Ch 5 Cell Signaling and the Hormonal Responses to Exercise Flashcards
The endocrine system differs from the nervous system in that it releases _____ into the blood to circulate to tissues.
enzymes
hormones
histamines
coagulation factors
hormones
The effect of a hormone on a tissue is directly related to the _____.
rate of blood supply to the target tissue
hormone concentration in the plasma
mode of transport of the hormone
function of the target tissue
hormone concentration in the plasma
An increase in _____ levels decreases insulin secretion.
epinephrine and norepinephrine (sympathetic nervous system activity)
An increase in _____ levels increases insulin secretion.
plasma glucose and amino acids
True or false: The magnitude of the excitatory input by itself determines whether there will be an increase or decrease in insulin secretion from the pancreas.
False; the magnitude of inhibitory vs excitatory input determines whether there will be an increase or decrease in the secretion of insulin
The _____ can metabolize a variety of hormones or excrete them in their free (active) form.
kidneys
Identify a hormone that is transported bound to a plasma protein.
Thyroxine (and steroid hormones) are transported, bound to a plasma protein
Unlike the endocrine system, nerves use ___ to relay messages from one nerve to another
Nerves use NEUROTRANSMITTERS;
Endocrine system use hormones!
True or false: The effect a hormone exerts on a tissue is independent of the number of active receptors to which it can bind.
FALSE; The effect a hormone exerts on a tissue is proportional (directly related) of the number of active receptors to which it can bind.
Chronic exposure of a tissue to a low concentration of a hormone may lead to _____ of receptors, where the tissue becomes very responsive to the available hormone.
up-regulation
endocytosis
down-regulation
disaggregation
up-regulation
Which of the following conditions increases insulin secretion from the pancreas?
Decrease in levels of omega-3 fatty acids
Decrease in blood pressure
Elevation of epinephrine and norepinephrine
Elevation of plasma glucose and amino acids
Elevation of plasma glucose and amino acids
What is down-regulation?
Receptor number may decrease when exposed to a chronically elevated level of a hormone, resulting in a diminished hormonal response for a given concentration
What is up-regulation?
Chronic exposure to a low concentration of a hormone which leads to an increase in receptor number with the tissue becoming very response to the available hormone
What is saturation?
A situation in which the concentration of a hormone is so high that all receptors are bound to the hormone
Inactivation of hormones can take place in the _____, the major site for hormone metabolism.
liver
Steroid hormones easily diffuse through the cell membrane due to their __ nature and bind to a protein receptor in the cell cytoplasm to form the steroid-receptor complex
lipid-like
A hormone must be in the _____ form in order to interact with the receptor and exert its effect on a cell.
free
lipid-bound
protein-bound
inhibited
free
Many hormones exert their effects by binding to a receptor on the cell surface and activating a _____ located in the membrane of a cell.
G-Protein (the link between the hormone-receptor interaction on the surface of the membrane and the subsequent events inside the cell)
_____ is known to increase phosphodiesterase activity by allowing cyclic AMP to exert its effect for a longer period.
caffeine
What is a result of phospholipase C when it is activated by G PROTEIN?
Causes phosphatidylinositol (PIP2) to be broken down into inositol triphosphate (IP3) and diacylglycerol (DAG)
Which of the following glands is located at the base of the brain?
pituitary gland
What is the substrate for the formation of cyclic AMP?
GDP
GTP
AMP
ATP
ATP
What is the enzyme that inactivates and converts cyclic AMP to 5’ AMP?
phosphodiesterase
What hormone directly stimulates the breast tissue to produce milk?
prolactin
_____ is a membrane-bound enzyme that is activated by a G protein and hydrolyzes phosphatidylinositol into two intracellular molecules.
Phospholipase C
Phosphodiesterase
Protein kinase A
Phosphorylase
phospholipase C
Growth hormone (GH) and insulin-like growth (IGFs) stimulate the synthesis of new protein and long-bone growth
True
What does insulin bind to, that resides outside the cell, in order to bring about its effects in a cell?
tyrosine kinase receptor’s alpha subunits
The posterior pituitary hormones are produced in the
hypothalamus