Endocrine System Flashcards
Hypothalamic-hypophyseal tract
Bundle of axons that runs through infundibulum and connects the posterior pituitary to the hypothalamus
Arises from neurons in paraventricular and supraoptic nuclei of hypothalamus
Glandular anterior lobe origin
Epithelial tissue
Anterior lobe and hypothalamus connection
No direct neural connection
Vascular connection 👍
-primary capillary plexus in infundibulum communicates inferiority via small hypophyseal portal veins with a secondary capillary plexus in anterior lobe
Hypophyseal portal system
Primary and secondary capillary plexuses + intervening hypophyseal portal veins
Arrangement of blood vessels in which a capillary bed feeds into veins which in turn feed into a second capillary bed
Hypophyseal portal system ensures…
That the min. Quantities of hormones released by the hypothalamus arrive rapidly at the anterior pituitary w/o being diluted by the systemic circulation
Paraventricular neurons (of hypothalamus) primarily make
Oxytocin
Supraoptic neurons (of hypothalamus) mainly produce..
Antidiuretic hormone (ADH)
Oxytocin
Peptide from neurons in paraventricular nucleus of hypothalamus
Oxytocin regulation of release
Stimulated by impulses from hypothalamic neurons in response to stretching of uterine cervix or suckling of infant at breast
Inhibited by lack of appropriate neural tissue
Oxytocin target organs and effects
Uterus: stimulates uterine contractions; initiates labor
Breast: initiates milk ejection
Antidiuretic hormone (ADH)
“Vasopressin”
Peptide
From neurons in supraoptic nucleus of hypothalamus
ADH Regulation of release
Stimulated by impulses from hypothalamic neurons in response to increased blood solutes concentration of decreased blood volume; also stimulated by pain, some drugs and low blood pressure
Inhibited by adequate hydration of the body and by alcohol
ADH Regulation of release
Stimulated by impulses from hypothalamic neurons in response to increased blood solutes concentration of decreased blood volume; also stimulated by pain, some drugs and low blood pressure
Inhibited by adequate hydration of the body and by alcohol
ADH target organs and effects
Kidneys: stimulate kidney tubule cells to reabsorb water from the forming urine back into blood
ADH target organs and effects
Kidneys: stimulate kidney tubule cells to reabsorb water from the forming urine back into blood
ADH effects of hypo-secretion and hyper-secretion
Hypo: diabetes insipidus (intense thirst and huge urine output)
Hyper: Syndrome of inappropriate ADH secretion (SIADH)
ADH effects of hypo-secretion and hyper-secretion
Hypo: diabetes insipidus (intense thirst and huge urine output)
Hyper: Syndrome of inappropriate ADH secretion (SIADH)
Tropic hormone
“Tropin”
Regulates secretory action of other endocrine glands
-TSH
-ACTH
-FSH
-LH
Tropic hormone
“Tropin”
Regulates secretory action of other endocrine glands
-TSH
-ACTH
-FSH
-LH
Growth Hormone (GH)
“Somatotropin”
Protein
Produced by Somatotropic cells of anterior lobe
Anabolic (tissue building) hormone
Has metabolic and growth-promoting actions
GH direct actions on metabolism
-metabolizes fats from fat depots for transport to cells, increasing blood levels of fatty acids and encouraging their use for fuel
-decreases rate of glucose uptake and metabolism, conserving glucose
-anti-insulin effect of GH
-increases amino acid uptake into cells and their incorporation into proteins
Anti-insulin effect of GH
In the liver, it encourages glycogen breakdown and release of glucose to the blood
Raises blood glucose levels
GH regulation of release
Stimulated by GHRH release, which is triggered by low blood levels of GH as well as by a # of secondary triggers including deep sleep, hypoglycemia, increases in blood levels of amino acids, low levels of fatty acids, exercise, and other types of stressors
Inhibited by feed back inhibition exerted by GH and insulin-like growth factors (IGFs), and by hyperglycemia, hyperlipidemia, obesity, and emotional deprivation via increased GHIH (somatostatin) or decreased GHRH release
GH effects of hyposecretion and hypersecretion
Hypo: pituitary dwarfism in children
Hyper: gigantism in children; acromegaly in adults
Thyroid-stimulating hormone (TSH)
“Thyrotropin”
Glycoprotein
Tropic hormone that stimulates normal development of thyroid gland
Thyrotropic cells
TSH regulation of release
Stimulated by TRH and in infants indirectly by cold temp
Inhibited by feedback inhibition exerted by thyroid hormones on anterior pituitary hypothalamus and by GHIH
TSH target organ and effects
Thyroid gland: stimulates thyroid gland to release thyroid hormones
TSH effects of hyposecretion and hypersectretion
Hypo: hypothyroidism, may cause myxedema
Hyper: effects similar to those of Graves’ disease (antibodies mimic TSH)
Adrenocorticotropic hormone (ACTH)
“Corticotropin”
Peptide
Secreted by corticotropic cells
It is split from prohormone (large precursor molecule) with pro-opiomelanocotrin (POMC)
Stimulates the adrenal cortex to release corticosteroid hormones
ACTH regulation of release
Stimulated by corticotropin-releasing hormone (CRH); stimuli that increase CRH release include: fever, hypoglycemia, and other stressors
Inhibited by feedback inhibition exerted by glucocorticoids (block secretion of CRH and ACTH release)
ACTH target organs and effects
Adrenal cortex: promotes release of glucorticoids and androgens (mineralocorticoids to a lesser extent)
ACTH Effects of hyposecretion and hypersecretion
Hypo: rare
Hyper: Cushing’s disease
Gonadotropins
Follicle-stimulating hormone (FSH) and luteinizing hormone (LH)
Regulate function of gonads
FSH stimulates production of gametes (sperm or egg)
LH promotes production of gonadal hormones
Almost absent from blood of prepubertal
During puberty, gonadotropic cells are activated and gonadotropin levels rise, causing gonad to mature
Follicle-stimulating hormone (FSH)
Glycoprotein
By gonadotropic cells
FSH regulation of release
Stimulated by gobadotropin-releasing hormone (GnRH)
Inhibited by feedback inhibition exerted by estrogens in females abdominal testosterone in males
FSH regulation of release
Stimulated by gobadotropin-releasing hormone (GnRH)
Inhibited by feedback inhibition exerted by inhibin, and estrogens in females and testosterone in males
FSH target organ and effects
Ovaries and testes
Females: stimulates ovarian follicle maturation and production of estrogens
Males: stimulates sperm production
FSH target organ and effects
Ovaries and testes
Females: stimulates ovarian follicle maturation and production of estrogens
Males: stimulates sperm production
FSH and LH effects of hyposecretion
Failure of sexual maturation
Luteinizing hormone (LH)
Chemical structure: Glycoprotein
Cell type: Gonadotropic cells
Luteinizing hormone (LH)
Chemical structure: Glycoprotein
Cell type: Gonadotropic cells
LH regulation of release
Stimulated by gonadotropin-releasing hormone (GnRH)
Inhibited by feedback inhibition exerted by estrogens and progesterone in females and testosterone in males
LH target organs and effects
Ovaries and testes
Females: triggers ovulation and stimulates ovarian production of estrogens and progesterone
Males: promotes testosterone production
Prolactin (PRL)
Chemical structure: protein
Cell type: prolactin cells
PRL target organ and effects
Breast secretory tissue: promotes lactation
PRL effects of hyposecretion and hypersecretion
Hypo: poor milk production in nursing women
Hyper: inappropriate milk production (galactorrhea); cessation of menses in female; impotence in males
What is the key difference between the way the hypothalamus communicates with the anterior pituitary and the way it communicates with the posterior pituitary?
Hypothalamus communicates with ANTERIOR pituitary via hormones releases into a special portal system of blood vessels
It communicates with posterior pituitary via action potentials traveling down axons that connect the hypothalamus to the posterior pituitary
Zoe drank too much alcohol one night and suffered from a headache and nausea the next morning. What caused these “hangover” effects?
Alcohol inhibits ADH secretion from the posterior pituitary and causes copious urine output and dehydration
Describe structural and functional relationships between the hypothalamus and pituitary gland.
The pituitary gland hangs from the base of the brain and is enclosed by bone. It consists of a hormone-producing glandular portion ( anterior pituitary/adenohypophysis) and a neural portion (posterior pituitary or neurohypophysis) which is an extension of hypothalamus. The neurohypophysis includes: infundibulum and posterior pituitary
Describe structural and functional relationships between the hypothalamus and pituitary gland.
The pituitary gland hangs from the base of the brain and is enclosed by bone. It consists of a hormone-producing glandular portion ( anterior pituitary/adenohypophysis) and a neural portion (posterior pituitary or neurohypophysis) which is an extension of hypothalamus. The neurohypophysis includes: infundibulum and posterior pituitary
Comparison of NS and ES
NS:
Initiates responses RAPIDLY
SHORT-Duration responses
Acts via APs and NEUROTRANSMITTERS
Acts as SPECIFIC LOCATIONS determined by axon pathways
Neurotransmitters act over very SHORT DISTANCES
ES:
Initiates responses SLOWLY
LONG-DURATION responses
Acts via HORMONES released into the blood
Acts as DIFFUSE LOCATIONS- targets can be anywhere blood reaches
Hormones act over LONG DISTANCES
Major process that hormones control and integrate
-reproduction
-growth and development
-maintaining electrolyte, water, and nutrient balance of the blood
-regulating cellular metabolism and energy balance
-mobilizing body defense
Endocrine glands
-ductless
-well-vascularized
-Release hormones directly into blood or lymph
-pituitary
-thyroid
-parathyroid
-adrenal
-pineal
Autocrine
Short-distance chemical signal that exert their effects on the same cells that secrete them
Ex. Prostaglandins released by smooth muscle cells cause this smooth muscle cells to contract
Hormones
Long-distance chemical signals that travel in blood or lymph throughout the body
Hormones
Long-distance chemical signals that travel in blood or lymph throughout the body
Paracrines
Short-distance chemical signals
Act locally (w/in the same tissue) but affect cell types other than those releasing the paracrine chemicals
Ex. Somatostatin released by one pop. of pancreatic cells inhibits the release of insulin by a different pop. If pancreatic cells
Steroid hormones
Lipid soluble
Amino acid-based hormones
Water soluble except thyroid hormone
Where in the cell are steroid hormones synthesized? Where are peptide hormones synthesized? Which of these 2 type of hormone could be stored in vesicles and released exocytosis?
(A)Steroid hormones are synthesized on the membrane of smooth ER
(B)Peptide hormones are synthesized on rough ER
(C)Peptide hormones
Corpus-
Body (corpus callosum)
Corpus-
Body (corpus callosum)
Describe the 2 major mechanisms by which hormones bring about their effects on their target tissues.
Cell-surface receptor activation: hormone binds to a receptor protein on outside of cell membrane, which then activates intracellular processes. Used by amino acid based- can’t pass through cell membrane
Intracellular receptor recognition: hormone enters the cell and binds to a receptor, which changes cell’s protein synthesis. Used by steroid hormones, slower b/c involves protein synthesis
Cell responses to hormone stimulation may involve changes in…
-Membrane permeability
-enzyme synthesis, activation, or inhibition
-secretory activity
-Mitosis
Cyclic AMP system: 2nd messenger mechanisms employing G proteins and intracellular messenger: amino acid-based hormones interacting with target cells
1) hormone brands to a plasma membrane receptor that couples to a G protein
2)G protein is activated, then it couples to adenylate cyclase, which catalyzes the synthesis of cyclic AMP from ATP
3)adenylate cyclase converts ATO to cAMP (2nd messenger)
4) cAMP activates protein kinases
5) cellular response
Steroid hormones (and thyroid hormones) effecting responses: intracellular receptors and direct gene activation
Enter their target cells and effect responses by activating DNA, which initial messenger RNA formation (transcription) leading to protein synthesis
Which class of hormones consists entirely of lipid-soluble hormones? Name the only hormone in the other chemical class that is lipid soluble.
Steroids are all lipid soluble. Thyroid hormones are the only amino acid-based hormones that are lipid soluble
Hurmoral stimulus
Hormone release caused by altered levels of certain crustal ions or nutrients
Ex.
Stimulus: low concentration of Ca2+ in capillary blood
Response: parathyroid glands secrete parathyroid hormone (PTH), which increases blood Ca2+
Neural Stimulus
Hormone release caused by neural input
Ex.
Stimulus: APs in rehanging sympathetic fiber to adrenal medulla
Response: Adrenal medulla cells secrete epi and norepinephrine
Hormonal Stimulus
Hormone release caused by another hormones (a tropic hormone)
Ex.
Stimulus: Hormones from hypothalamus
Response: Anterior pituitary gland secretes hormones that stimulate other endocrine glands to secrete hormones
Explain how hormone release in regulated
(-) feedback mechanism- some internal and external stimulus triggers hormone secretion. As levels of a hormone rise, it causes target organ effects, which then feedback to inhibit further hormone release. Result: blood levels of many hormones vary w/in narrow range
Blood levels of hormones reflect…
A balance between secretion and degradation/excretion.
Liver and kidneys- major degrade hormones; breakdown products are excreted in urine and feces
Permissiveness
Situation in which one hormone must be present in order for another hormone to exert its full effects
Synergism
Occurs when 2 or more hormones produce the same effects in a target cell and their results together are amplified
Antagonism
Occurs when a hormone opposes or reverses the effect of another hormone
Identify factors that influence activation of a target cell by a hormone
Bloody levels of hormone
Relative #s of receptors for the hormone on or in the target cells
Affinity (strength) of the binding between hormone and receptor
Up-regulation
Persistently low levels of a hormone can cause its target cells to form additional receptor for that hormone
Down-regulation
Prolonged exposure to high hormone concentrations can decrease the # of receptors for that hormone
Desensitizes the target cells, so they respond less vigorously to hormonal stimulation, preventing them from overreacting to persistently high hormone levels
Down-regulation
Prolonged exposure to high hormone concentrations can decrease the # of receptors for that hormone
Desensitizes the target cells, so they respond less vigorously to hormonal stimulation, preventing them from overreacting to persistently high hormone levels
Lipid-soluble hormones
Consist of: all steroid hormones and thyroid hormone
Sources: adrenal cortex, gonads, and thyroid gland
Stored in secretory vesicles: no
Transport in blood: bound to plasma in proteins
1/2 life in blood: long (most need to be metabolized by liver)
Location of receptors: usually inside cell
Mechanism of action at target cell: activate genes, causing synthesis of new proteins
Water-soluble hormones
Consist of: All amino acid-based hormones except thyroid hormone
Sources: all other endocrine glands
Stored in secretory vesicles: yes
Transport in blood: usually free in plasma
1/2 life in blood: short (most can be removed by kidneys)
Location of receptors: on plasma membrane
Mechanisms of action at target cell: usually act through 2nd messenger systems
Which type of hormone generally stays in blood longer following its secretion?
Lipid-soluble: long 1/2 life
Which type of hormone generally stays in blood longer following its secretion?
Lipid-soluble: long 1/2 life
Describe structural and functional relationships between the hypothalamus and pituitary gland
Pituitary gland is connected to your hypothalamus through a stalk of blood vessels and nerves. Through the stalk your hypothalamus communicates with the anterior pituitary lobe via hormones and posterior lobe through nerve impulses
Discuss the structure of the posterior pituitary, and describe the effects of the 2 hormones it releases
Located base of brain; made up of unmyelinated secretory neurons and is connected to hypothalamus through nerve tract
Vasopressin/ADH: helps regulate water balance and blood pressure
Oxytocin: causes uterus to contract during childbirth and immediately after delivery to prevent excessive bleeding and stimulates contractions of milk ducts in the breast which move milk to nipple
Discuss the structure of the posterior pituitary, and describe the effects of the 2 hormones it releases
Located base of brain; made up of unmyelinated secretory neurons and is connected to hypothalamus through nerve tract
Vasopressin/ADH: helps regulate water balance and blood pressure
Oxytocin: causes uterus to contract during childbirth and immediately after delivery to prevent excessive bleeding and stimulates contractions of milk ducts in the breast which move milk to nipple
Posterior pituitary release of hormones
APs travel down the axons of hypothalamic neurons, causing hormone release from their axon terminals and posterior pituitary
Posterior pituitary hormone release steps
1) hypothalamic neurons synthesize oxycotcin or ADH
2) oxytocin and ADH are transported down the axons of hypothalamic-hypophyseal tract to posterior pituitary
3) oxytocin and ADH are stored in axon terminals in posterior pituitary
4)when associated, hypothalamic neurons fire, APs arriving at the axon terminals cause oxytocin or ADH to be released into the blood
Posterior pituitary hormone release steps
1) hypothalamic neurons synthesize oxycotcin or ADH
2) oxytocin and ADH are transported down the axons of hypothalamic-hypophyseal tract to posterior pituitary
3) oxytocin and ADH are stored in axon terminals in posterior pituitary
4)when associated, hypothalamic neurons fire, APs arriving at the axon terminals cause oxytocin or ADH to be released into the blood
Anterior pituitary hormone release
Hypothalamic hormones released into special blood vessels (the hypophyseal portal system) control the release of anterior pituitary hormones
Anterior pituitary hormone release
Hypothalamic hormones released into special blood vessels (the hypophyseal portal system) control the release of anterior pituitary hormones
Anterior pituitary hormone release steps
1)when appropriately stimulated, hypothalamic neuron secrete releasing or inhibiting hormones into the primary capillary plexus
2) hypothalamic hormones travel through portal veins to the anterior pituitary where they stimulate or inhibit release of hormones made in the anterior pituitary
3)in response to releasing hormones, anterior pituitary secretes hormones into secondary capillary plexus this in turn empties into general circulation
List the 4 anterior pituitary hormones that are tropic hormones and name their glands
LH and FSH are tropic hormones that act on gonads, TSH is a tropic that acts on the thyroid, and ACTH is a tropic that acts on adrenal cortex
Topin/tropic hormones
Regulate the secretory action of other endocrine glands
-TSH
-ACTH
-FSH
-LH
Steroid hormones
-derivatives of cholesterol
-hydrophobic
-transported by carrier proteins
-typically lipid-soluble
-cross cell membrane, enter cells, and bind to intracellular receptors (cytoplasm and nucleus)- then alter transcription and translation of certain proteins
Peptide hormones
-Lipophobic- water affinity but cannot freely cross fatty membrane
-bind to cell surface receptors
-inactivated by gastric acid and peptidases
Amine Hormones
-derived from amino acid tyrosine and tryptophan
-thyroid hormones behave similarly to steroid hormones (binds to intracellular receptors)
Effect of excess thyroid hormone
Release more TSH
Paracrine
Chemical signal acts locally but affect cell types other than the releasing cells
Somatostatin
GHIH
Somatostatin
GHIH
Oxytocin
-paraventricular nucleus
-stimulated by…
-fetus stretching Cervix of uterus> activates stretch receptors in uterus>sends signal to hypothalamus>tells para. Nucleus to secrete oxytocin>binds to myometrium(middle layer of uterus)>PIP2-calcium-signaling-mechanism>increases intracellular concentration of Ca2+>enhances contraction process of muscle cells
-suckling>mechano receptors pick up signal and send to hypothalamus>releqse of oxytocin>acts on myoepithelial cells>PIP2>intracellular ca2+ levels in cell increase>enhances contractile process>ducts squeezed>milk ejected
Hyper: undesirable increase in oxytocin effects
Hypo: difficulty pushing baby out and post partum hemorrhaging
PIP2-calcium-signaling-mechanism
-hormone binds
-activates Gq protein
-binds to phospholipase C
-breaks PIP2 into DAG and IP3
-DAG:
-activates protein kinase C (phosphorylates proteins)
-ex. Phosphorylates membrane protein to allow for Ca2+ entry
-IP3:
-activates sarcoplasmic reticulum
-pushes Ca2+ out into sarcoplasm
Stimulus of ADH
Low blood pressure
-angiotensin 2 (hormone produced when blood pressure is low)
-receptor for angiotensin 2>sends signal to supraoptic nucleus to release ADH
High plasma osmolality (high solutes)
-hypertonic blood
-water volume concentration is low
-osmoreceptors pickup high plasma osmolality>tell supraoptic nucleus to release ADH
Stimulus of ADH
Low blood pressure
-angiotensin 2 (hormone produced when blood pressure is low)
-receptor for angiotensin 2>sends signal to supraoptic nucleus to release ADH
High plasma osmolality (high solutes)
-hypertonic blood
-water volume concentration is low
-osmoreceptors pickup high plasma osmolality>tell supraoptic nucleus to release ADH
How is ADH increased?
-ADH binds to vasopressin 2 receptors on cell of collecting duct
-activates Gs protein, binds to GTP and turns on Gs protein
-protein binds to adenylate cyclase which actives it
- GTP>GDP
-Gs=turned off
-ATP>CaMP
-CaMP activates protein kinase A
-protein kinase A stimulates genes of nucleus (undergoes transcription and translation>makes proteins>rough ER>golgi>packed into vesicles- has aquaporin 2 on vesicles)
-PKA phosphorylates proteins>vescicles w/ aquaporins fuses w/ cell membrane
-H2o enters from filtrations into cells of collecting duct
-h2o enters blood from aquaporin 3 and 4
H2o⬆️:
Plasma volume⬇️ >Blood pressure⬆️
Plasma osmolality ⬇️(wants isotonic: solutes=solvents)
Also:
ADH receptors on smooth muscle: vasopressin 1
-binds
-vasoconstriction
⬆️peripheral resistance>⬆️blood pressure
GH stimulated by
-⬆️AA levels in blood
-⬇️glucose levels in blood(hypoglycemia)
-⬇️fatty acids in blood
-excersize
-healthy stressors
IGF-1 protein made when…
GH binds to the liver
IGF effects on muscle
-binds to receptor on skeletal muscle cell>activates signaling pathways>activates genes> produces proteins>protein activates channels to allow amino acids to enter the skeletal muscle and converts AA into proteins which increase muscle size
Effects: ⬆️AA uptake
⬆️protein synthesis
⬆️muscle size
IGF effects on bone
⬆️osteoblast and osteoclast activity (important role in endochondral ossification)
(Protein) collagen type 1 production
⬆️proteoglycans (makes bone thicker)
IGF effects on cartilage
⬆️interstitial growth (in length):
⬆️proliferation of chondroblasts
⬆️size of chondroblasts
⬆️differentiation of chondroblasts
GH effects on liver
⬆️glyconeogenesis (making glycogen
W/o glucose)
IGF-1 production
GH effects on liver
⬆️glyconeogenesis (making glycogen in the liver from non-carb sources like AA and lactase)
IGF-1 production
GH effects on adipose
GH bonds to adipose tissue>activate hormone sensitive lipase which breaks down triglycerides into glycerol and fatty acids in a process called lipolysis
⬆️lipolysis (triglycerides breaks down into glycerol and free fatty acid)
GH effects on muscle
⬆️AA uptake
Prolactin
Peptide
Stimulate alveolar cell to produce milk
-mammary gland- modified apocrine gland
-lobules- consist of alveolar cells which produce milk
Arcuate nucleus produces PIH= dopamine
PIH acts on lactotrope to inhibit cell from releasing prolactin
Paraventricular nucleus secretes TRH>binds to receptors on lactotrope>gives stimulating signals>produces prolactin
Estrogen stimulates prolactin and can inhibit arcuate nucleus from producing PIH (after birth of baby, estrogen levels slowly fall, because extremely high estrogen levels do not allow prolactin to act on alveolar cell)
Breast feeding>stimulates production of oxytocin and prolactin
Nucleus
Group of cell bodies in CNS collectively joined together in a specific area which is unmyelinated and forming gray matter
Tract
Bundle of axons grouped together in CNS
Hypothalamus gray matter nuclei
1) Supraoptic nucleus
2) paraventricular nucleus
3) arcuate nucleus
4) preoptic nucleus
Infundibulum
Connection between hypothalamus and hypophysis (pituitary gland)
Anterior pituitary
“Adenohypophysis”
-glandular cuboidal epithelium
-originates from pharyngeal mucosa
Posterior pituitary
“Neurohypophysis”
-neural tissue- pituicytes (glial cells)
Hypophyseal tract
-neural connection
-between hypothalamus and neurohypophysis (posterior pituitary)
Hypothalamic hypophyseal portal system
-portal system- connection between 2 capillary beds by a portal vein
-between the hypothalamus adenohypophysis (anterior pituitary)
Supraoptic nucleus
-secretes ADH
-After it created it is transported down the axons
-in synaptic vescicles
-by specific motor proteins
-vescicles need stimuli to release ADH
➕ of ADH secretion
1) ⬇️BV➡️⬇️BP
2) ⬇️osmolality (plasma)
3) pain
➖ of ADH secretion
1) ⬆️BV
2) ⬆️ osmolality (plasma)
3) alcohol
Paraventricular nucleus (posterior)
-2
- secretes oxytocin
-after created, it is transported down the axons, the synaptic vescicles by specific motor proteins
-vescicles need certain stimulus to release oxytocin
➕ of oxytocin
1) birthing process
2) suckling by baby on mother’s mammary glands
-receptors on areola
3) male ejactulation
Arcuate nucleus secretes
1) GHRH
2) PIH/ dopamine
Arcuate nucleus: secretion of GHRH
-after it’s created through hypophyseal portal system to the secondary capillary plexus of the adenohyphysis
-➕somatotropes
-produce GH
Arcuate nucleus: PIH/dopamine secretion
-after it’s created it goes through hypophyseal portal system to the secondary capillary plexus if adenohyphysis
-➖ lactotrope
- prevents them from secreting prolactin
-⬇️PIH➡️ lactropes produces prolactin
Paraventricular nucleus
-2
-secretes:
1) CRH- anterior
2)thyrotropin- releasing hormone (TRH)- anterior
3) oxytocin- posterior
Paraventricular nucleus: secretion of CRH
-after it’s created, it goes through hypophyseal portal system to the secondary capillary plexus of adenohypophysis
-➕ corticotropes
-produce proopimelanocortin (POMC)
-POMC is broken down into:
1) alpha-melanocyte ➕hormone (alpha-MSH)
2)adrenocorticotropic hormone (ACTH)
Paraventricular hormone: secretion of TRH
-after it’s created, it goes through hypophyseal portal system ➡️ secondary capillary plexus of adenohypophysis
-➕ thirotropes
-produce thyroid-➕ hormone (TSH)/ thyrotropin
Preoptic nucleus
-anterior pituitary
-secretes gonadotropin releasing hormone (GnRH)
-After it’s created it goes through the hypophyseal portal
system to the secondary capillary plexus of the adenohypophysis
-It stimulates specific cells – gonadotropes
o They produce specific proteins - Follicle stimulating hormone (FSH) and Luteinizing hormone (LH).
FSH vs LH release
FSH and LH are released in different amounts, at different times
o ↑ concentrations GnRH, frequently → LH is secreted
o ↑ concentrations GnRH, rarely → FSH is secreted
⬆️GnRH➡️⬆️LH
⬇️GnRG➡️⬆️FSH
CRH cause release of
ACTH
TRH causes release of
TSH
CRH secondary triggers
-fever
-hypoglycemia
-long term stress
TRH secondary triggers
-cold temp
-pregnancy
GRGH secondary triggers
-hypoglycemia
-⬆️AAs in blood
-⬇️fatty acids in blood
-exercise
Aquaporin 2 is phosphorylates by
Protein kinase A via G stim process when ADH activates receptor
Peptide hormone
-H2O soluble
-don’t pass freely through lipid-bilateral (require receptor on cell membrane (2nd messenger))
-oxytocin
-insulin
-glucagon
-FSH
-LH
-GH
-PTH
Steroid hormones
-lipid-soluble (derived from cholesterol)
-pass through lipid bilayer
- bind to receptors inside cell membrane
-testosterone
-estrogen
-progesterone
-Gonadocorticoids
-cortisol
ADH: effect on vessels
-receptors on smooth muscle cells (blood vessels)
-ADH binds to receptors and ➕Gq protein mechanism ➡️ Ca2+ levels in cells
-vasoconstriction
-⬆️peripheral resistance
-⬆️BP
Syndrome of Inappropriate ADH Secretion (SIADH)
Hypersecretion of ADH
-causes
1)tumor (hypothalamus/P. Pituitary)
2) bacterial infection- destroys different tissues causing ⬆️ADH
3) meningitis
-effects- H2O located in CD goes into principal cell and into blood
Diabetes insipidus
Hyposecretion of ADH
-cause: severe trauma to head
-damages to hypothalamus/p. Pituitary
-prevents ADH secretion
-⬇️ADH
-polyuria- ⬆️⬆️⬆️H2O loss through urine
-polydipsia- persisting feeling of thirst
GH secondary stimuli
1)⬆️AA
2) ⬇️glucose in the blood
3) ⬇️fatty acids
4)excersise
5) healthy stressors
GH ➕
Arcuate nucleus ➡️ GHRH➡️ hypophyseal portal system ➡️ somatotrope➡️ GH release
GH affect on liver
1) Produces Insulin- like growth factor type 1
2) Gluconeogenesis- produces glucose from non-carbohydrate carbon substrates (lipids, proteins, or breakdown products of these substances)
GH effect on adipose
Lipolysis (breakdown of triglycerides into glycerol and fatty acids)
GH effects on skeletal muscle
⬆️AA uptake
GH acts on what structures?
1) liver
2) adipose
3) skeletal muscle
Insulin-like growth factor effect on skeletal muscles
1)amino acid uptake
2)↑ the overall size of the muscles (protein synthesis)
Insulin-like growth factor effect on bone
1)↑ bone deposition (osteoblasts)
2)↑ bone resorption (osteoclasts)
3) appositional growth (⬆️ diameter)
4)↑ endochondral ossification (replace cartilage w/ bone)
Insulin like growth factor effect on cartilage
⬆️interstitial growth (length of the bone)
1)↑ differentiation (of chondroblasts) into certain types of bone tissue
2)↑ size of chondroblasts
3)↑ proliferation (rapid⬆️ in #s) of chondroblasts
Insulin like growth factor acts on what structures?
1)skeletal muscle
2)bone
3)cartilage
Prolactin synthesized by
Lactotropes in A. Pituitary
Prolactin ➕
1) TRH
-secreted by paraventricular nucleus
-goes through hypophyseal portal system to secondary capilllary plexus in A. Pituritary
-➕ lactotropes
➕prolactin secretion
2) breast feeding
-direct➕
-suckling ➕mechano receptors
-triggers production of oxytocin and ➕production of prolactin
-suckling ➕paraventricular nucleus. To release more TRH➡️➕lactotropes
3)⬆️estrogen
-during pregnancy, birthing process, and after birth process
-➕prolactin directly- in lactotropes
-➕prolactin indirectly-➖ arcuate nucleus (in secreting PIH)
Follicular cells
Make up thyroid follicles
-simple cuboidal epithelium
TH sysnthesis begins in
Paraventricular nucleus
-secretes TRH (➕thyrotropes➡️TSH)
In luminal space: 3 functions of peroxidase (enzyme)
1) iodine oxidation
-converts I-➡️I2
-loses e-
2) iodination
-attaches 1 or 2 I2 to the tyrosine AA’s in thyroglobulin colloid
-1 molecule creates MIT
-2 molecules crease DIT
3) coupling
-couples the iodinated AAs into T4 and T3
-DIT +DIT= T4
-DIT + MIT= T3
Pendrin
Transports I- from follicular cells➡️ luminal space
Thyroxine Binding Globulin (TBG) synthesized by
The liver
Steps of thyroid sysnthesis
1) TRH release from hypothalamus
2) anterior pituitary releases TSH
3) TSH➕follicular cells to synthesize TGB (thyroid globulin)
4) Iodide trapping
5) oxidation of I- (TPO)
6) ionization of tyrosine AA
7) couples DIT and MIT
8) endocytosis of TGB w/ T3 and T4
9) lysosomal enzymes cleave T3 and T4
10) exocytosis of T3 and T4 into blood plasma (bound to TBG)
TH effect on the cells: ⬆️Na+/K+ pump usage➡️ burning ATP➡️ADP results in:
-⬆️O2 usage
-⬆️metabolic rate
-⬆️heat production
-⬆️# of mitochondria
-hypertrophy (get bigger) of mitochondria
TH transported in what form:
T4
TH active form:
T3
TH effects on liver
1) glycogenolysis (glycogen➡️glucose)
2) gluconeogenesis (lactate, AA, glycerol➡️glucose)
-both result in ⬆️glucose in the blood
3) ⬆️LDL (low density lipoprotein- bad cholesterol) uptake into the liver
TH effects on the ❤️
-➕ expression of receptors for epi and NE
-when bound:
-⬆️contractility
-⬆️SV
-⬆️CO
-⬆️BP
-➕expression of receptors on non contractile cells (when epi and NE bind):
-⬆️HR
-⬆️BP
TH effect on CNS
1)⬆️Dendrite production
2)⬆️myelination➡️⬆️speed of APs
-hyperthyroidism: anxiety, irritability
3)⬆️synapses
TH effects on Bones
1) ➕interstitial ossification (⬆️length)
2) ➕endochondral ossification (replace hylaine cartilage with bone
3) bone remodeling (regulating osteoblasts and osteoclasts activity: balance)
Effects of TH on adipose
-➕lipolysis (breakdown of triglycerides into glycerol and fatty acids)
-glycerol goes to liver to be converted to glucose (gluconeogenesis)
-hyperthyroidism: thin
Effects of TH on muscles
Regulate catabolism (proteins➡️AAs) and anabolism (AAs➡️proteins)
-hyperthyroidism: ⬆️catabolism➡️ weak muscles- atrophy
TH effects on skins and hair
⬆️metabolic rate
-⬆️body temp
-vasodilation
-skin looks flushed and radiates heat
-apocrine and merocrine glands produce sweat
Hyperthyroidism: thick hair
Hypothyroidism: thin, brittle hair
TH effect on GI tract
- ➕gland secretion of GI tract
- ⬆️motility
Hyperthyroidism: diarrhea
Hyperthyroidism: constipation
Chief cells
Responsible for secreting PTH
➕of PTH
Ca2+: humoral ➕
Parafollicular cells
“C cells”
-➕ by ⬇️Ca2+ (humoral)
-release calcitonin
Calcitonin
➕by ⬆️Ca2+
-➖osteoclasts to prevent Ca2+ and phosphate release into the blood
-bone gets thicker
Liver location
Right side
Spleen location
Left side
Layers of adrenal cortex
1) zona glomerulosa
-most superficial
2) zona fasiculata
-middle
-thickest
3) zona reticularis
-deepest
Adrenal medulla made up of
Neural tissue
Zona glomerulosa produces what hormone?
Aldosterone
Aldosterone ➕
1)angiotensin 2
2)⬇️Na+/⬆️K+
3) ACTH (weaker)
ACTH➕
Paraventricular nucleus secretes CRH
-goes into hypophyseal portal system
-➕corticotropes to release ACTH
Aldosterone acts on…
DCT
➖of aldosterone
ANP
Steroid hormones
Derived from cholesterol
-testosterone
-progesterone
-aldosterone
-estrogen
-cortisol
