Unit 13: Endocrine System Flashcards
Endocrine System
Glands that secrete different chemicals in the blood
Travel throughout the body to their _____ ____ to initiate their _______
target site
effect
Endocrine system function (6) Maintenance of…
Maintenance of the internal environment
Temperature Fluid Volume Osmolarity Adaptation to stress growth + metabolism reproduction
_______ + _______ lasting effects
slower + longer
more widespread
______ affects many _____ of the body at a ______ by secreting _______ into the _______.
indirectly organs distance chemicals blood
Glands
group of specialized cells that synthesize + store and release chemicals into the blood
Hormones released into the bloodstream circulate throughout the body to specific _____ _____ that have ______ for the hormone
target cells
receptors
Hormone will then have its effect on the target cells and either ______ or ______ the ______ of the cell
stimulate
inhibit
activity
Adrenal Gland
Above the kidneys
Secretes Aldosterone, Cortisol and Androgen
Pancreas
Above the kidneys
Secretes
Insulin
Glucagon
Stomatostasin
Thyroid
In the throat
secretes
T3 + T4 + Calcitonin + Parathyroid hormone
Hypothalamus + Pituitary Glands
Located in the brain.
Hypothalamus secretes releasing hormones; pituitary secretes stimulating hormones
Hormones derived from tyrosine
Thyroxine
Triiodothyronine
Hormones derived from proteins
Calcitonin
Parathyroid Hormone
Pituitary + pancreatic hormones
Releasing hormones from the hypothalamus
Steroid Hormones (5)
Aldosterone Cortisol Estrogen Progesterone Testosterone
______ ______ of hormone determines the way it is carried in the blood + act on the target cell
chemical makeup
Hydrophilic Proteins
Cell surface receptors
Circulate freely through the blood
Cannot diffuse through the cell membrane
Steroid/Thyroid hydrophobic hormones
Can’t diffuse through the blood is transported on carriers.
Can diffuse through the cell membrane
Acts on receptors in the cytoplasm or on the nucelar membrane
Secreted into the blood in ______ by very specific ______
pulses
stimulus
neural + blood born
Amoun released can vary according to the _______ of the stimulus
strength
once secreted by the gland hormones are present in very ______ ______ in the blood
small concentrations
Receptors
a unique strcuture in or on a cell that interacts with a chemical in a particular way
Type of hormone determines where the receptor is located
Hydrophobic: Cytoplasm + Nucleus membrane
Hydrophilic: Cell membrane
Hydrophobic hormone binding
Receptors can be localized in the cytoplams or on the nuclear membrane.
the hormone must first be released by the protein carrier before it enters the cell.
the hormone binds with its receptor in the cyto/nucleus
the hormone/receptor complex will then bind to DNA w/in the nucleus and alter various activities of the cell
these activities could be increased/decreased by the production of proteins
Receptors for hydrophilic hormones
Unable to diffuse through the cell membrane
hormone binds to the receptors on the cell membrane.
When a hormone binds the receptors it initiates a sequence of chemical reactions that will eventually alter the activity of the cell
Three ways a membrane receptor can alter the cell function
Tyrosine kinase:
hormone+receptor complex activates tyrosine kinase on the inside surface of the membrane
tyrosine kinase alters existing proteins that will alter the activity of the cell
Gprotein:
when a hormone a G-protein is activated that lies w/in the cell membrane
G protein can then open ion channels
Secondary Messenger System:
Hormone binds receptor G-protein on the inside of the membrane produces a second receptor
Cyclic adenosine monophosphate
Secondary messenger is released into the cytoplams and will rapidly alter the proteins already present in the cell
altered proteins will trigger a sequence of reaction inside the cell
Hormones that have their effects on their target tissue are broken down into different systems in the body
Tissues can break hormones down (liver and kidneys)
Can be excreted into the bile or excreted through the kidneys
Hypothalamus
Below the thalamus and above the pituitary
Base of the brain
made up of nerve cells bodies
nuclei control the release of hormones from the pituitary glands/body
Hypothalamus 2 Regulates two systems
Homeostatic:
Temperature
Water balance
Energy production
Behavioural:
Hunger
Thirst
Sex
Releasing/Inhibiting Hormones
Triggers release of hormones from the anterior pituitary
Prolactin releasing/inhibiting hormones
Gonadotropin
Growth Hormone Releasing/Inhibiting Hormone
Thyrotropin releasing hormone
Pituitary glands
Divided into anterior and posterior pituitary
Anterior Pituitary
Made from tissue that comes from the roof of the mouth.
endocrine cells in this area secrete pituitary hormones directly into the blood
Releases:
Prolactin releasing hormone Thyroid releasing hormone FSH LH GH
Hormone release is stimulated through the release of releasing/inhibiting hormones into the hypothalamic-hypophyseal portal system
Posterior pituitary
Made from the neural tissue found in the hypothalamus
Releases:
Antidiuretic Hormone (Vasopressin)
Oxytocin
Neurons produce neuro hormones; located in the hypothalamus secreted in the blood from the posterior pituitary in response to APs
Hypothalamus stimulates the release of hormone through the hypothalamic-hypophyseal tract
The cell bodies lie in the hypothalamus.
Axons + nerve terminals lie in the pituitary
Hormones of the AP control many _____ functions throughout the body
Metabolic
Anterior Pituitary hormone control
Growth of ovaries + testes
control their reproductive functions
Thyroid releasing hormone causes the release of thyroid-stimulating hormones
Corticotropin-releasing hormone stimulates the release of adrenocorticotropic hormone from AP
Growth hormone is under the control of two hypothalamus hormones
GnRH stimulates AP to secrete both FSH and LH
Prolactin releasing hormone + prolactin inhibting hormone control the release of prolactin from the pituitary
Posterior Gland
Secreted form PP manufactured by nerve cells whose cell bodies lie in the hypothalamus.
Hormones are carried down to the terminal ends of the nerve + released in response to AP
Negative Feedback: Short Loop
Releasing hormone secreted by hypothalamus (H1)
Cause the release of an AP hormone (H2) into the blood
H2 can feedback to the hypothalamus + decrease the release of H1
Negative Feedback: Long Loop
AP hormone will ciruclate to an endocrine gland to cause the release of another hormone H3
H3 can feedback to the hypothalamus/pituitary to decrease the release of H1 and H2
Negative Feedback: Ultra Long Loop
H3 can affect one or more target tissues
Tissues response can feedback to the hypothalamus and decrease the release of it shormone H1
TSH
thyroid stimulating hormone is secreted from the anterior pituitary and acts on the thyroid gland to stimulate the release of T3 and T4.
T3 and T4 then inhibit the release of TSH from the pituitary/hypothalamus
ACTH
Aderoncorticotropic hormone
stimulates the release of aldosterone, cortisol and androgen from the adrenal glands.
cortisol feeds back to the hypothalamus/pituitary inhibiting the release of ACTH+corticotropin
GHRH/GHIH
Stimulates the release of GH from the anterior pituitary.
GH feeds back to the hypothalamus to reduce the release of GHRH
FSH/LH
Stimulates the release of estrogen/testosterone from the gonads
sex steroids loop back to the pituitary and hypothalamus to decrease the release of FSH + LH+ GnRH
Thyroid Gland Location + structure
Below the Larynx
Two lobes surrounding the trachae
Made up of follicles
Central region of the colloid
Surrounded by epithelial cells
Parafollicular cells lie between the follicles
Function of the Thyroid
Secretes Triiodothyronine and Thyroxine
Hormones are responsible for regulating the basal metabolic rate of the body
T3/T4 are from the hydrophobic
Tyrosine
Requires iodine
T3/T4
2 TYR and 3 iondine
2 TYR and 4 Iodine
_____ cells produce the protein hormone
Follicle
Calcitonin
Decreases calcium levels in the blood
_ _ _ stimulates final growth
TSH
Regulation of Secretion of T3/T4
T3/T4 feedback to the hypothalamus + pituitary to inhibit the release of thyrotropin-releasing hormone + thyroid stimulating hormone
Circulation of T3/T4
90% of hormones released from the thyroid gland consist of thyroxine.
10% consist of triiodothyronine
Both are hydrophobic and circulate in the blood on protein carriers
T4 is more abundant but converted into T3
T3/T4 are produced inside the
follicles of the thyroid gland
______+_____ with the help of a _____ ______
Iodine + tyrosine
glycoprotein
thyroglobulin
Epithelial cells
take up the molecules of tyrosine from circulation
they combine with thyrogloculin produces in the cells
take up iodine absorbed from diet
Tyrosine + thyroglobulin complex
Secreted into the colloid one or two molecules of iodine attach to each tyrosine
two tyrosine molecules will join while attached to the thyroglobulin
of iodine molecules attached to the tyrosine will either produce T3 or T4
Secretion of T3/T4
TSH released from the pituitary will bind the receptor on the membrane of the epithelial cell which will stimulate a # of reactions
Taking up of circulating iodine
stimulated endocytosis of T3/T4-thyroglobulin complex into the cell
removal of thyroglobulin from T3 + T4 in the epithelial cell
secretion of T3 + T4 in the blood
Production of t3/t4
Produced inside the follicles of the thyroid glans
iodine and tyrosine w/ the help of glycoprotein thyroglobulin
epithelial cells take up molecules of tyrosine from circulation + combine with thyroglobulin produced in the cells
tyrosine thryglobulin complex is secreted into the colloid one or two molecyles attach to each tyrosine
two tyrosine molecules will join together while attached to thyroglobulin
Effects of T3/T4 on the Body
Diffuse through the cell membrane
Receptors found on the nucleus
majority of the enzymes that affect metabolic activity of the cells
T3/T4 are responsible for the development of the ______ _____ in the fetus
nervous system
T3/T4 maintain/increase
Alertness
responsiveness
emotional state
Body temperature CO Ventilation Food intake break down of energy stores
Hyperthyroidism
High BMR
Sensitive to warm room room temperature
weight loss due to increased fat breakdown/decreased fat storage
rapid heart rate
hyperactive + nervous activity
Goiter
enlargement of the thyroid gland
insufficient iondine in the diet or to much thyrotropin releasing hormone and TSH
A _____ tumor can cause an excess secertion of TSH/TRH
hypothalamic
TSH in excess makes the thyroid grow uncontrollably
W/out Iodine in the blood
the thyroid will be unable to produce T3/T4
No negative feedback to the hypothalamus/pituitary and they will continue to prpduce TSH/TRH
Calcitonin is a
Protein hormone secreted by the parafollicular cells of the thyroid
Parafollicular cells make up
0.1% of the thyroid gland in humans
Calcitonin is secreted when
Ca++ blood levels are high
decreases the number + activity of special bone dissolving cells (osteoclats)
stimulates the secretion of calcium in the urine
works with the parathyroid hormone to maintain ca++ levels in the blood
Parathyroid glands + PTH
Posterior side of the thyroid
4 glands in humans
secretes PTH
PTH works antagonistically to calcitonin
PTH effects
increases number and activity of osteoclats
decreases the excretion of ca++ in urine by reabsorbing it into the filtrate
Hypothyroidism (cretinism)
Before/after birth or during childhood
dwarfism + developmental delays
thyroid hormone treatment
Hypothyroidism congenital lack of a thyroid gland
inability to synthesize T3/T4
Lack of Iodine
- sensitive to cold temperature
- weight gain
- low blood pressure
- slow reflexes + apathy + lethargy
- depression
- easily fatigued
