Physiology Chapther 18 Central Endocrine Glands 2 (TEST III)

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What do endocrine disorders result from?: 1) hyposecretion

2) hypersecretion

3) abnormal target responsiveness
"hyposecretion"?: too little
"hypersecretion"?: too much
What is one way of treating hyposecretion?: Give exogenous hormones.
Name 5 possible causes of hyposecretion?: 1) Genes, heredity
2) Dietary deficiency
3) Immunologic deficiency
4) Disease process
5) Medical interventions (toxins)
Distinguish between primary hyposecretion vs 2ndary?: primary = abnormal gland

2ndary= Deficiency of hormones Tropic Hormone

ex. anterior pituitary problem is 2ndary, pituitary problems is primary
Give 2 possible causes of hypersecretion?: 1) Tumors on endocrine gland, not subject to normal regulatory control

2) Immunologic factors: Antibodies may excessively stimulate a gland
Can a hypersecretion also be primary or secondary?: yes
The responsiveness of a target cell can vary by deliberately regulating what?: -the # of hormone-specific receptors
Describe Down Regulation?: effects target cell responsiveness
-it's a reduction in # of receptors as direct result of elevated hormone concentration
-it prevents target cells from overreacting to high hormone concentration
-target cells become desensitized to hormone, bc less receptors
Interacting hormones can affect what?: the target cell's responsiveness
Describe permissiveness?: -interacting hormone that affects target cell responsiveness
-one hormone must be present in sufficient amounts for the full effect of another hormone to occur
Give example of permissiveness?: for epinephrine to be fully effective thyroid hormone needs to be present
Describe synergism?: -interacting hormones that affect target cell responsiveness
-when several hormones complement each other and combine effects
-"1+1=5"
Give example of synergism?: sperm production
Describe antagonism?: -interacting hormones that affect target cell responsiveness
-one hormone causes a decrease in another hormone's receptors, therefore diminishing the effect of the other hormone
Circadian rhythms can effect what?: the concentration of hormones
What does SCN stand for?: suprachiasmatic nucleus
What is the SCN?: -master biological clock
-serves as pacemaker for body's circadian rhythms
Where is the SCN?: -cluster of cell bodies in hypothalamus above the optic chiasm
-where optic nerves cross in brain
What does the SCN secrete? where does is secret this to?: -"clock proteins"
-into cytosol
What do the clock proteins secreted by the SCN do?: -cyclic changes in their concentration change the neural output from the SCN
-Changes in the neural output produce cyclic changes in effector organs through the day
-self sustaining
-does not involve rods and cones
What occurs with self-starting genes?: -related to "clock proteins"
-turn themselves on
-concentration increases throughout the day
-after they reach critical pt they go back in nucleus and block further transcription of own production
-so level of protein gradually decreases
-as they degrade they remove inhibitory effector on nucleus and transcription of gene begins again
-self starting and self stopping
Describe structure of pineal gland?: -small, pine-cone shaped structure in brain
What hormone does the pineal gland secrete?: melatonin
Describe the pineal glands secretion of the hormone melatonin as it relates to circadian rhythms?: -helps keep the body's inherent circadian rhythms in synchrony with the light dark cycle
-melatonin increase up to 10 fold during darkness and decreases to low levels in light
Is the pineal gland (and it's hormone melatonin) the only signal involved in the timekeeping of the body?: -no
-other neural and blood-borne signals may be involved
Describe 4 other functions of the Pineal gland not related to circadian timekeeping?: 1) induces natural sleep without side effects of sedatives
2) inhibits hormones that stimulate reproductive activity
3) effective antioxidant, helping eliminate biologically damaging free radicals (so may slow aging process by removing free radicals) (at least in vitro)
4) appears to enhance immunity, reducing age-related shrinkage of thymus (which is the source of T cells)
What is the source of T cells?: the thymus
What is the pituitary gland?: -a very key endocrine gland
-produces a lot of hormone
-small structure at the base of the brain
The pituitary gland is AKA?: hypophisis
How many lobes does the pituitary gland have? Name them.: -Two
-Posterior lobe (neurohypophysis)
-Anterior lobe
(adenohypophysis)
The Posterior lobe of the pit. gl. is AKA?: Neurohypophysis
The Anterior lobe of the pit. gl. is aka?: adenohypophysis
The posterior lobe is composed of what?: nervous tissue
the anterior lobe of the pit. gl. is what kind of tissue?: glandular tissue
the suffix adeno means what?: gland
The posterior lobe of the pit. gl. acts as a unit with what?: the hypothalamus
The posterior lobe of pit. gl. has what kind of control?: neuro
What does the posterior lobe secrete?: -2 hormones
-vasopressin
-oxytocin
Describe vasopressin?: -produced by hypothal., secreted by posterior lobe of pit. gl.
-causes blood vessel constriction
-prevents excessive urination
When does the hypothal. produce vasopressin?: -When it detects to much of a solute concentration in the plasma
-so vasopress. prevents urination
-this increases H2O vol.
-this dilutes the solute molecules
Vasopressin is aka?: -ADH
-antidiuretic hormone
Describe oxytocin?: -produced by hypothal.
-secreted by post. lobe of pit. gl.
-stimulates uterine contraction and milk ejection
Vasopressin and Oxytocin are produced by what? Where are they stored?: Both produced by hypothal. neurons BUT stored in neuron terminals in the post. lobe of pit. gl.
How are the pit. and hypothal. connected?: by a neurolink
The posterior lobe of the pit. gl. could be viewed as an extension of what?: the hypothal.
The posterior lobe of the pit. does not make what?: hormones, just stores/secretes the ones made by the hypothal.
Professor Goldman considers the posterior lobe of the pit. gl. and the hypothal. to secrete what?: neurohormones
The anterior pit. is aka what? How many hormones does it secrete?: -adenohypohysis
-6
The anterior pit. is ? not ?.: glandular, nervous tissue
unlike the posterior pit., the anterior pit. does what?: -synthesizes its own hormones
-and secretes them
What does the vascular network within the hypothal. allow?: allows each anterior pit. hormone to be secreted thru signaling by a releasing hormone from this region of the brain
Many anterior pit. hormones can be considered what?: Tropic
-they regulate secretion of another gland
List the six hormones produced by the ant. pit.: 1) Thyroid-stim. hormone
-TSH
2) Adrenocorticotropic hormone
-ACTH
3)Follicle-Stimulating Hormone
-FSH
4) Luteinizing Hormone
-LH
5) Growth Hormone
-GH
6)Prolactin
Which of the 6 hormones produced by anterior pit. are not tropic?: only prolactin
What is TSH tropic for?: thyroid
What is ACTH tropic for?: tropic for adrenal CORTEX
What is FSH tropic for?: follicle glands
What is LH tropic for?: corpus lutein
Growth hormone is aka?: -GH
-somatropin
What does GH regulate?: -she considers it tropic
-regulates overall body growth
-important in intermediary metabolism
-debate over w/r tropic or not because it stimulates liver and liver is not a gland
What does the thyroid stim. hormone do?: Stimulates the secretion and growth of the thyroid gland
thyroid-stim. hormone is aka?: -TSH
-thyrotropin
What does the adrenocorticotropic hormone do?: -stimulates the growth and secretion of hormones from the adrenal cortex.
adrenocorticotropic hormone is aka?: -ACTH
-adrenocorticotropin
What does the follicle-stim. hormone do?: stimulates growth and dev. of ovarian follicles and sperm production
What does luteinizing hormone do?: -stimulates ovulation and luteinization (female)
-stimulates testosterone secretion (male)
What does prolactin do?: enhances breast development in women
Many of the anterior pit. hormones not only stim. endocrine glands but also do what?: they also have nonendocrine target cells
Map the path of TSH?: -released by ant. pit.
-stim.s thyroid gland
-thyroid gl. releases thyroid hormones (t3 and t4)
-effects metabolic rate
Map the path of ACTH?: -released by ant. pit.
-stim.s adrenal cortex
-adrenal cortex produces cortisol
-effects metabolic actions, stress response
Map the path of prolactin?: -released by ant. pit.
-stimulates mammary glands
-causes breast growth and milk secretion
Map the path of LH?: -released by ant. pit.
-acts on gonads
-stim.s sex hormone secretion
Map the path of FSH?: -released by ant. pit.
-stim.s gonads
-causes gamete production
Map growth hormone?: -released by ant. pit.
-acts on liver -acts on many other tissues where it directly produces metabolic actions
-liver releases somatomedins
-somatomedins stim. both bone and soft tissues growth
The hypothal. releases a lot of what?: hormones
The hypothal. has a chain of command with what?: the pituitary
The hypothalamus is involved in what kind of functions?: homeostatic
What 2 kinds of hormone released by the hypothalamus regulate the ANTERIOR pit.s hormone secretion?: releasing and inhibiting hormones
List the seven different hormones released by the hypothal. to reg. the hormone secretion of the anterior pit.: 1) TRH: stim.s release of TSH
2) CRH: stim.s ACTH
3) GnRH: stim.s FSH and LH
4) GHRH: stim.s growth hormone
5) GHIH: inhibits the release of growth hormone and TSH
6) PRH: stim.s prolactin
7) PIH: inhibits prolactin
What is TRH?: thyrotrophin-releasing hormone
-released by hypothal. to stim release of TSH from ant. pit.
What is CRH?: -corticotropin-releasing hormone
-released by hypothal. to stim. release of ACTH from ant pit.
What is GnRH?: -Gonadotropin-Releasing hormone
-Stimulates release of FSH and LH from ant. pit.
What is GHRH?: -Growth hormone releasing hormone
-releasedy by hypothal. to stim. release of growth hormone from ant. pit.
What is GHIH?: -Growth Hormone Inhibiting Hormone
-Inhibits release of growth hormone and TSH from ant. pit.
What is PRH?: Prolactin-Releasing Hormone
-from hypothal. to stim. release of prolactin from ant. pit.
What is PIH?: -Prolactin Inhibiting Hormone
-released from hypothal. to inhibit release of prolactin from ant. pit.
Explain why the Hypothalamic hormones could be considered to have a 3-hormone chain of command?: 1) hormone is released by hypothal. and then stim.s ant. pit.
2) another hormone is then released by ant. pit. and acts on target endocrine gland (remember tropic)
3) the target gland then releases 3rd hormone which stim.s target cell and produces physiologic effect
Many hypothalamic hormones have what?: more than one effect
A single ant. pit. hormone may be regulated by what?: 2 or more hypothalamic hormones
When a single ant. pit. hormone is regulated by 2 or more hypothalamic hormones what does the rate of secretion depend on?: the rate of secretion in response to two or more signals depends upon concentration of signals and intensity of other regulatory input
Many of the hormonal chemical messengers inv. in hypothal-pit. system are also produced where? Give example.: -produced in many other areas of the brain
-just given different name because of location and action
-ex. PIH (inh. prolactin inhibitory hormone) is structurally identical to dopamine
How do the hypothalamic regulatory hormones reach the ant. pit.?: -by the hypothalamic-hypophyseal portal system
-a vascular link
-a capillary to capillary connection
-blood in this system carries signals
-hypothalamic hormones are delivered DIRECTLY and at HIGH CONCENTRATIONS
-DIRECT ACCESS
-QUICK COMMUNICATION
The control of hypothalamic hormones could be called what kind of feedback?: -negative feedback
How well understood is the regulation of the hypothalamic hormones?: not well understood
Target gland hormones inh. hypothalamic and ant. pit. hormone secretion via what?give example.: negative feedback
-ex. a rise in cortisol from the adrenal cortex (target gland) can feedback and reduce CRH secretion (hypothal.) and the sensitivity of the ACTH secreting cells (ant pit.) to CRH
-ex. if cortisol falls in the blood then the other responses is reversed
The biological clock is what kind of loop?: Negative feedback loop
Concerning Endocrine control of growth, what is growth signaled by?: GH, BUT GH is NOT the sole factor
What factors influence growth?: -growth hormone (GH)
-genetics
-adequate diet
-freedom from chronic diseases
-normal levels of other growth-influencing hormones
What is permissiveness? give ex.: the idea of hormones needing to be present for other hormones to do it's job
-ex. GH needs thyroid hormone
Does GH play a role in fetal development?: -NO
-Placental fx does
Name the two rapid growth periods and influences over them?: 1) Postnatal growth spurt
-GH plays a role
2) Pubertal growth spurt
-GH may play a role, don't know
-ANDROGENS (ex. testosterone) DO contribute
3 metabolic effects of GH?: 1) Mobilizes fat stores as a major energy source
2) Increases blood glucose levels by decreasing glucose uptake by cells
3) Promotes growth in soft tissues and skeleton
When may GH be utilized?: When energy is needed and glucose is not sufficient
Why does GH sometimes increase blood glucose levels by decreasing glucose uptake by muscles?: -conserves glucose for glucose-dependent tissues (such as brain)
-important for maintaining body during prolonged fasting or times when body's energy needs exceed glucose stores
3 ways that GH promotes growth in soft tissues and skeleton?: 1) By signaling an increase in the # of cells (hyperplasia) and size (hypertrophy)
2) Stimulates cell division and prevents apoptosis (cell #)...so cell # increases
3) stim.s the uptake of AAs and protein synthesis in target cells (cell size)
What is the term for increase in # of cells?: hyperplasia
What is the term for increase in size of a cell?: hypertrophy
What is apoptosis?: controlled cell death...normal
Bone is what kind of tissue?: connective
Generally, what is bone tissue made of?: -cells and extracellular organic matrix
-collagen fibers in mucopolysaccharide-rich semisolid gel, the GROUND SUBSTANCE
What are osteoblasts?: -cells that produce the organic matrix (ground st.) in bones
What makes bones hard?: The precipitation of Calcium within the organic matrix (ground st.)
What distinguishes cartilage from bone?: cartilage is not calcified
What is a diaphysis?: The long thin part of a bone shaft
What is a epiphysis?: The flared, articulating knob at the end of long bone
What part of the bone is responsible for growth?: the epiphyseal plate
-this is a layer of cartilage separating the diapysis from the epiphysis
GH stimulates growth in what of the bone?: the length and thickness
GH stim.s what at the epiphyseal plate?: the LENGTHENING of the bone
-by stim. osteoblasts activity and the proliferation of epiphyseal cartilage
-new bone tissue replaces cartilage in the region
How does GH stim. bone thickness?: -by activating osteoblasts under the periosteum (which surrounds the whole bone)
Could GH be considered Tropic?: Yes
How does Growth Hormone exert it's effects?: -INDIRECTLY (tropic) by stimulating somatomedins, also called insulin-like growth factors
Somatomedins could also be called what?: Insuline-like Growth Factors
-somatomedins is a general term
How many somatomedins are identified? Name them.: -2
1) IGF 1
2) IGF 2
Describe IGF 1?: -a somatomedin
-stimulated by GH
-Mediates most of the growth-promoting effects of GH
Main source of IGF 1?: it is produced by the liver
IGF 1 production depends upon what?: adequate nutrition and it is also age dependent
Describe IGF 2?: -production is not dependent upon GH
-important in fetal development
Is IGF 1 or 2 GH dependent?: IGF 1 is
Secretion of GH is regulated by what?: GHRH & GHIH
Name six factors that influence GH secretion?: 1. Diurnal rhythym
2. Exercise
3. Hypoglycemia
4 Increased blood AAs
5. Stress
6. Decreased blood fatty acids
How does diurnal rhythm effect GH?: GH increases one hour after sleep
How does exercise effect GH: increases GH
How does hypoglycemia effect GH?: increases GH
How does hypoglycemia effect glucose?: decreases glucose
How does an increase in blood AAs effect GH?: increases GH
How does an increase in stress in adults effect GH: increases GH
How does decreased blood fatty acids effect GH?: increases GH
GH is the most ? hormone.: abundant
GHs only effect is on growth: -no, has many effects
Is it clear how GHRH and GHIH work?: NO
The only certainty in the cycle of GH is what?: That exercise, stress, decreased bl. glucose, inc. bl. AA, and decreased fatty acids effects it.
Trace hypothesized steps of GH chain: 1. one of the 6 factors inf.s it
2. depending on diurnal rhythm Hypothal. releases either GHIH or GHRH
3. These hormones either inh. or encourage the release of GH from the anterior pituitary
4. GH takes one of two routes:
a) to liver where it causes release of somatomedins
b) or it directly effects metabolic actions unrelated to growth
What kind of actions do somatomedins have?: -growth promoting actions
1) increase cell division
2) increase protein synthesis (decrease bl. AAs)
3) increase bone growth
What are some metabolic actions (unrelated to growth) the GH has?: 1. increases fat breakdown
2. increases blood fatty acids
3. decreases glucose uptake by muscles
4. increases blood glucose
GH associated abnormalities are generally effected by what?: either a deficiency or excess of GH
In childhood, what does GH hyposecretion cause?: dwarfism
What is Laron dwarfism?: Occurs when GH is produced BUT tissues don't respond b/c of RECEPTOR failure
-so they actually have excessive GH b/c it is not being used
What causes pygmies?: A lack of somatomedins, (the intermedians produced by the liver, IGF 1)
What does hyposecretion of GH in adults cause?: -reduced muscle mass
-b/c GH used for protein synthesis
To help in cases of GH deficiency what could you do? What is the exception?: -you could give exogenous hormone BUT doesn't work with tissue failure (b/c that is a receptor issue)
What does childhood hypersecretion of GH cause?: Gigantism
very rare
What is acromegaly?: -occurs when there is hypersecretion of GH after epiphyseal plates have closed
-bony material deposits on extremities
-most obvious on hands, feet, jaws, and cheekbone
-also occurs with excess exogenous GH (athletes)
Besides GH, what other hormones are essential for normal growth?: 1. TH
2. Insulin
3. Androgens
What essential role does TH play in normal growth?: -PERMISSIVE role in skeletal growth
What essential role does insulin play in normal growth?: a growth promoter
What essential role do Androgens play in normal growth?: -role in pubertal gr. spurt
-protein synthesis
You will not see the full effects of GH unless what is present: 1. TH
2. Insulin
3. Androgens

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