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
What is the potency of the B2 receptor of catecholamines with Gs action?
E > NE
What is the target of the a1 receptor of catecholamines with Gq action?
Smooth muscle (skin, GI)
What is the target of the a1 receptor of catecholamines with Gi action?
Nerve terminals (synaptic transmission)
What is the target of the B1 receptor of catecholamines with Gs action?
Heart, cerebral cortex
What is the target of the B2 receptor of catecholamines with Gs action?
Lung, smooth muscle, cerebellum
What are the three physiological functions of deiodinases?
1) Permit local tissue and cell modulation of the thyroid hormone
2) Aid in the adaptation to changes, including iodine deficiency or chronic illness
3) Regulate thyroid actions during early development
What may the treatment of hypothyroidism prevent?
- Bone loss
- Cardiomyopathy
- Myxedema
What are symptoms of a myxedema coma?
- Hypoglycemia
- Hypothermia
- Eventually, progressing to a coma and death
How may the antibodies produced in Grave’s disease affect ophthalmopathy?
- Increase in glycosaminoglycans
- Swelling in muscle and connective tissues behind the eyes
- Causes eye bulging
What is the half-life of parathyroid hormone?
Very short (2-4 minutes)
What are the major functions of PTHrP?
- Required for normal development
- Regulator of the proliferation and mineralization of chondrocytes
- Regulator of placental calcium transport
Where is PTHR-1 located?
In bone and kidney tissues
What are possible causes of hyperparathyroidism?
- Radiation exposure
- Lithium
- Associated with the loss of tumour-suppressor genes
What are the functions of CGRP? Where is it made predominantly?
- Made predominantly in the nervous system
- Acts as a neurotransmitter
- May act as a very potent vasodilator via a GPCR
What occurs within intestinal epithelial cells once calcium is uptaken?
1) Binding to myosin/calmodulin complex
2) Move to the bottom of the microvilli
3) Free calcium in cytoplasm is released by exocytosis or pumps
Which tissues contain PNMT?
- Lung
- Kidney
- Pancreas
- Adrenal medulla
What are functions of enkephalins? (2)
1) Block neurotransmitters (similar to morphine)
2) Act as an endogenous analgesic
What are the target tissues of the a1 receptor acting by Gq?
Smooth muscle (skin, GI)
Define immunological tolerance.
Specific unresponsiveness to an antigen that is induced by exposure of lymphocytes to that antigen
Which antibodies are found in 90% of individuals with T1DM?
- Anti-glutamic acid decarboxylase (GAD)
- Anti-IA-2
