Module 1 Flashcards
What are the main functions of the endocrine system?
Homeostasis, Storage and utilization of energy substrates, Growth, Development, Reproduction, Response to environmental stimuli
What is the response of the nervous system relative to the endocrine system?
The endocrine system has slower responses but prolonged and more diffuse and longer lasting
What are the primary organs of the endocrine system?
Hypothalamus, Pituitary gland, Thyroid Gland, Parathyroid Glands, Adrenal Glands, Pacreas, Gonads, Placenta, Hormones and hormone like substances are also produced in other organs.
Define Endocrine Gland
Ductless gland that secrete hormones into blood stream
Define Target Organs
The organ that contains cells with receptors that have hormone specific receptors
Define Hormone
chemical messengers released by one cell to communicate with others
T/F A single hormone can facilitate multiple effects on different target tissue?
T. Different receptors will mediate different responses.
T/F a single physiological function can not be regulated by the sum of multiple hormones
F. A single physiological function can be regulated by the sum of multiple hormones. ex. BP is influenced by ADH, aldosterone, epinephrine etc…
Define Endocrine signaling
Transmitters are released into the bloodstream
Define Paracrine signaling
Released by a cell but doesn’t go too far in the blood stream, talks to nearby tissue
Define Autocrine Signaling
Mechanism from cell to talk to itself
Define Intracrine signaling
Can be same as autocrine - but is also the cell talking to itself and never sending the message out.
What is the most common form of regulation in hormone secretion?
Negative feedback
Define negative feedback and provide an example
Hormone actions directly, or indirectly inhibit further release of hormone. Ex; Insulin released…blood glucose decrease..the decrease on blood glucose inhibits further insulin release
Which hormones are lipid soluble?
Steroid and thyroid hormones
Which hormones are water soluble?
Most hormones, GH, PTH etc (if water soluble they will need a transporter)
Where are hormone receptors located?
The cell membrane or within the cell itself
T/F Receptors are a fixed quantity, there is not much hormone receptor fluctuation allowing for more consistency.
F. Receptors are not fixed. There is continuous receptor turnover.
healthy receptors are adapting to make physiology _____efficient.
More efficient
unhealthy receptors are adapting to make phisiology _____ Efficient
Less
Define Up regulation
Any situation where the cell responds by either increasing the number or the sensitivity to the hormone. Either way the net result in an increased sesitivity.
Define Down Regulation
Cells start to adapt and the number of receptors or sensitivity of receptors is decreased. Net result is a decreased sensitivity to that hormone
What is the process of Primary messenger hormones in signal transduction
Primary messenger mechanism is for FAT Soluble Hormones. The hormone is the actual messenger to initiate intracellular response.
What is the process of secondary messenger hormones in signal transduction
Mechanism for Water soluble hormones. Hormone is first messenger which in-turn activates a secondary messenger inside the cell to initiate intracellular response
What is the mechanism used for lipophilic (fat soluble) hormones?
Primary messenger signaling
What is the mechanism for hydrophilic (water soluble) hormones?
Secondary messenger signaling
What is the job of the hypothalamic system?
connects the CNS to the endocrine system. Junction between action potential of CNS and chemical reactions in the body.
What is released at the anterior pituitary? What is the pathway here?
Hypothalamus released pituitary releasing hormones these descend through hypophyseal portal system (capillaries in the hypothalamus communicate with pituitary capillaries before entering venous system.) Hormones from the hypothalamus then either stimulate or inhibit release of pituitary hormones.
What does the posterior pituitary do?
Extension of the hypothalamus that extends from the CNS to endocrine system.
What part of the brain functions to link the CNS to the endocrine system?
Hypothalamus
Where is the hypothalamus located?
The diencephalon of CNS.
What is the function of the hypothalamus?
junction box for the equilibrium of our system between the CNS and endocrine
What hormones are released from hypothalamus and control anterior pituitary gland?
TRS, GnRH, Somatastatin, Growth releasing hormone, corticotropin release hormone, substance P, Dopamine, Prolactin releasing factor.
What does GnRH (gonadatropin releasing hormone) stimulate?
Release of LH from anterior pituitary, and FSH from anterior pituitary
What does Somatostatin (SRIF) inhibit?
Release of GH (somatotropin) and TSH from anterior pituitary
What does GHRH (growth hormone releasing hormone) stimulate?
Release of GH from anterior pituitary
What does CRH (corticotropin releasing hormone) stimulate?
ACTH and B-endorphin from anterior pituitary
What does Substance-P inhibit?
ACTH - from anterior pituitary
What does Substance-P stimulate?
GH, FSH, LH and prolactin
What does Dopamine inhibit?
Synthesis/release of prolactin
What does PRF (Prolacting releasing factor) stimulate?
Release of prolactin from anterior pituitary
What Hormones are synthesized in the nuclei of the hypothalamus and decide to posterior pituitary gland?
ADH and Oxytocin (no step of releasing hormone-because it is direct)
anterior pituitary is also known as the ________
Adenohypophysis
What gland is considered the “master gland”
The pituitary gland
What are the three regions of the pituitary gland?
Median eminence, Infundibular stem, Infundibular process
Posterior pituitary is known as the __________
Neurohypophysis
What does the pituitary regulate?
Regulate growth, metabolism, reproduction, lactation, fluid balance and response to stress.
The neural cell bodies are located in the _________ _______
hypothalmic nuclei
What do the neural cell bodies do?
synthesize hormones
What is the path of a hormone in the pituitary gland?
- Neural cell bodies synthesize hormones
- Hormones are transported down the neural axon to the posterior pituitary gland
- terminal neural axon releases hormones from the post pituitary gland
What is the function of Oxytocin the female body?
Stimulates “let down” milk,
Stimulates uterine contraction
What is the function of oxytocin in the male body?
Suggestion that oxytocin might have a role in sperm motiliy
What is the target tissue for oxytocin?
Mammary gland (lactation), and the Uterus (pregnancy_
t/f Oxytocin receptors in uterus are down regulated in pregnancy
F large up regulation occurs during pregnancy
Where is Oxytocin released from and what effect does it have?
Posterior pituitary : distention of cervix, breast stimulation (lactation), and emotional stimuli
What are the 2 stimuli for oxytocin in breast feeding?
Breast stimulation and Positive emotional response
What feedback cycle is responsible for the release of oxytocin from the posterior pituitary?
- Positive feedback system
What inhibits oxytocin release?
- Stopping nursing
2. Negative emotional factors
What is the function of ADH?
monitor blood volume: ADH increases blood volume which decreases osmolarity and increases blood pressure.
define osmolarity
Amount of solute (electrolytes) per liter of solvent (plasma)
What is the target tissue for ADH
Kidney
What effect does ADH have on the kidney?
Tells kidney to “Hold on to water” effects the permeability of the tubule walls.
What effect does ADH have on vascular smooth muscle?
Promotes vasoconstriction to assist in elevating BP. only occurs at excessive non-physiological levels. ADH is a Vasopressin
What stimulates the release of ADH from the posterior pituitary?
Concentration: Increased plasma osmolarity
Blood pressure: decreased blood volume stimulates ADH , AND Angiotensin II indirectly promotes ADH release
Also-steress, trauma, exercise, heat, drugs, nicotine, morphine
ADH release is most sensitive to ______ ?
Osmolality (concentration): 1% change in osmolality will stimulate release of ADH.
What does circulating Angiotensin II do?
Increases the sensitivity of osmoreceptors in hypothalamus
stimulates thirst centers in hypothalamus
What inhibits the release of ADH?
- decreased plasma osmolality: Negative feedback loop/mechanism of control
- Increased blood volume/pressure-Negative feedback loop/mechanism of control
- Alcohol and caffeine
Define Diabetes Insipidus
Too little or ineffective ADH
What are the two types of DI?
Central-effects the CNS (pituitary tumor, TBI, ischemia) Most common
Nephrogenic-inability of the kidney to respond to ADH-kidney dz drugs damage to distal nephron
What are the signs/symptoms of DI?
Polyuria, Polydipsia
define hypervolemia
Excessive ADH release causes water reabsorption in collecting duct
Hervolemia facilitates ________
hyponatremia decreased sodium valiues in blood stream.
Define SIADH
Elevated ADH secretion results in excessive water reabsorption in kidney
Define natriuresis
Excessive sodium excretion
What is the result of elevated ADH?
Excess water reabsorption-Hypervolemia-hyponatremia-Natriuresis
What is the etiology of SIADH?
tumors, head injuries, meningitis, bronchiogenictmors and diabetes mellitus
What are the three layers of the Anterior pituitary?
- Pars Distalis-forms most of the anterior pituitary gland
- Pars tubularis - thin layer of cells that wrap around anterior/lateral infundibular stem
- Pars intermedia - small layer of cells locate between pars distills and pars nervosa
Which layer of the anterior pituitary disappears in adulthood?
the Pars intermedia
Anterior pituitary hormone release is regulated by the ________ ________ ______ ________.
Hypothalmic-hypophyseal portal system
Function of Prolactin
similar to growth hormone:
- breast development during puberty and pregnancy
- Stimulates milk production after birth (lactogenesis)
- inhibits ovulation
What is the target tissue for prolactin?
Mammary glands during puberty, pregnancy and while lactating new born
What other hormones are involved in puberty and breast development? and what do they all as a group inhibit
GH, estrogen, progesterone, thyroid releasing hormone, together inhibit release of dopamine (which is the inhibitory hormone for prolactin)
What stimulates prolactin release?
Pregnancy, Lactation, Miscellaneious (sleep dopamine antagonists)
What inhibits prolactin release?
dopamine (PIH), Dopamine agonists, discontinuation of stimuli
When does GH secretion peak?
adolescence
What is the function of GH?
works synergistially with IGF-1 (insulin growth factor).
Promotes growth of tissues and regulates metabolism to facilitate growth.
What is the target tissue of GH? (direct effect)
Liver, muscle, adipose
What is the indirect effect of GH?
Indirect effect on tissue via the IGF-1 pathway
What is the IGF-1 pathway?
- GH stimulates liver and liver produces/secretes IGF-1
- most IGF-1 produced in liver (some in many other tissues)
- IGF-1 levels peak at puberty and gradually decline with age.
What is the target tissue of IGF-1
Bone, cartilage, visceral organs
Actions of GH?
Anabolic: Liver-IGF synthesis/release and protein synth.
Metabolic: Adipose tissue: increased lipolysis, decrease glucose uptake
Metabolic: Muscle: Increased A.A. uptake/protein synthesis, and decreased glucose uptake
What does IGF-1 do in the cartilage?
Stimulates matrix growth/balance , amino acid uptake, DNA/RNA synthesis, critical for linear bone growth during development
What does IGF-1 do in the bone?
Facilitates osteoblast/osteoclastic activity
IGF-2 has a/n _____________ effect on tissue growth?
inhibitory
What do GH (direct) and IGF-1 (indirect) regulate?
Fat, carbohydrate and protein metabolism to facilitate growth.
How does GH and IGF-1 effect protein metabolism?
Stimulates amino acid uptake/synthesis and protein anabolism in tissue
How does GH and IGF1 effect carbohydrate metabolism?
Assits in maintaining blood glucose levels, impairs glucose uptake (opposite insulin), and stimulates liver glycogenolysis
How does GH and IGF1 effect fate metabolism?
Increases lipolysis, decreases glucose uptake into fat cell
Summarize IGF-1 and GH actions
- IGF1 and GH work synergistically to facilitate grwoth
2. IGF-2 balances the actions of IGF-1
What does IGF-1 inhibit?
GH release from pituitary
What does IGF-1 Stimulate?
Somatastatin (GH inhibiting factor) release from hypothalamus
What factors stimulate release of GH from anterior pituitary gland?
GHRH Elevated sex hormones Dietary protein, Hypoglycemia Stage 4 deep sleep Exercise
What factors inhibit GH release from anterior pituitary gland?
Somatatstin (GHIH) Glucocorticoids Hyperglycemia Negative feedback cycles Excessive androgen levels
What is the distinguishing factor between the 3 growth phases?
Phase 1 is prenatal and 1st year of growth
Phase 2 is juvenile growth and prior to puberty
Phase 3 is after puberty and is involved in adding sex hormones
What hormones influence growth?
GH Thyroid hormones Gonadal Steroid Hormones Insulin Cortisol (negative impact)
What are thyroid hormones necessary for in growth?
CNS development
What effect does Cortisol have on growth?
Negative impact-lytic effect on tissue
What is the clinical effect of insufficient GH? Excessive GH?
insuff:
1. Dwarfism (GH dysfunction before growth plates fuse)
Excess:
2. Gigantism (increase GH before eiphyseal plates close)
3. Acromegaly: increase in GH after epiphyseal plates close
What does TSH stimulate?
Synthesis and release of thyroid hormones (T3 and T4)
What does LH stimulate?
Female: stimulates ovaries,
Male: stimulates synthesis and secretion of testosterone
What does FSH stimulate?
Female: Stimulates the growth of ovarian follicles and estrogen secretion
Male: Stimulates sperm maturation in testicles
What does ACTH stimulate?
Stimulates synthesis and secretion of adrenal cortical hormones
What does MSH stimulate
stimulates melanin synthesis/release from melanocytes in skin (increases pigmentation)
