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
Which hormone reduces water loss from the body?
antidiuretic hormone
The hormones move down the axon to blood vessels in the posterior hypothalamus where they are discharged into the _____.
general circulation
pulmonary circulation
primordial circulation
intervillous circulation
general circulation
What gland secretes the hormones follicle stimulating hormone (FSH), luteinizing hormone (LH), thyroid-stimulating hormone (TSH) and growth hormone (GH)?
anterior pituitary gland
What are the two iodine-containing hormones synthesized by the thyroid gland?
triiodothyronine (T3) and thyroxine (T4)
What are the functions of the growth hormone (GH) and insulin-like growth factors (IGFs)?
- stimulate tissue uptake of amino acids
- synthesis of new protein
- synthesis of long-borne growth
What does the posterior pituitary gland provide a storage site for?
oxytocin and the antidiuretic hormone
What is calcitonin?
Secreted by the thyroid gland, calcitonin is involved in a minor way in the regulation of plasma calcium ions
What is the antidiuretic hormone?
it reduces water loss from the body; ADH favors the reabsorption of water from the kidney tubules back into the capillaries to MAINTAIN BODY FLUID
What two major stimuli may cause an increase secretion of antidiuretic hormone (ADH)?
- high plasma osmolality (low water concentration) that can be caused by excessive sweating without water replacement
- low plasma volume, which can be due to blood loss or to inadequate fluid replacement
SUMMARY: high plasma concentration due to excessive sweating without drinking water AND low plasma volume which could be due to loss of blood
How does calcitonin lower the levels of calcium in the plasma?
by initiating the process of chondrogenesis
by enhancing calcium reabsorption in the kidney tubules
by increasing the production of activated vitamin D
by blocking release of calcium from the bone
by blocking release of calcium from the bone
NOTE: enhancing calcium reabsorption in the kidney tubules is the function of antidiuretic hormone
What is the primary hormone involved in plasma Ca2+ regulation?
the parathyroid hormone
How does the parathyroid hormone increase Ca2+ levels in the plasma?
by stimulating the bone to release Ca2+ into the plasma
What is the primary stimulus for the release of thyroid hormones into circulation?
thyroid-stimulating hormone
What secretes the catecholamines epinephrine and norepinephrine?
adrenal medulla
NOTE: epinephrine and norepinephrine ARE catecholamines
The adrenal medulla is part of what system?
the sympathetic nervous system
What is the adrenal gland made up of (what glands make up the adrenal gland)?
the adrenal medulla (which secretes the catecholamines (epinephrine and norepinephrine)) and the adrenal cortex (which secretes steroid hormones)
What does the adrenal cortex secrete compared to the adrenal medulla?
steroid hormones (contains aldosterone, cortisol, and sex steroids: androgens and estrogen)
NOTE: adrenal medulla secretes epinephrine and norepinephrine
Of the adrenal medulla’s hormonal secretions, which one affects receptors in the cardiovascular and respiratory systems, GI tract, liver, and other endocrine glands?
epinephrine
Renin converts angiotensinogen to angiotensin I, which is in turn converted to _____ by the angiotensin converting enzyme (ACE).
angiotensin II
angiotensin IV
angiotensin III
angiotensin V
angiotensin II
What is the primary glucocorticoid secreted by the adrenal cortex?
cortisol
Epinephrine and norepinephrine are involved in the _____.
modulation and inhibition of action potentials in neurons
release of digestive enzymes from the pancreas
stimulation of red blood cell development in the bone marrow
maintenance of blood pressure and plasma glucose concentration
maintenance of blood pressure and plasma glucose concentration
What is an example of a mineralocorticoid; give its function
aldosterone: maintenance of Na and K concentrations in plasma
Cortisol promotes the breakdown of tissue protein to form _____, which are used by the liver to synthesize new glucose.
free fatty acids
atrial natriuretic hormones
amino acids
glycerol
amino acids
What is the General Adaptation Syndrome (GAS)?
The response when a stressful event (like burns, bone breaks, and heavy exercise) led to predictable increases in ACTH and cortisol
What are the 3 stages of GAS (General Adaptation Syndrome)?
1) the alarm reaction (involves cortisol secretion)
2) the stage of resistance (where repairs are made)
3) the stage of exhaustion (repairs are not adequate and sickness or death results)
Hormones are released from groups of cells in the endocrine portion of the pancreas called _____.
Leydig cells
the ascending limb of the loop of Henle
the islets of Langerhans
Sertoli cells
the islets of Langerhans
Glucagon is secreted by the _____ cells in the islets of Langerhans.
delta
beta
epsilon
alpha
alpha
How does cortisol contribute to the maintenance of plasma glucose during long-term fasting and exercise?
- by stimulating liver enzymes involved in the metabolic pathway leading to glucose synthesis
- by stimulating the mobilization of free fatty acids from the adipose tissue
- promote the breakdown of tissue protein (by inhibiting protein synthesis) to form amino acids which are then used by the liver to form new glucose (gluconeogenesis)
- block the entry of glucose into tissues, forcing those tissues to use more fatty acids as fuel
What secretions of the pancreas include digestive enzymes and bicarbonate, which are secreted into ducts leading to the small intestine?
exocrine
_____ secretion is controlled by the interstitial cell stimulating hormone (ICSH) produced in the anterior pituitary.
testosterone
estrogen
progesterone
androstenedione
testosterone
What is insulin’s best-known function?
facilitated diffusion of glucose across the cell membrane
Testosterone is an anabolic steroid because it stimulates?
fatty acid breakdown
glycogenesis
lipogenesis
protein synthesis
protein synthesis
What is an anabolic steroid?
a prescription drug that has anabolic (GROWTH-STIMULATING) characteristics similar to that of the male androgen testosterone
What secretion increases in response to low plasma glucose concentration?
glucagon
What is the function of glucagon?
- stimulates the mobilization of glucose from liver stores (glycogenolysis)
- stimulates free fatty acids from adipose tissue using the adenylate cyclase second messenger mechanism
How is the plasma glucose concentration maintained? There are four processes, list them.
1) mobilize existing glucose from liver glycogen stores to maintain the plasma glucose level
2) mobilize plasma FFA from adipose tissue to increase the use of fat as a fuel and spare plasma glucose
3) synthesize new glucose in the liver (gluconeogenesis) from amino acids, lactate, and glycerol to have it available as needed
4) block glucose entry into cells to force the cell to use fat as a fuel, and thus spare plasma glucose
Thyroid hormones allow other hormones to exert their full effect by _____.
increasing ATP synthesis
stimulating adenylate cyclase activity
influencing the number of receptors on the target cell surface
altering the structural conformation of other hormones
influencing the number of receptors on the target cell surface
Growth hormone helps ___.
increase glucose uptake by tissue
increase free fatty acid mobilization
decrease gluconeogenesis in the liver
decrease glycogenolysis in the muscle tissue
increase free fatty acid mobilization
What hormone seems to be more responsive than others to changes in plasma glucose concentrations?
epinephrine
Thyroid hormones are important in establishing the overall _____.
metabolic rate
electrolyte balance
pulse rate
circadian rhythm
metabolic rate
What is the function of epinephrine and norepinephrine?
- mobilization of glucose from the liver
- mobilization of FFA from the adipose tissue
- interference with the uptake of glucose by tissue
What is the role of the hormones glucagon and insulin?
- often referred to as counter-regulatory hormones
- insulin and glucagon exert opposite physiologic actions relative to the mobilization of liver glucose and adipose tissue FFA
_____ causes a very rapid decrease in plasma epinephrine and norepinephrine responses to a fixed exercise bout.
endurance training
anaerobic exercises
balance training
strength exercises
endurance training
