The Endocrine System IV (Lecture 17) Flashcards
True or False: There is little variation in rate of secretion of thyroid hormone.
True
______ synthesize thyroid hormones, and hormones are stored in the ______ until secreted.
Follicular cells, colloid
______ is a protein that is a precursor for thyroid hormones that contains tyrosine residues locate in the colloid
Thyroglobulin
______ is actively transported from blood into colloid and added to thyroglobulin to form thyroid hormones.
Iodide
Linking two DIT groups = a ______, linking a DIT and a MIT group = a ______.
T3, T4
True or False: T3 (triiodothyronine) is the most abundant form produced.
False, T4 (thyroxine) 90%
Out of T3 and T4 which one is more potent at target tissues.
T3
True or False: T4 Provides long loop negative feedback.
True
How does activation work in the synthesis and secretion of thyroid hormones.
Conversion by the liver, kidneys, or target tissues
T4 converted to T3
How does the TRH feedback loop work?
TRH secretion from hypothalamus
TSH from anterior pituitary
T3 and T4 secretion from thyroid gland (T4 makes negative feedback loop)
T4 converted to T3 in liver kidney and target cells
True or False: Stimulus for TRH, and thus TH, is exposure to cold temperatures.
True
True or False TRH is prominement in adults and not infants.
False, vice versa
Inhibition of TRH, and thus TH,
is by ______.
Stress
True or False: Thyroid hormones are lipophilic and capable of crossing membranes
True
True or False: Thyroid hormones Alter rates of transcription of mRNA from DNA, and thus protein synthesis
and alterations take hours to day to exert.
True
Primary action of TH is a ______ effect.
calorigenic
WHat is the graph of prolonged effect on basal metabolic rate caused by thyroxine over time
Increase, spike at 10 days, the gradual decrease
What 5 things occur during the TH calorgenic effect?
Raise the body’s BMR
Increase in metabolism in most tissues of the body, exceptions include the brain, spleen, and gonads
Increase rate of oxygen consumption
Increase rate of energy expenditure at rest
Increase heat generation
Calorigenic effects
Increases rate of Na+/K+ pump
Higher rates of fuel oxidation and ATP production
Increases in heat production
Increases number and size of mitochondria
Increases oxidative phosphorylation enzymes
Higher energy mobilization
Enhances glycogenolysis, proteolysis, and lipolysis
Promotes gluconeogenesis and ketone synthesis
Promotes synthesis of β adrenergic receptors (for normal growth and development and maintenance)
______ is when the thyroid gland is increased in size, hyperplasia caused by autoimmune or tumor induced
Hyperthyroidism
What are the symptoms of hyperthyroidism?
protrusion of eyeballs, weight loss, irregular heartbeat
______ is resulting from destruction of the thyroid gland caused by a autoimmune disease.
Hypothyroidism
Symptoms of hypothyroidism include
fatigue, extreme muscular sluggishness, slowed heart rate, increased body weight, constipation, mental sluggishness
What is the cortisol secretion feedback loop?
Stress, circadian rhythm lead to increased CRH secretion in hypothalamus
ACTH then is secreted from the anterior pituitary
Cortisol is secreted from the adrenal cortex
