Group 6 - Endocrine System Flashcards
network of different organs, mainly glands that secrete various chemicals called hormones that regulate or manage different bodily functions
endocrine system
what does the endocrine system secrete
hormones
where does the endocrine system mainly revolve around
- control
- development
- management
endocrine system is the core organ system of what?
- homeostasis
- cell communication and signaling
Three parts of the endocrine system
- endocrine cells
- hormones
- receptors
recognizes hormonse
receptor
any factors that trigger response
stimuli
specialized protein that protrudes through the surface of a cell membrane, receiving different molecules called stimuli
receptors
molecules which receptors receive
stimuli / ligand
- specialized cells that are the producer or secretor of hormones
- produce different hormoes that are specified to certain cells depending on what type of hormone
- can be found in different parts of the body
endocrine cells
- specialized hybrid of endocrine cell and neurons
- can respons to electric signals like a neuron, but releases hormones as a response like an endocrine cell
- also produces neurotransmitters that is used as a hormone
neuroendocrine cell
eg. of neurotransmitters neuroendocrine cells release
- epinephrine
- oxytocin
tend to act like endocrine system but they are mostly on supporting other existing body parts
exocrine
why do endocrine glands secrete hormones
response to change or imbalance in the body
- signaling molecules are released via circulation to reach to other body sites
- molecules are then received by receptors
endocrine signaling
free hormone + binding protein
hormone-protein complex
how hormones goes around the body
- paracrine signaling
- autocrine signaling
releases hormones around the perimeter in nearby cells
paracrine signaling
releases hormones aroung the perimeter to stimulate the same cell
autocrine signaling
Two main ways as to what happens to the hormones afterward
- metabolize
- excretion
- hormones that are attached to the cells will be taken inside the cell
- they will be degraded or broken apart to be used for other cellular processes
metabolize
how are hormones taken inside the cell
via receptor-mediated endocytosis
- hormones will eventually separate to the receptor and be broken down by enzymes such as the liver
- eventually be filtered out by the kidney as metabolic waste
excretion
how do hormones separate from the receptor
via desensitization or degradation
specialized organs that produce and secrete hormones directly into the bloodstream
specialized organs
involves outside of the brain
peripheral
involves glands found in the brain
central
Different endocrine glands
- hypothalamus
- pituitary gland
- thyroid gland
- parathyroid gland
- adrenal glands
- pancreas
- testes
- ovaries
located in the brain, control the pituitary gland and regulats many bodily functions
hypothalamus
often called the “master gland”, it secretes hormones that control the activity of other endocrine glands
pituitary gland
term used to the pituitary gland
master gland
located in the neck, it produces hormones that regulate metabolism
thyroid gland
four small glands located near the thyroid, they control calcium levels in the blood
parathyroid glands
situated on top of the kidneys, they produce hormones that manage stress, blood pressure, and metabolism
adrenal glands
located in the abdomen, it produces insulin and glucagon, hormones that regulate blood sugar levels
pancreas
produce testosterone, a hormone that influences male sexual development and characteristics
testes
produce estrogen and progesterone, hormones that control the menstrual cycle and pregnancy
ovaries
Three main classes of hormones
- amines
- peptides and proteins
- steroids
where are hormone receptors found
- cell surface (water-soluble)
- cytoplasm or nucleus (lipid-soluble)
Two types of action
- water-soluble action
- lipid-soluble action
- cannot directly cross the cell membrane
- bind to receptor proteins embedded in the cell
- binding initiates a series of events known as a signal transduction pathway
water-soluble action
water-soluble hormones
- peptides
- proteins and amines
what is initiated in the binding of water-soluble action
signal transduction pathway (uses 2° messenger like cAMP)
- can directly cross the cell membrane
- bind to intracellular receptors located in the cytoplasm or nucleus of the target cell
lipid-soluble actions
lipid-soluble hormones
- steroids
- thryoid hormones
what do lipid-soluble hormones influence
gene expression
Function of hormone receptors
- initiation of cellular responses
- regulation of gene expression
- maintenance of homeostasis
Different stimuli for hormonal secretion
- neural
- hormonal
- humoral
hormone secretion may be stimulated by neural input to the endocrine cells
neural
another hormone also act on the endocrine cell
hormonal
- changes in the plasma concentrations of mineral ions
- organic nutrient directly controls the secretion of several horomones
humoral
secretion of hormone is stimulated or inhibited by a change in the level of a specific extracellular parameter
physiological response-driven feedback loop
involves a three-tiered configuration
endocrine axis-driven feedback loop
Three-tiered configuration of the endocrine axis-driven feedback loop
- hypothalamic neuroendocrine neurons
- pituitary glands
- peripheral endocrine gland
control blood glucose level
pancreatic islet cells
control of blood calcium ion and inorganic phosphate levels
parathyroid gland and kidneys
control blood osmolarity
- hypothalamus
- posterior pituitary gland
Endocrine axis-driven feedback loop
- hypothalamic neuroendocrine neurons
- releasing hormone
- pituitary gland
- tropic hormone
- peripheral endocrine gland
- hormone
- target organs
- physiological effects
first tier
hypothalamic neuroendocrine neurons secrete releasing hormones
second tier
releasing hormones stimulate/inhibit the production/secretion of tropic hormones from pituitary gland
hormones that stimulate the secretion of other hormones by endocrine glands
Tropic hormones
third tier
tropic hormones stimulate production and secretion of hormones from the pituitary endocrine glands
contrls the amount of hormone in the system
hormone axis
what does the hypothalamus secrete
- antidiuretic hormone (ADH)
- oxytocin
into the circulation at neurohypophysis
Hormones of Hypothalamus
- Thyrotropsin-releasing Hormone (TRH)
- Corticotropic releasing Hormone (CRH)
- Gonadotropin releasing Hormone (GNRH)
- Growth Hormone releasing hormone
- Somatostatine (growth hormone inhibiting Hormone (GHIH)
- Dopamine (prolactin- inhibiting Hormone) (PIH)
- works as a unit with the hypothalamus
- stores and release oxytocin and antidiuretic hormone produced in the hypothalamus
posterior pituitary gland
- secretes hormones that control a wide range of bodily activities
- regulated by hypothalamus’ releasing hormones and inhibiting hormones
anterior pituitary gland
what does the hypothalamus secrete that regulates the anterior pituitary gland
- releasing hormones
- inhibiting hormones
hormones of the pituitary gland
- neurohypophysis
- adenohypophysis
- regulates metabolism
- promotes tissue growth especially of bones and muscles
growth hormone (GH)
stimulates growth and activity of thyroid gland and secretion of T3 and T4
thyroid stimulating hormones (TSH)
stimulates the adrenal cortex to secrete glucocorticoids
adrenocorticotropic hormone (ACTH)
stimulates growth of breast tissue and milk production
prolactin (PRL)
- stimulates production of sperm in the testes
- stimulates secretion of oestrogen by the overies
- maturation of ovarian follicles
- ovulation
follicle stimulating hormone (FSH)
- stimulates secretion of testosterone by the testes
- stimulates secretion of progesterone by the corpus luteum
luteinising hormone (LH)
- sits on thyroid cartilage of larynx
- consists of 2main lobes connected by the isthmus
- controls metabolism
- involved in calcium homeostasis
thyroid gland
bridge of tissue that connects the two lobes of the thyroid gland
isthmus
produced by thyroid gland to control metabolism
- thyroxine (T4)
- triiodothyronine (T3)
essential for the formation of thyroid hormones
iodine
process where thyroid gland selectively takes up iodine from the blood
iodine trapping
stimulates the release of T3 and T4 into the blood
thyroid stimulating hormone (TSH) from anterior pituitary
causes simple goiter
iodine deficiency
function of T3 and T4
normal growth and development, esp. of skeleton and nervous system
produced in response to stress
- cortisol
- adrenaline
how is the cortisol produced
- hypothalamus -> corticotropic-releasing hormone (CRH)
- pituitary glands -> adrenocorticotropic hormone (ACTH)
- cortisol production
cortisol to liver
produce glucose
cortisol to immune cells
- change responses or
- temporarily inhibit immune response
effects of over-exposure of cortisol
- weight gain
- depression or anxiety
- headaches
- sleep problems
hormone stress response mainly for fight or flight
adrenaline
adrenaline are more responsible to what
faster reactions
hormone for regulation of blood sugar levels
insulin
how is glucose regulated
- pancreatic beta cells receives glucose
- ATP synthesis
why is insulin released
- overproduction of ATP
- induce multiple potassium channels that depolarize cell
- activates calcium channels as response
- massive release of insulin
important proteins to remember in insulin pathway
- IRS - insulin-receptor substrate
- PI3K - phosphoinositide-3 kinase
- PIP3 - phosphatidylinositol (3,4,5)-triphosphate
- Akt - protein kinase B (PKB)
Two categories of endocrine disorder
- secretion
- responsiveness
secretion disorder
- hyposecretion
- hypersecretion
responsiveness disorder
- hyporesponsiveness
- hyperresponsiveness
Different endocrine disorders
- Cushing’s syndrome
- Addison’s disease
- Grave’s disease
- Insulin resistance
- cortisol hypersecretion
- result to long-term effect of exposure to cortisol throughout the body
- can be caused by medicine, or tumors in the adrenal glands
- high blood pressure, increased mass and bruising
Cushing’s syndrome
- hyposecretion of adrenal hormones that may be due to damaged glands or by genetics
- low hormone counts usually include cortisol and aldosterone
- have less but noticable effect on body ranging from loss of weight, problems with GI or skin color changes
Addison’s disease
- thyroid hyperresponsibeness
- autoimmune disorder that causes the thyroid to be overstimulated
- done by overproduction of thyroid-stimulating immunoglobins (TSI)
- receptors of thyroid is exposed with antibodies and keeps producing thyroid hormones
- cause hyperthyroidism and more
Grave’s disease
- insulin hyporesponsiveness
- long-term disorder that involves overexposure to insulin
- occurs over time where too much insulin leads to less sensitivity of receptors
- glucose stays and more insulin in produced
- core cause of Type II diabetes
insulin resistance