Midterm II Review Flashcards
How do negative anions affect thyroid hormone synthesis? Provide examples of negative anions.
- Block the active transport of iodine by the Na+/I- symporter
- Bromide, nitrite, perchlorate
How does propylthiouracil affect thyroid hormone synthesis?
Blocks the iodination of thyroglobulin
How do goitrogens affect thyroid hormone synthesis?
Block thyroid peroxidase
Describe three reasons that explain the physiological importance of deiodinases.
- Permits local tissue and cell modulation of thyroid hormones
- Aids in adaptations to change, including iodine deficiency or chronic illness
- Regulates thyroid actions during early development
What is the function of the a2-receptor for thyroid hormones?
Acts as an inhibitor
What is the location of the B2-receptor for thyroid hormones?
Anterior pituitary and brain
Provide three examples of causes of congenital hypothyroidism.
- Maternal iodine deficiency
- Fetal thyroid dysgenesis
- Inborn errors of thyroid hormone synthesis
- Maternal anti-thyroid antibodies cross the placenta
- Fetal hypopituitary hypothyroidism
What enzyme converts cholesterol to pregnenolone?
P450scc
What are functions of enkephalins?
- Block neurotransmission
- Act as an endogenous analgesic
What are the four immediate short-term responses to crises?
1) Mobilization of glucose reserves
2) Changes in circulation
3) Increases in heart and respiratory rates
4) Increased energy use by all cells
What are the four long-term metabolic adjustments to crises (resistance phase)?
1) Mobilization of remaining energy reserves (lipids and amino acids)
2) Conservation of glucose (peripheral tissue breaks down lipids to obtain energy)
3) Elevation of blood glucose concentrations (gluconeogenesis)
4) Conservation of salts and water, as well as loss of potassium and H+
What are four causes of the exhaustion phase?
- Exhaustion of lipid reserves
- Inability to produce glucocorticoids
- Failure of electrolyte balance
- Cumulative structural or functional damage to vital organs
What is the potency of the a1 receptor of catecholamines with Gq action?
NE > E
What is the potency of the a1 receptor of catecholamines with Gi action?
E > NE
What is the potency of the B1 receptor of catecholamines with Gs action?
NE > E