Hormones Flashcards
What are classical endocrine hormones?
Hormones that act on distant tissues to regulate metabolic function
Tend to be long lasting
What are the 2 local hormone types?
Paracrines and autocrines
What do paracrines do?
Act on target cells near release site
What do autocrines do?
Act on the cells that secreted them
What is the difference between classic and local hormones?
Classic - long lasting
Local - short lived
Classify hormones based on their chemical nature
Steroids (cholesterol)
Peptides and Glycoproteins
Amines
Eicosanoids
Describe steroid hormones
Derived from cholesterol
Circulate bound to carrier proteins to allow higher levels in blood
Mostly gonadal and adrenocortical
Give examples of steroid hormones
Pregnanes (Cortisol, Progesterone)
Androstanes (Testosterone)
Estranes (Estradiol)
What types of hormones are derived from cholesterol?
Steroids
What type of hormone are estradiol, tesosterone, and cortisol?
Steroids
Describe peptide hormones
Made from larger pro-hormones
Released into blood or stored in granules in producing cell
Bound to carrier protein in plasma to prevent proteolysis
Give examples of peptide hormones
Insulin
Glucagon
Parathyroid hormone (PTH)
Human Growth hormone (HGH)
What type of hormone are insulin, glucagon, PTH, and HGH?
Peptides
Describe glycoprotein hormones
2 alpha and 2 beta chains (alpha chains identical in all)
Water soluble, no carrier protein required
Short half life
Give examples of glycoprotein hormones
Follicle stimulating hormone (FSH)
Luteinizing hormone (LH)
Thyroid stimulating hormone (TSH)
Human chorionic gonadotropin (hCG)
What type of hormone are FSH, LH, TSH, and hCG?
Glycoproteins
Describe the polypeptide units in glycoprotein hormones
2 alpha and 2 beta
2 alpha the same in all hormones
2 beta chains differ between hormones, dictate functional properties and antigenicity
Give an example of how immunoassays might work against glycoprotein hormones
hCG immunoassays target the specific beta subunit in the hormone
Describe amine hormones
Derived from decarboxylated amino acids
Some circulate bound to carrier proteins to prevent filtration by kidneys due to their small size
Give examples of amine hormones
Epinerphrine, norepinephrine (circulate free, short lived)
Thyroxine (T4), Triiodothyronine (T3
circulate bound, long lasting)
What type of hormone are T3, T4, epinephrine, and norepinephrine?
Amines
Describe eicosanoids
Derived from arachidonic acid (fatty acid)
Give examples of eicosanoid hormones
Prostaglandins
Leukotrienes
What kind of hormone are prostaglandins and leukotrienes?
Eicosanoids
Why are sensitive methods needed to measure hormones?
They have very low levels in the blood
How do hormones affect cells with receptors outside the cell?
First messengers bind and activate receptors causing an increase or decrease in the synthesis of the second messenger in the cell which activates the desired metabolic process
What hormones act as first messengers?
Lipid insoluble amine hormones (most) and peptide hormones
How do hormones affect cells with receptors inside the cell?
Hormones release from their carrier proteins and diffuse into the cell and bind with receptors
The complex then binds to a hormone responsive element in the DNA
What hormones can diffuse into cells to activate receptors?
Fat soluble hydrophobic steroids and thyroid hormones
What 3 ways can hormone release be controlled?
Humoral
Nervous
Hormonal
Describe humoral hormone control
Release controlled by concentration of a substance in the blood
Give an example of humoral hormone control
Blood glucose levels influence secretion of glucagon and insulin
Blood calcium levels affect parathyroid for PTH release
Describe nervous hormone control
Nerves stimulate release
Give an example of nervous hormone control
Neurons stimulate release of epinephrine from adrenal glands
Describe hormonal hormone control
Release controlled by other hormones
Give an example of hormonal hormone control
Hormones from the hypothalamus stimulate the pituitary to release other hormones
What 3 factors affect the amount of hormone that reaches the target cells?
Rate of production
Rate of delivery (blood flow)
Rate of degradation/elimination
Describe the difference between shutting off a hormone with a short vs long half life
Short half life = blood level decreases rapidly
Long half life = blood level may persists for some time
Glucose influencing the release of glucagon and insulin is what type of hormone control?
Humoral
Neurons stimulating the release of oxytocin from the pituitary is what type of hormone control?
Nervous
Hypothalamus hormones stimulating hormone release from the pituitary is what type of hormone control?
Hormonal
How does a negative feedback loop work?
The products of the pathway inhibit the reaction that formed them
How are hormone levels usually controlled?
Negative feedback loops
Give an example of a negative feedback loop
T3/T4 regulation
When T3/T4 drops below the threshold neurons in the hypothalamus secrete TRH
TRH stimulates the pituitary to secrete TSH
TSH binds to the thyroid to stimulate production of T3/T4
T3/T4 levels rising inhibits release of TRH
What does the hypothalamus do?
Secretes hormones to stimulate or suppress the release of hormones from the pitutary
What does the pineal body do?
Produces melatonin
What does the pituitary gland do?
Releases hormones to control many functions of other endocrine glands
What does the thyroid do?
Hormones play a role in body metabolism and calcium balance
What do the parathyroid glands do?
Regulate calcium balance via PTH
What does the thymus do?
Produces t-lymphocytes
What do the adrenal glands do?
Work with the hypothalmus and pituitary gland
Antidiuretic hormone (ADH) Source, target, function
Hypothalamus, stored and released by posterior pituitary
Kidney
Water resorption
Oxytocin
Source, target, function
Hypothalamus, stored and released by posterior pituitary
Uterus and breasts
Contraction and milk release
Where do releasing factors come from and what do they act on
Hypothalamus, anterior pituitary
Stimulate release of corresponding hormone
Adrenocorticotropic hormone (ACTH) Source, target, function
Anterior pituitary
Adrenal cortex
Secretion of adrenal hormones
Follicle Stimulating Hormone (FSH)
Source, target, function
Anterior pituitary
Ovaries and tests
Growth of follicles / seminiferous tubules
Luteinizing hormone (LH) Source, target, function
Anterior pituitary
Ovaries and testes
Production of estrogen, progesterone and testosterone
Prolactin (PRL)
Source, target, function
Anterior pituitary
Ovaries and breasts
Milk production and secretion of estrogen and progesterone from ovaries
Thyroid Stimulating Hormone (TSH)
Source, target, function
Anterior pituitary
Thyroid
Stimulate secretion of thyroid hormones
Growth Hormone (GH) / Somatotropin Source, target, function
Anterior pituitary
General
Bone and tissue growth
Release of insulin-like growth factor
Lipotropin (LPH)
Source, target, function
Anterior pituitary
Adipocytes
Fatty acid release
Triiodothyronine (T3) and Thyroxine (T4)
Source, target, function
Thyroid
General
Metabolism, growth, development
Calcitonin
Source, target, function
Thyroid
Osteoclasts
Inhibits bone resorption
Lowers blood calcium
Raises blood phosphorus
Parathyroid Hormone (PTH) Source, target, function
Parathyroids
Osteoclasts, kidneys, intestines
Stimulates bone resorption
Raises blood calcium
Lowers blood phosphorus
Aldosterone
Source, target, function
Adrenal cortex
Kidneys
Sodium resorption
Cortisol
Source, target, function
Adrenal cortex
Muscles, liver, general
Protein and carbohydrate metabolism
Raises blood glucose
Dehydroepiandrosterone (DHEA)
Source, target, function
Adrenal cortex
Uterus, general
Contractions
Stimulate sex drive
Epinephrine
Source, target, function
Adrenal medulla
Muscle, liver, heart
Raises metabolic rate
Increases blood glucose
Increases heart rate
Nor-epinephrine
Source, target, function
Adrenal medulla
Arterioles, live, heart
Vasoconstrictor
Lipid metabolism
Melatonin
Source, target, function
Pineal gland
Gonads, pigment cells
Regulates biorhythms
Glucagon
Source, target, function
Pancreatic alpha cells
Liver, adipocytes
Raises blood glucose
Insulin
Source, target, function
Pancreatic beta cells
Liver, adipocytes, general
Lowers blood glucose
Estrogens (estradiol, estrone)
Source, target, function
Ovaries
Uterus, general
Develop and maintain female characteristics
Progesterone
Source, target, function
Ovaries
Uterus, general
Develop uterine lining
Testosterone
Source, target, function
Testes
General, reproductive organs
Develop and maintain male characterisitics, spermatogenesis
Relaxin
Source, target, function
Ovaries and placenta
Pelvic ligaments
Relaxes pelvic ligaments
Inhibin
Source, target, function
Testes
Anterior pituitary
Inhibits release of FSH
Chorionic Gonadotropin (HCG) Source, target, function
Placenta
Anterior pituitary
Release of FSH and LH
Gastrin
Source, target, function
Stomach antrum
Stomach
HCl and pepsin secretion
Pancreatic secretions
Secretin
Source, target, function
Duodenal mucosa
Pancreas
Secretion of pancreatic juices
Cholecystokinin
Source, target, function
Duodenal mucosa
Gallbladder
Release of bile