K+, Cl-
retention by kidneys, increases
Ca2+ absorption by small
intestines
water soluble
-travel freely through blood stream
-no transport proteins
-catecholamines
-peptide hormones
-majority of hormones
lipid soluble
-need a transport protein to travel
-thyroid hormones
-Eicosanoids
-steroid hormones
tryptophan
is both water soluble and lipid soluble
-melatonin is derivative of tryptophan
examples of peptide hormones
-oxytocin
-insulin
-glucagon
-parathyroid hormone
-calcitonin
-erythropoietin
all peptide hormones are ________
water-soluble
all steroid hormones are __________
lipid-soluble
hormone synthesis example (steroids)
cortisol and aldosterone secreted by the adrenal cortex (outer portion of the adrenal gland)
hormonal
-most common secretion
-stimulate anterior pituitary gland to secrete hormones
-stimulates other endocrine glands to secrete hormones
humoral
-in response to blood/ECF levels
-capilarry blood contains low [] of Ca, stimulates secretion of PTH by parathyroid glands
Neural
-flight or fight
-preganglionic SNS fiber stimulates adrenal medulla cells
Up-regulation
cell produces more receptors (increased density) and increases its own sensitivity to a hormone
Down-regulation
cell produces less receptors (decreased density) and decrease its sensitivity to a hormone
how does peptide hormone (water-soluble) act
acts via a surface receptor on cell membrane and second messenger system
how does a steroid hormone (lipid-soluble) act
acts by diffusing into the nucleus and binding to a nuclear receptor associated with a gene
glycogenesis
synthesis of glycogen
glycogenolysis
breakdown of glycogen via hydrolysis (addition of water)
gluconeogenesis
synthesis of glucose from non-carbohydrates, especially fats and proteins (creation of new glucose)
classic signs and symptoms of diabetes mellitus
polyuria, polydipsia, polyphagia
further signs of DM based on blood/urine test
hyperglycimia, glucosuria, ketonuria, ketones
difference between endocrine and exocrine
exo= has a duct gland
endo= hormones secreted into ISF then diffused into blood capillaries
Type 1 DM
-genetic susceptibility
-environmental factors
-autoimmune factors
Type 2 DM
-genetic factors
-constitutional factors (obesity)
-decreased insulin secretion
-insulin resistence
hypoglycemic hormone
-decrease BG
-insulin, thyroid
hyperglycemic hormones
-increase BG
-glucagon
-human growth hormone
-cortisol
forms of chemical signalling, autocrine
a cell targets itself
stress 3 phases
- alarm= epi/norepinephrine
- resistance= cortisol, glucagon, ACTH, thyroid, AD, aldosterone, growth hormone
- exhaustion= depleted all resources, fatal w/o intervention
forms of chemical signalling, juxtacrine
a cell targets a cell connected by gap junctions
forms of chemical signalling, paracrine
a cell targets a nearby cell
forms of chemical signalling, endocrine
a cell targets a distant cell through bloodstream
eicosanoids
all derived from arachidonic acid
-leukotrienes
-prostacyclin
-thromboxanes
-prostaglandins
leukotrienes
synthesized due to the action of lipoxygenase on arachidonic acid
prostacyclin
inhibits blood clotting and vasoconstriction
thromboxanes
stimulate vasoconstriction and clotting
prostaglandins
promote fever and pain, promote ovulation, inhibit gastric secretion, promote blood circulation in kidney
