123 Questions
What is the primary function of the deiodinase enzyme in the thyroid hormone synthesis process?
To convert T4 to T3
What is the significance of iodine in the synthesis of thyroid hormones?
It is incorporated into the structure of thyroid hormones
Where is thyroglobulin synthesized in the thyroid follicular cells?
Rough endoplasmic reticulum and Golgi apparatus
What is the ratio of T4 to T3 produced by the thyroid gland?
9:1
What is the purpose of storing thyroid hormones in the follicular lumen?
To store thyroid hormones until they are needed
What is the primary mechanism by which thyroid hormones regulate protein synthesis in target cells?
By increasing the transcription of specific genes
What is the approximate daily requirement of iodine in the form of iodides to form normal quantities of thyroxine?
1 milligram per week
What is the primary source of dietary iodide?
Fish, seafood, and seaweed
What is the ionic state of iodine?
Iodide
What is the net result of thyroid hormone action on target cells?
A generalized increase in functional activity
What is the primary factor that influences the rate of iodide trapping by the thyroid gland?
Concentration of TSH
Under conditions of severe dietary iodide deficiency, what is the ultimate effect on thyroid hormone synthesis?
Decreased synthesis of T3 and T4
What is the role of deiodinase enzymes in thyroid hormone synthesis?
To convert T4 into T3
Which of the following statements about propylthiouracil (PTU) is true?
PTU inhibits the activity of deiodinase enzymes
What is the normal concentration ratio of iodide in the thyroid gland compared to the blood?
30 times
What is the primary constituent of colloid in the thyroid gland?
Thyroglobulin
Which cells in the thyroid gland are responsible for synthesizing and secreting thyroid hormones?
Epithelial cells
What is the effect of thyroid hormones on the body?
They affect virtually every organ system in the body
What is the function of C cells in the thyroid gland?
To regulate plasma calcium ion concentration
What is the structure of the thyroid gland composed of?
A large number of follicles
What is the primary regulator of thyroid hormone secretion?
Thyroid stimulating hormone (TSH)
What is the effect of TSH on the thyroid gland?
Increased activity of the iodide pump
What is the effect of triiodothyronine (T3) on the hypothalamic-pituitary negative feedback control system?
Inhibits TSH secretion
What is the characteristic of thyroid hormones in terms of their structure and action?
Peptide hormones with steroid-like actions
What is the primary function of thyrotropin-releasing hormone (TRH)?
Stimulates TSH secretion from the pituitary gland
What is the effect of elevated TSH levels on thyroid follicular cells?
Hypertrophy and hyperplasia
What is the primary manifestation of hypothyroidism?
Lethargy and fatigue
What is the effect of propylthiouracil (PTU) on thyroid hormone synthesis?
Inhibits the interaction between iodine and peroxidase with thyroglobulin
What is the primary function of thyroid hormone in the body?
Regulation of body metabolism
What is the effect of hypothyroidism on the body?
Slowing of mental and physical performance
What is the effect of thyroid hormones on basal metabolic rate?
Increase
What is the effect of thyroid hormones on bone formation?
Stimulate bone formation
How do thyroid hormones affect carbohydrate metabolism?
Stimulate glucose uptake
What is the effect of thyroid hormones on fat metabolism?
Stimulate lipid mobilization
What is the effect of thyroid hormones on plasma cholesterol levels?
Decrease
What happens to plasma cholesterol levels in hypothyroidism?
Increase
What is the effect of thyroid hormones on oxygen consumption?
Increase
How do thyroid hormones affect cardiovascular and respiratory systems?
Increase blood flow and oxygen delivery
What is the effect of thyroid hormones on liver fats?
Increase
What is the effect of thyroid hormones on nutrient metabolism?
Increase metabolism
What is the primary effect of thyroid hormones on bone formation?
They act synergistically with growth hormone and somatomedins to promote bone formation
What is the effect of thyroid hormones on the cardiovascular system?
They increase blood flow and oxygen delivery to the tissues
What is the primary effect of thyroid hormones on cellular metabolic activity?
They increase glucose uptake and glycolysis in cells
What is the effect of thyroid hormones on metabolic rate and energy production?
They increase basal metabolic rate (BMR) and energy production
What happens to the concentration of free fatty acids in the plasma in response to thyroid hormones?
It increases significantly
What is the effect of thyroid hormones on oxygen consumption in the tissues?
They increase oxygen consumption
What is the primary effect of thyroid hormones on skeletal muscle?
Reacts with vigor
What is the primary regulator of thyroid hormone secretion in the hypothalamic-pituitary negative feedback control system?
Thyroid Releasing Hormone (TRH)
What is the primary effect of thyroid hormones on the metabolic rate?
Greatly accelerated rate of utilization of foods for energy
What is the effect of thyroid hormones on heart rate and cardiac output?
Increases heart rate and cardiac output
What is the effect of thyroid hormones on mitochondria?
Increased number and activity
What is the primary mechanism by which thyroid hormones stimulate cellular metabolic activity?
Stimulating energy metabolism
How do thyroid hormones affect the transport of ions through cell membranes?
Increase the transport of sodium and potassium ions
What is the effect of thyroid hormones on basal metabolic rate?
Increases basal metabolic rate
What is the effect of thyroid hormones on protein synthesis and catabolism?
Increased protein synthesis and catabolism
What is the primary effect of thyroid hormones on growth and development prior to adulthood?
Stimulates bone growth and development
What is the duration of action of thyroid hormones after injection of a large quantity of thyroxine?
Delayed onset, maximum effect in 10-12 days
What is the half-life of thyroid hormones?
About 15 days
What is the location where hormones synthesized by hypothalamus are released into?
Hypothalamo-hypophyseal portal system
What is the function of the paraventricular nuclei (PVN) in the hypothalamus?
Produces oxytocin
What is the characteristic of anterior pituitary hormones?
Are peptides or polypeptides
What is the result of the negative feedback control in the hypothalamic-pituitary axis?
Decreases the production of anterior pituitary hormones
Which hormone is produced by the somatotrophs in the anterior pituitary?
Growth hormone (GH)
What is the proportion of the pituitary gland composed of nervous tissue?
¼
What is the function of the hypothalamo-hypophyseal portal system?
Transport hormones from hypothalamus to anterior pituitary
What is the primary function of oxytocin in the context of lactation?
Stimulation of smooth muscle contraction in the breast to cause ejection of milk
What is the effect of antidiuretic hormone (ADH) on the kidneys?
Decreased urine output
What is the role of the hypothalamic-hypophyseal portal system?
To deliver hypothalamic hormones to the anterior pituitary
What is the effect of growth hormone-releasing hormone (GHRH) on the anterior pituitary?
Stimulation of growth hormone secretion
What is the function of prolactin-inhibiting hormone (PIH) on the anterior pituitary?
Inhibition of prolactin secretion
What is the role of corticotropin-releasing hormone (CRH) in the hypothalamic-pituitary axis?
Stimulation of adrenocorticotropic hormone (ACTH) secretion
What is the effect of thyrotropin-releasing hormone (TRH) on the anterior pituitary?
Stimulation of thyroid-stimulating hormone secretion
What is the primary function of the hypothalamus in terms of maintaining homeostasis?
Maintaining chemical constancy and temperature of the internal environment
What is the term for the extracellular fluid environment that surrounds the cells and tissues?
Internal Mileau
Which of the following is a function of the posterior pituitary?
Producing antidiuretic hormone (ADH) and oxytocin
What is the term for the connection between the hypothalamus and the posterior pituitary?
Hypothalamohypophyseal tract
Which of the following nuclei produces antidiuretic hormone (ADH)?
Supraoptic nuclei (SON)
What is the primary function of the hypothalamus in terms of emotional and instinctual behavior?
Regulating emotional responses
What is the term for the regulation of body temperature by the hypothalamus?
Temperature regulation
Which of the following is a function of the anterior pituitary?
Regulating growth and development
What is the term for the physiological process of maintaining protective stability for the tissues and organs?
Homeostasis
What is the primary function of the hypothalamus-pituitary complex?
To regulate the synthesis and secretion of hormones from other glands
How does the hypothalamus control the pituitary gland?
Through both neural and hormonal mechanisms
What is the significance of the connections between the hypothalamus and pituitary gland?
They regulate the synthesis and secretion of hormones from other glands
What is the role of the hypothalamus in the endocrine system?
To regulate the synthesis and secretion of hormones from other glands
How do hypothalamic neuropeptides reach the posterior pituitary?
Through the hypothalamic-hypophyseal portal system
What is the primary function of the hypothalamus-pituitary complex in the endocrine system?
To regulate the synthesis and secretion of hormones from other glands
What is the significance of the hypothalamus receiving neural inputs from many areas of the brain?
It allows for the integration of various neural signals to regulate hormone synthesis and secretion
What is the primary function of the hypothalamus-pituitary complex in the endocrine system?
To regulate the synthesis and secretion of hormones of other glands
What is the mechanism by which the hypothalamus controls the pituitary gland?
Through both neural and hormonal mechanisms
What is the role of releasing hormones in the hypothalamus-pituitary complex?
To stimulate the synthesis of hormones in other glands
What is the significance of the anatomic connections between the hypothalamus and the pituitary gland?
They enable the hypothalamus to control the pituitary gland
What is the primary route of transport of hypothalamic neuropeptides to the posterior pituitary?
Through the neural connections between the hypothalamus and pituitary gland
What is the role of the hypothalamus in the regulation of the endocrine system?
It regulates the synthesis and secretion of hormones of other glands
What is the mechanism by which the hypothalamus receives information from other parts of the brain?
Through the neural connections between the hypothalamus and other parts of the brain
What is the primary function of the hypothalamus in maintaining homeostasis?
Maintaining the chemical constancy and temperature of the internal environment
What is the primary function of the hypothalamic-pituitary complex in the regulation of the endocrine system?
To regulate the synthesis and secretion of hormones of other glands
What is the term for the extra-cellular fluid environment, interstitial fluid, and its physiological capacity to ensure protective stability for the tissues and organs of multicellular organisms?
Internal Mileau
Which nuclei in the hypothalamus produce oxytocin?
Paraventricular nuclei
What is the function of the hypothalamohypophyseal tract?
Releasing antidiuretic hormone and oxytocin into the bloodstream
What is the function of the posterior pituitary?
Storing and releasing hormones produced by the hypothalamus
What is the function of the anterior pituitary?
Producing hormones that regulate growth and development
What is the role of the hypothalamus in regulating body rhythms?
Regulating sleep and wake patterns
What is the term for the collection of nerve axons whose cell bodies are located in the hypothalamus?
Neurohypophysis
What is the primary function of the hypothalamus in regulating emotional and instinctual behavior?
Regulating emotional and instinctual behavior through the limbic system
What is the unique characteristic of cells in the anterior pituitary gland that receive high concentrations of hypothalamic hormones?
They are directly connected to the hypothalamus through the hypophyseal portal system
What is the function of the paraventricular nuclei (PVN) in the hypothalamus?
To synthesize and release oxytocin
Which hormone is synthesized by the somatotrophs in the anterior pituitary gland?
Growth hormone (GH)
What is the primary mechanism of control for the anterior pituitary hormones?
Negative feedback control
What is the characteristic of the hormones synthesized by the anterior pituitary gland?
They are all peptides or polypeptides
What is the role of the hypothalamo-hypophyseal portal system?
To transport hypothalamic hormones to the anterior pituitary gland
What is the function of the corticotrophs in the anterior pituitary gland?
To synthesize and release adrenocorticotropic hormone (ACTH)
What is the primary function of the thyrotrophs in the anterior pituitary gland?
To synthesize and release thyroid-stimulating hormone (TSH)
What is the primary function of the gonadotrophs in the anterior pituitary gland?
To synthesize and release follicle-stimulating hormone (FSH) and luteinizing hormone (LH)
What is the primary function of oxytocin in the uterus during delivery?
To stimulate uterine contractions
What is the effect of antidiuretic hormone (ADH) on the kidneys?
It decreases urine output and increases fluid intake
What is the primary function of hypophysiotropic hormones?
To regulate the secretion of anterior pituitary hormones
What is the primary mechanism of the hypothalamic-hypophyseal portal system?
It transports hormones from the hypothalamus to the anterior pituitary
What is the significance of the hypothalamic-hypophyseal portal system?
It allows the hypothalamic hormones to be delivered to the anterior pituitary directly and in high concentration
What is the effect of antidiuretic hormone (ADH) on blood vessels?
It causes vasoconstriction
What is the function of growth hormone–releasing hormone (GHRH)?
It regulates the release of growth hormone
What is the function of somatostatin?
It inhibits the release of growth hormone
What is the primary function of prolactin-releasing hormone (PRH)?
It regulates the release of prolactin
This quiz covers the structure and function of thyroglobulin, its synthesis and storage in the thyroid follicular cells, and its role in thyroid hormone synthesis.
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