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230 Cards in this Set
- Front
- Back
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Why is the endocrine system essential?
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Essential in maintaining homeostasis; coordinating body growth & development
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Compare the duration of hormonal stimulation vs. neural stimulation.
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Hormonal stimulation produces a slower & more prolonged response compared to neural stimulation
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can a cell have both neural and hormonal stimulation---simultaneously?
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YES
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secretory product of endocrine cells and organs; passes into circulation (& CT) for transport to target cells
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Hormone
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List the 3 mechanisms of hormonal control.
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Endocrine
Autocrine Paracrine |
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hormone released into circulation for transport to effector cells
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endocrine
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hormone released into CT where it diffuses to neighboring effector cells
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Paracrine
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hormone acts on cell that released it
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Autocrine
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List the 3 classes of hormones.
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Steroids: cholesterol-derived compounds
Small peptides, proteins and glycoproteins Amino acid analogues and derivatives |
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Where are Steroids: cholesterol-derived compounds hormones secreted/synthesized?
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Synthesized/secreted by ovaries, testes, and adrenal cortex
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_____________ are essential for steroid hormones to be transported in the blood.
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Carrier proteins
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Where are Small peptides, proteins and glycoprotein hormones produced?
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Produced: hypothalamus, pituitary gland, thyroid gland, parathyroid gland, pancreas, & enteroendocrine cells of GI tract/respiratory system
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Do Small peptides, proteins and glycoprotein hormones require carrier protiens to be transported in blood? If yes describe method, if not then describe method.
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NO.....they are dissolved in blood
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Which two classes of hormones are Amino acid analogues and derivatives?
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Catecholamines
Thyroid Hormones |
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What are the 2 catecholamines?
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Epinephrine
Norepinephrine |
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Where are Amino acid analogues and derivative hormones produced?
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Adrenal medulla
Thyroid gland Neurons |
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Do thyroid hormones require carrier proteins?
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Yes
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Do catecholamines require carrier proteins?
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NO
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What are the 2 types of receptors for horomones?
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Cell surface
Intracellular/nuclear |
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___________ and ____________ hormones interact with cell surface receptors. Why?
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Peptide hormones
Catecholamines They cannot cross cell membrane |
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Discuss the process of a peptide hormone or catecholamine binding to cell surface receptor and the end result.
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Hormone binds receptor receptor activation activation of mb-associated G proteins 2nd messenger production (cAMP; DAG; IP3; Ca2+) alter metabolism; produce hormone-specific response
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What type of hormones utilize nuclear receptors?
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steriods & thyroid hormones
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Why do steroid and thyroid hormones bind to nuclear receptors?
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They CAN cross cell membrane
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Discuss the composition of nuclear receptors.
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large multiprotein complexes of chaperons that contain 3 binding domains:
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What are the 3 domains of nuclear receptor chaperons?
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1)Hormone-binding domain
2)DNA-binding domain 3)N-terminal domain |
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What is the result of a hormone binding to a nuclear receptor?
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causes allosteric conformational change binding to DNA
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Steroid and thyroid hormones regulate the activity of ____________ and thus mRNA production.
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RNA polymerase
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Steroid and thyroid hormones directly regulate ___________.
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Gene expression
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___________ (general terms): Occurs when response to stimulus (hormone action) has effect on original stimulus (hormone-secreting cell)
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Regulation of Hormone Secretion by feedback mechanisms
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This type of feedback regulation has a response that decreases original stimulus (more common)
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Negative feedback
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This type of feedback regulation has a response that increases original stimulus (less common)
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Postitive feedback
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Which type of feedback regulation is the most common?
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Negative
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What is another name for pituitary gland?
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Hypophysis
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________ acts with the __________ as a master regulator of endocrine system.
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Pituitary
Hypothalamus |
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Where would you specifically find the pituitary gland?
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base of brain, lies in saddle-shaped depression of sphenoid bone, sella turcica
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What structures connect the pituitary to the hypothalamus?
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via infundibulum and a vascular network
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List the functional divisions of pituitary.
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Anterior lobe (adenohypophysis)
Posterior lobe (neurohypophysis) Pars nervosa |
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Which part of the pituitary gland is derived from evagination of ectoderm of oropharynx toward the brain (Rathke’s pouch)
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Anterior lobe/adenohypophysis
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What type of tissue would you find in the anterior pituitary?
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Glandular epithelium
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What type of tissue would you find in the neurohypophysis?
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Neurosecretory tissue
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Which brain ventricle is associated with the development of the Posterior pituitary?
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3rd ventricle
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What 3 structures make up the anterior pituitary?
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Pars distalis
Pars intermedia Pars Tuberalis |
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- thin remnant of posterior wall of pouch; next to pars distalis
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Pars intermedia
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The infundibulum is associated with the anterior/posterior pituitary?
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POSTERIOR
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The neurosecretory axons in the infundibulum form the ______________________________________________________________________________ tract.
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hypothalamohypophyseal tracts
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The blood supply of the pituitary gland stem from which 2 blood vessels?
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Inferior and Superior hypophyseal arteries
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____________ arises from internal carotid arteries & posterior communicating artery of circle of Willis; supplies – pars tuberalis, median eminence & infundibular stem
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Superior hypophyseal arteries
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______________arises from internal carotid arteries; supplies pars nervosa
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Inferior hypophyseal arteries
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Most of the anterior lobe of the pituitary gland has Direct/No Direct arterial supply.
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NO DIRECT
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Hypothalamohypophyseal portal system: Discuss it....SORRY
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1.Superior hypophyseal arteries primary (fenestrated) capillary plexus in infundibulum
2.Primary capillary plexus receives releasing & inhibitory hormones from neuroendocrine hypothalamohypophysiotropic nuclei 3.Primary capillary plexus drain into portal veins secondary capillary plexus (hypothalamohypophysial portal system) 4.Cells of pars distalis associate w/ secondary capillary plexus 5.Endocrine function of pars distalis directly regulated by hypothalamic releasing & inhibitory factors 6. Blood drains into sinus at base of diencephalon systemic circulation. 7. Some evidence blood flows via short portal veins from pars distalis to pars nervosa. 8. Blood from pars nervosa back toward hypothalamus, allowing hormones from anterior lobe to feedback directly to brain without making full circuit of systemic circulation. |
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Discuss the blood flow to the pars nervosa.
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: Inferior hypophysial artery capillary plexus in pars nervosa collects vasopressin & oxytocin
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Discuss the innervation of the posterior pituitary.
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1. Nerves enter infundibular stem & pars nervosa from the hypothalamic nuclei are components of posterior lobe of pituitary gland.
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Discuss the innervation of the anterior pituitary.
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Nerves entering anterior lobe are postganglionic fibers of ANS vasomotor function.
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Nerves entering anterior lobe are ____________ fibers of ANS
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postganglionic
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Hypothalamic signals stimulate the anterior pituitary to secrete ______ and _______ hormones.
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tropic
non-tropic |
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_____________hormones: regulate activity of cells in other endocrine glands
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tropic
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List the 4 tropic hormones.
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adrenocorticotropic hormone (ACTH); thyroid-stimulating hormone (TSH, thyrotropin); follicle-stimulating hormone (FSH); luteinizing hormone (LH)
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__________hormones: act directly on non-endocrine target organs
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non-tropic
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Important to distinguish between: Acidophils---lactotrops/somatotrops and Basophils---secrete tropic hormones
tricky stuff.....probably see this on test |
; )
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List the non-tropic hormones?
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growth hormone (GH); prolactin (PRL)
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ID three cells that compose the pars distalis....
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Acidophils
Basophils Chromophobes |
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Which cell type makes up the majority of the pars distalis?
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Chromophobes
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List the secretions of the chromophobe......huh...what are they....tell me.....i'm tired
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NOTHING....as far as we know
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What are the 2 subtypes of acidophils?
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Somatotropes
Lactotropes |
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What do somatotropes secrete?
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GH---growth hormone
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What do lactotropes secrete?
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Prolactin
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A lactotrope is what type of cell----basophil/acidophil/chromophobe?
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Acidophil
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Which cell in the pars distalis secretes tropic hormones?
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Basophils
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Which type of cell can be a somatotrope?
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Acidophil
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What effect does GHRF (growth hormone releasing factor) stimulate...cell and hormone?
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stimulates somatotropes (acidophils) to secrete GH
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What inhibits the secretion of GH from ____________?
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Somatostatin inhibits secretion of GH from somatotropes
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________, secreted by the stomach, inhibits the release of GH from acidophils/somatotropes.
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Ghrelin
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What symptoms would you expect from a tumor involving overstimulation of somatotropes?
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hypersecretion of GH....GIGANTISM in children and acromegaly in adults
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Decrease in secretion of GH in children results in _______.
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Dwarfism
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What do lactotropes secrete?
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Prolactin
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Lactotropes are a subtype of what type of cell? Where are they located?
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Acidophils in the pars distalis
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What does prolactin do?
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stimulates lactation post-partum
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_______ inhibits production of prolactin via __________ feedback.
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Dopamine
negative |
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Prolactin stimulates secretion of _________.
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Dopamine
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________ and _______ stimulate the lactotropes to secrete prolactin.
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Thyrotropin releasing hormone
VIP |
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_______________ undergo hypertrophy & hyperplasia during pregnancy & lactation
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Lactotropes
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Is pituitary size sex dependent?
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Yes......women have larger......if they have had kiddos
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List the secretions of Basophils.
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FLAT
FSH LH ACTH TSH |
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List the 3 different types of basophils.
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Corticotropes
Gonadotropes Thyrotropes |
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What do corticotropes secrete?
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POMC which is cleaved inside cell into:
1.ACTH (or corticotropin) 2.lipotrophic hormone (-LPH) 3.melanocyte-stimulating hormone (MSH) 4.enkephalin 5.-endorphin |
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____________ regulates secretion of ACTH, while ______ inhibits it.
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CRH (corticotropin releasing H)
Cortisol---inhibits |
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__________ maintains structure of adrenal gland & stimulates secretion of glucocorticoids & gonadocorticoids
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ACTH
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What do Gonadotropes secrete?
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FSH...follicle stimulating H
LH...leutenizing H |
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What regulates gonadotrope secretion?
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GnRH--gonadotropin releasing
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What do thyrotropes secrete?
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TSH
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______ regulates secretion of TSH by thyrotropes.
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TRH....from hypothalamus
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Pars intermedia surrounds the residual body of __________.
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Rathke's pouch
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What cells compose the pars intermedia?
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Parenchymal
Basophils Chromophobes |
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What is the function of the Pars Nervosa?
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A storage site for neurosecretions of neurons of hypothalamus
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Is Pars Nervosa an endocrine gland?
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NO...just storage
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Are the axons within the pars nervosa myelinated?
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NO
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Where/What do axons terminate in the pars nervosa?
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fenestrated capillary network of pars nervosa
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Found in pituitary; Specialized glial cell – supporting cell (contains glial fibrillary acidic protein)
Irregular in shape, with many branches; resemble astroglial cells; round/oval nuclei & lipofusion |
pituicyte
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What are the 3 sizes of vesicles present in the pars nervosa?
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10-30 nM
30 nM 50-80 nM |
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_______ is found in 10-30 nM
________ is found in 30 nM ________ is found in 50-80nM |
10-30 = oxytocin/ADH/neurophysin
30 = Ach 50-80 = Resemble dense core vesicles of adrenal medulla and adrenergic nerve endings |
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What is stored in herring bodies?
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Vasopressin/ADH
Oxytocin Neurophysin Ach |
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Large nonphysiologic doses of ADH/Vasopressin do what?
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raise BP
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How does ADH/Vasopressin raise BP?
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smooth mm constriction in small arteries and arterioles
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What is the primary physiologic effect of ADH/vasopressin?
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increase permeability of distal convoluted tubule of nephron and collecting ducts via ADH-regulated water channels
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What effect does ADH/vasopressin have on osmalality?
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increase
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___________ is a More potent promoter of smooth muscle contraction than ADH
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oxytocin
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The Primary effect of oxytocin is contraction of _____________________________.
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uterine smooth muscle & myoepithelial cells of mammary gland
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________ trigers release of oxytocin.
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Neuronal stimulation via hypothalamus
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Discuss feedback regulation in the pituitary gland.
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1.Product of target organ directly acts on cells of anterior lobe of pituitary gland
2.Product of target organ can also act directly on hypothalamus regulate secretion of hypothalamic releasing hormones 3.Allows very tight regulation of secretion from pituitary gland |
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Bi-lobed gland located in anterior neck region; consists of 2 lateral lobes connected by isthmus
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Thyroid
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Why is the thyroid a unique endocrine gland?
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stores large amounts of secretory product extracellularly
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constitutes nearly entire mass of gland; structural unit of thyroid gland
Spherical cyst-like compartment lined by simple cuboidal or low columnar epithelium (follicular epithelium) Contains colloid - gel-like substance |
Thyroid Follicle
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List the 2 types of cells that compose thyroid follicle.
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follicular
parafollicular |
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What are the hormonal secretions of thyroid follicular cells?
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T3 and T4
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What are the non-hormonal secretions of thyroid follicular cells?
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thyroglobulin
~iodine |
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What are the secretions of the thyroid parafollicular cells?
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Calcitonin
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What effect does Calcitonin have on blood calcium levels?
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lowers
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List the 3 hormonal secretions of the thyroid gland.
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Calcitonin
T3 T4 |
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_________ is a Physiologic antagonist to parathyroid hormone (PTH
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Calcitonin
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________ are inhibited by calcitonin. (cells)
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osteoclasts
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Calcitonin promotes _____________.
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calcium deposition in bone
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High blood Calcium with have what effect on calcitonin release?
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stimulates release of Calcitonin
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Is Calcitonin secretion regulated by pituitary/hypothalamus/neither?
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Neither
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_______ is Used to treat patients w/ hypercalcemia
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Calcitonin
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____________regulate cell & tissue basal metabolism; heat production; body growth & development
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T3 and T4
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________ regulates T3 and T4
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TSH.....via thyrotropes
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__________ is the major component of thyroid follicle colloid material.
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thyroglobulin
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large iodinated glycoprotein; an inactive storage form of thyroid hormones
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thyroglobulin
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Is thyroglobulin a hormone?
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NOOOOOOOOOOOOO
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List the 2 types of cells found in the parathyroid gland.
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Chief/principle
Oxyphil |
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What do chief cells secrete?
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PTH
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What do Oxyphil cells secrete?
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nothing
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Chief cells are functionally active in regulating fetal _________________.
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Ca2+ metabolism
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Why is PTH essential for life????what are the consequences of low calcium?
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death by tetany as calcium levels decrease
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What are the consequences of secreting PTH?
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increase in calcium
decrease in phosphate |
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High levels of calcium: _____PTH
Low levels of Calcium: ______PTH |
High = inhibit
Low = stimulates |
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Discuss the functions of PTH.
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1.Stimulates resorption of bone (osteoclasts) release of calcium & phosphate
2.decrease excretion of calcium (kidney) stimulating tubular reabsorption (of calcium). 3.increase urinary excretion of phosphate decrease phosphate levels in blood & extracellular fluids 4.Regulates conversion of vitamin D to an active form by stimulating activity of hydroxylase in kidney. 5.increase intestinal absorption of calcium |
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Discuss the Effect of PTH vs. calcitonin on blood calcium level
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PTH - slow, long-term homeostatic action on blood calcium levels; peak of increase blood calcium several hours after PTH secretion; calcitonin - decrease blood calcium within 1 hr of secretion
2.Calcitonin has a rapid, acute homeostatic action. |
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Endocrine 2 take a break
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Endocrine 2 take a break
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Where are the adrenal glands located?
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superior poles of kidneys embedded in adipose tissue
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Where are the adrenal glands in relation to the peritoneum?
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Retroperitineum
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What are the 2 histologic regions of the adrenal gland?
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Adrenal Cortex
Adrenal Medulla |
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Generally...what makes up the majority of the adrenal gland?
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Adrenal cortex makes up 80-90%
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What is the origin of adrenal cortical cells?
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Mesoderm Mesenchyme
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What is the origin of adrenal medulla cells?
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neural crest
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list the 3 arteries that supply the adrenal gland.
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A.Superior suprarenal arteries - from inferior phrenic arteries
B.Middle suprarenal arteries - from aorta C.Inferior suprarenal arteries - from renal arteries. |
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What are the 3 principal patterns of blood distribution in the adrenal gland?
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A.Capsular capillaries – supply capsule
B.Fenestrated cortical sinusoidal capillaries – supply cortex drain into fenestrated medullary capillary sinusoids C.Medullary arterioles – travel thru cortex w/in trabeculae; bring arterial blood to medullary capillary sinusoids |
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Adrenal medullary blood supply is distinct from the cortex in that it is considered___________.
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Dual blood supply
arterial and venous |
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Tunica media of adrenomedullary vein contains longitudinally arranged __________________.
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smooth muscle
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The adrenal cortex secretes steroids....are they stored before they are secreted?
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NO
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List the 3 concentric zones of the adrenal cortex.
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outside > in
Zona Glomerulosa Zona Fasciculata Zona Reticularis |
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The ________________ makes up 80% of adrenal cortical volume.
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Zona Fasciculata
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What is secreted in the zona glomerulosa?
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Aldosterone---primary product
deoxycorticosteron |
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What stimulates aldosterone secretion in the Zona Glomerulosa?
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angiotensin II and ACTH
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What is the function of mineralcorticoid hormones like aldosterone?
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fnx in controlling fluid & electrolyte levels
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List 3 location where aldosterone acts.
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1.Distal tubules of nephron (kidney) - stimulate absorption of Na+ & excretion of K+
2.Gastric mucosa – stimulate absorption of Na+ 3.Salivary & sweat glands – stimulate absorption of Na+ |
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Aldosterone stimulates absorption of ____ in Distal tubules of nephron (kidney, Gastric mucosa, and Salivary & sweat glands.
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Sodium
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Regulation of aldosterone secretion is managed through feedback via _______________________________________________.
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Feedback control by rennin-angiotensin-aldosterone system
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Discuss the Feedback control of aldosterone secretion by the rennin-angiotensin-aldosterone system.
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2.decrease BP or blood Na+ levels renin (from juxtaglomerular cells - kidney) converts angiotensinogen to angiotensin I travels to lungs angiotensin I converted to angiotensin II via angiotensin-converting enzyme (ACE) angiotensin II induces secretion of aldosterone by glomerulosa cells
3.decrease blood volume, BP and [Na+] inhibits release of renin from juxtaglomerular cells (kidney) |
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What type of capillaries are found between the cell columns of the Zona Fasciculata?
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Sinusoids
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What distinctive cytoplasmic feature is evident in Zona Fasciculata cells?
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Lipid droplets
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What do Zona fasciculata cell lipid droplets contain?
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neutral fats, fatty acids, cholesterol, and phospholipids
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What is secreted in the Zona Fasciculata?
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Cortisol--primary
corticosterone |
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Zona Fascuculata secretion of Cortisol is stimulated by ______.
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ACTH
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Glucocorticoids like cortisol, functions include ______________________________________________
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fnxs: control of carbohydrate, fat, and protein metabolism
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T/F: Zona Fasciculata secretes small amounts of Androgens
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TRUE
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What affect does cortisol have in the liver?
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2. Exerts anabolic effect in liver promotes uptake of fatty acids, amino acids, and carbohydrates glucose synthesis (gluconeogenesis) & glycogen polymerization (glycogenesis).
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In what tissues does cortisol have a catabolic effect?
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adipocytes
muscle circulating blood lymphatic system |
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Cortisol stimulates ___________ in adipose and ___________ in muscle.
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lipolysis
proteolysis |
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Cortisol limits ______________________________ in circulating blood.
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: inhibit macrophage and lymphocyte infiltration at sites of inflammation.
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What effect does cortisol have on the lymphatic system?
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induces atrophy of lymphatic system decreasing the circulating lymphocyte population.
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List the 2 glucocortcoids.
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Cortisol
corticosterone |
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Discuss the regulation of Glucocorticoids---cortisol.
|
Negative feedback
A.High levels of blood glucocorticoid inhibits secretion of corticotrophin-releasing hormone (CRH) from hypothalamus (negative feedback). B.decrease in CRH inhibits release of ACTH from corticotrophs of pars distalis of pituitary gland |
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What pigment appears and distinguishes cells of the Zona Reticularis?
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Lipofuscin
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What is secreted in the Zona Reticularis?
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A.major secretion - dehydroepiandrosterone (DHEA)
B.androstenedione C.may also secrete small amounts of glucocorticoids (cortisol) |
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_______ stimulates DHEA secretion in the Zona Fasciculata.
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ACTH
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_________ occurs to the Zona Reticularis following hypophysectomy
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Atrophy
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What are the 2 types of cells found in the adrenal medulla?
|
Adrenal Medullary cells
Ganglion cells |
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________ is another name for adrenal medullary cells.
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Chromaffin
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Which nervous system is associated with ganglion cells in the adrenal medulla?
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Sympathetic
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Medullary cells are modified ______.
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Neurons
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________ inhibits axonal growth of adrenal medullary cells.
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Glucocorticoids
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What do adrenal medullary cells secrete?
|
catecholamines: NE and Epi
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Is there one cell that secretes both NE and Epi or are there exclusive cells?
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Exclusive cells
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_________________________stimulates adrenal medullary cells to secrete catecholamines.
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stimulation by pre-synaptic
sympathetic splanchnic nerves |
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The Medulla functions as modified _________________ site of post-synaptic sympathetic cells that lack dendrites and axons
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sympathetic ganglion,
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Discuss the innervation of the adrenal medulla.
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1.Pre-synaptic sympathetic fibers (from splanchnic nerves) synapase on chromaffin cell releasing acetylcholine depolarizes medullary cell membrane Ca2+ enter the chromaffin cell exocytosis of epinephrine/norepinephrine
2.Emotional stimulus: secretion of norepinephrine predominates 3.Physiological (e.g. pain) stimulus: secretion of epinephrine predominates 4.In severe fear or stress: increases epinephrine “fight or flight” |
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Where does conversion of NE to Epi occur?
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In Chromaffin cells
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Discuss the process of converting NE to Epi.
|
1.Glucocorticoids from adrenal cortex enter medulla directly via cortical & medullary sinusoidal capillaries
2.Glucocorticoids induce expression of enzyme that catalyzes methylation of norepinephrine epinephrine 3.Epinephrine-containing cells more numerous in areas of medulla supplied w/blood from cortical sinusoids (therefore contains glucocorticoids) |
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Epinephrine controls _________________________________________ and regulates ______________________________.
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controls cardiac output; heart rate; regulates blood flow thru organs
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NE increases BP through ______________ and has a ____ half-life.
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increase BP via vasoconstriction; short half-life due to destruction in liver
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What is the function of the Pineal gland?
|
regulate body rhythms
|
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What regulates secretion/activity of the Pineal gland?
|
Secretions influenced by light and dark periods of day (photosensitive organ).
|
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What is the origin of the Pineal gland?
|
neuroectoderm
|
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What are the 2 products of the Pineal gland?
|
Melatonin
Seratonin |
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What are the 2 types of cells in the Pineal gland?
|
Pinealocytes
Glial Cells |
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______________ is the major distinguishing feature in the Pineal gland?
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Brain Sand
Corpora arenacea |
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What is the composition of brain sand?
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calcium phosphates and carbonates
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Discuss the innervation of Pineal Gland.
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NO BRAIN-DERIVED NERVE FIBERS
1.Innervated by post-synaptic sympathetic nerves from superior cervical ganglion 2.Myelin lost from axons as enter gland synapse on pinealocytes & release norepinephrine regulates production of melatonin 3.Serotonin is taken up by presynaptic axon terminals. |
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____________ is the major hormone of the Pineal gland.
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Melatonin
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Melatonin is synthesized from ____________.
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tryptophan
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Melatonin is inhibited by _____ and stiumulated by ______.
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inhibited = light
stimulated = dark |
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Regulates __________ function in mammals by inhibiting the steroidogenic activity of gonads (particularly the menstrual cycle)
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reproductive
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What does melatonin inhibit?
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neurosecretory neurons that produce GnRH in hypothalamus and thus inhibits FSH and LH in pituitary gland
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What symptoms occur with destruction of the pineal gland?
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Precocious...early puberty
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________________ is the emotional response to decreased day length during winter
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SAD seasonal affective disorder
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_____________ constitute the endocrine portion of the pancreas.
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islets of langerhans
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List the 5 types of cells found in the islet of langerhans.
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beta cells; alpha cells; delta cells; PP cells; G cells
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The majority of cells in the islets of langerhans are _____ cells.
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Beta
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What do pancreatic beta cells secrete?
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Insulin
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What do pancreatic alpha cells secrete?
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glucagon
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What affect does insulin have on blood glucose level? Glucagon?
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insulin decreases
glucagon increases |
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What do pancreatic delta cells secrete?
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somatostatin
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Discuss the paracrine and endocrine functions of the pancreatic delta cell.
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Paracrine function: inhibit hormone release
Endocrine function: reduces contractions of alimentary tract & gallbladder smooth muscle |
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what does the G in pancreatic G cell stand for?
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Gastrin
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What does gastrin do?
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stimulates HCl production
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What do PP/F cells secrete?
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pancreatic polypeptide
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Pancreatic polypeptide stimulate_______________ and inhibits ________________.
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A. Stimulates gastric chief cells
B. Inhibits bile secretion; intestinal motility; pancreatic enzyme secretion & HCO3 secretion |
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What do pancreatic D-1 cells secrete?
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VIP
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What do the pancreatic enteroendocrine cells secrete?
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Secretin
Motilin substance P |
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Insulin stimulates....
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a.Uptake of glucose from circulation via glucose transporters
b.Storage of glucose by activation of glycogen synthase & synthesis of glycogen. c.Phosphorylation and initiation of glycolysis degrade glucose d.Uptake of amino acids (may involve co-transport with glucose) e.Secretion by exocrine pancreas |
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Insulin inhibits....
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a.Lipase activity in adipose cells
b.Catabolism of protein |
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Glucagon stimulates.....
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A.Release of glucose into bloodstream
B.Synthesis of glucose (gluconeogenesis) C.Glucogenolysis (breakdown of glycogen) in the liver. D.Proteolysis to promote gluconeogenesis E.Fat mobilization from adipose cells F.Hepatic lipase |
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Glucagon inhibits....
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Inhibits secretion from exocrine pancreas
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Which pancreatic islet cells secrete somatostatin?
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Delta cells
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Discuss the regulation of insulin secretion.
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1.Normal blood glucose level 70 mg/100 ml
2.Blood glucose level > 70 mg/100ml stimulates secretion of insulin from cells. 3.increase in levels of fatty acids in blood, gastrin, CCK, and secretin also induce secretion of insulin. 4.Results in uptake and storage of glucose by liver and muscle 5.Removal of glucose from blood stops insulin secretion. |
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Discuss the regulation of glucagon secretion.
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1.Blood glucose level < 70 mg/100 ml stimulates secretion of glucagon.
2.Low levels of fatty acids in blood also stimulates release of glucagon from cells. 3.Blood glucose levels >> 70 mg/100 ml inhibit release of glucagon. 4.Insulin in general blood circulation inhibits release of glucagon. |
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Discuss the innervation of islets of langerhans.
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1.Both sympathetic & parasympathetic innervation
2.~10% of islet cells have nerve endings directly on plasma membrane 3.Autonomic nerves may have direct effects on hormone secretion by and cells 4.Parasympathetic stimulation secretion of both insulin and glucagon. 5.Sympathetic stimulation secretion of glucagon but INHIBITS secretion of insulin. 6.May contribute to availability of circulating glucose in stress reactions. |
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Discuss the blood supply of the islets of langerhans.
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1.Arterioles enter periphery of islets and branch into fenestrated capillaries.
2.Capillaries first perfuse and cells, before blood reaches cells. 3. Efferent capillaries exit islet and branch into capillary networks that surround acini of exocrine pancreas. 4. Resembles portal systems of other endocrine glands! |
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Finished
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Finished
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