Biochemical Signaling: Hormones Flashcards
Which hormones fuel metabolism?
Pancreatic hormones
Which hormones are responsible for fight or flight?
Epinephrine and norepinephrine
What processes do steroid hormones contribute to?
Metabolic and sexual regulation
What are the chemical messengers in the body that mediate extracellular signals?
Hormones
What does every biochemical signaling pathway include?
1) A signal (the hormone)
2) A receptor protein
3) Mechanism for transmitting hormone binding to cell interior
4) Series of intracellular response that amplify the signal
5) Termination of the signal
What catalyzes the intracellular secondary messengers or chemical changes that amplify the signal?
Kinases and Phosphatases
What are the steps of the signal transduction pathway?
1) Release of the primary messenger (triggered by a stimulus)
2) Reception of primary messenger by membrane recepters.
3) Relay of information from the receptor-ligand complex (extracellular) into the cell by secondary messengers.
4) Activation of effectors that alter the physiological response of the cell.
5) Termination of the signal.
What is the signal molecule often referred to?
the ligand
These are atoms or molecules with electron pairs available; they may be neutral or negatively charged. They binds to a central metal atom to form a complex.
Ligand
What causes changes to concentrations of second messengers that relay information from the ligand-receptor extracellular complex?
Structural changes in membrane receptors
The process of converting the information from a primary messenger into other chemical forms.
Transduction
Which glands in animals synthesize and release hormones into the bloodstream in response to external stimuli?
Endocrine glands
What amino acid are epinephrine and norepinephrine derivatives of?
Tyrosine
What three types of biological molecules are most hormones made of?
1) Polypeptides
2) Amino acid derivatives
3) Steroids
What are the three major roles of hormones in the body?
1) Maintain homeostasis
2) Respond to external stimuli.
3) Cyclic and developmental programs
How do endocrine glands get their hormones to target cells?
Through the bloodstream.
True or false: Endocrine glands are a collection of independent secretory organs.
False
True or false: Endocrine glands form a complex and highly controlled network.
True
What are the 8 major endocrine glands?
1) Hypothalamus
2) Pituitary
3) Parathyroid
4) Thyroid
5) Adrenal
6) Pancreas
7) Kidneys
8) Ovaries and testes
Where are polypeptide hormones synthesized as prohormone?
In ribosomes
Where are polypeptide hormones processed into mature hormones?
Rough endoplasmic reticulum and Golgi bodies
Where are mature polypeptide hormones stored to await stimuli for release?
In secretory granules
By what process are polypeptide hormones released?
Exocytosis
What do Pancreatic Islet hormones control?
Fuel metabolism
How does the bulk of the pancreas function?
As an exocrine gland producing digestive enzymes.
What are trypsin and chymotrypsin?
Digestive enzymes
What is RNase A?
A digestive enzyme
Where are alpha-amylase and Phospholipase A2 procduced? What are they?
Pancreatic Islet; digestive enzymes
How are digestive enzymes moved from the pancreas to the small intestine?
They are secreted through the pancreatic duct.
What is the small portion of the pancreas comprised of small clumps of cells whose function is maintaining energy homeostasis?
Islets of Langerhans
What are the three types of cells in the Islets of Langerhans?
1) alpha-cells
2) beta-cells
3) delta-cells
What life-sustaining hormones do alpha-cells in the Islets of Langerhans secrete?
Glucagon
What life-sustaining hormones do beta-cells in the Islets of Langerhans secrete?
Insulin
What life-sustaining hormones do delta-cells in the Islets of Langerhans secrete?
Somatostatin
What is insulin secreted in response to? Where is it secreted from?
High blood glucose; from beta-cells in the Islets of Langerhans in the pancreas.
What does the secretion of insulin function to do?
Stimulates muscle, liver, and adipose cells to take up glucose and store it by synthesizing glycogen, protein, and fat.
Which hormone is secreted in response to low blood glucose? Where is it secreted from?
Glucagon; from alpha-cells in the Islets of Langerhans
What does the release of glucagon function to do?
1) Causes the liver to break down glycogen and release glucose into circulation.
2) Gluconeogenesis in the liver.
3) Causes adipose tissue to release fatty acids through lipolysis
What is the process of synthesizing glucose from non-carbohydrate sources? Where does this process occur?
Gluconeogenesis
What is the process by which fatty acids are released by adipose tissue?
Lipolysis
What is somatostatin and what does it do? Where is it released from?
It is a hormone that inhibits the release of insulin and glucagon from Islet of Langerhans cells; it is released by the delta-cells of the pancreas and by the hypothalamus.
What two types of tissue comprise the adrenal gland?
1) Medulla (core)
2) Cortex (outer layer)
Where are the adrenal glands located?
Above the kidneys
What two catecholamines are synthesized in the medulla of the adrenal glands?
1) Epinephrine
2) Norepinephrine
What amino acid are epinephrine and norepinephrine synthesized from? Where are they stored?
Tyrosine; Stored in granules awaiting exocytotic release.
What is the only structural difference between epinephrine and norepinephrine?
In epinephrine, the amine group is a secondary amine; in norepinephrine, it is a primary amine (lacks the methyl group of epinephrine).
What are the biological effects of catecholamines mediated by?
alpha- and beta-adrenoreceptors
True or false: alpha and beta recepters generally respond the same to catecholamines.
False; they generally respond differently, and sometimes oppositely.
What are trans-membrane glycoproteins that mediate the effects of catecholamines?
alpha- and beta-adrenoreceptors
What do beta-adrenoreceptors stimulate?
1) Glycogenolysis in liver and skeletal muscle
2) Gluconeogenesis in liver
3) Lypolysis in adipose tissue
4) Relaxation in smooth muscle (in the bronchi and in blood vessels supplying skeletal muscle.
5) Increased heart action
What do alpha-adrenoreceptors stimulate?
1) Smooth muscle contractions in blood vesicles supplying peripheral organs such as skin and kidney.
2) Smooth muscle relaxation in GI tract
3) Blood platelet aggregation
What are the effects of alpha-and beta-adrenoreceptors directed toward?
1) Mobilization of energy resources
2) Preparing the body for action (turning blood on where needed, shutting blood off where not needed).
What causes varying responses of alpha- and beta-receptors?
Varying agonists (substances that bind to receptors and evoke a response) and antagonists (substances that bind to receptors and block agonists).
Where are adrenocortical steroids produced?
Adrenal cortex
Where are glucocorticoids produced?
Adrenal cortex
Which adrenocortical steroids affect carbohydrate, protein, and lipid metabolism (have opposite affect as insulin), influence inflammatory reaction, and influence capacity for coping with stress?
Glucocorticoids
What adrenocortical steroids regulate kidney salt and water excretion?
Mineralocorticoids
What adrenocortical steroids regulate sexual development and maturation?
Androgens and estrogens
How are steroids transported in blood?
By the glycoproteins transcortin and (to a lesser extent) albumin.
True or false: Glucocorticoids and mineralocorticoids are C12 proteins.
False. They are C21 proteins
Which types of steroids and hormones spontaneously pass through the membranes of target cells before binding to receptors? Where do all other hormones bind?
Glucocorticoids, mineralocorticoids, and thyroid hormones. Other hormones bind to cell-surface receptors.
What is the 19-residue polypeptide produced in the pituitary gland?
Growth hormone
What hormone binds to receptors to stimulate growth and metabolism in muscle, bone, and cartilage and to stimulate the liver to produce additional growth factors?
Growth hormone
What is overproduction of growth hormone usually the result of?
A pituitary tumor
Where is growth hormone produced?
The pituitary gland
What results if the overproduction of growth hormone begins before the growth plates have ossified?
Gigantism (with normal body proportions)
Why do people with overproduction of growth hormone before growth plates have ossified continue growing and have abnormally short lives?
The excess GH inhibits testosterone necessary for growth plate ossification, and they continue growing throughout life.
What are the effects of overproduction of growth hormone after growth plates have ossified?
Only soft tissue continues growing; called Acromegaly (enlarged hands, feet, and facial features)
What is the result of growth hormone deficiency?
Dwarfism
How can dwarfism be treated? When can it be treated?
It can be treated before skeletal muscle maturity with injections of human growth hormone (hGH)
True of false; non-human animal GH is not effective in humans.
True
What are the adverse affects of hGH when used for performance enhancement?
Hypertension, joint/muscle pain, and acromegaly
