Guyton And Hall Questions Flashcards
What is a neuroendocrine secretion?
Secretion of chemical messengers from neurons to blood.
Example of a neuroendocrine secretion?
Oxytocin. Stimulates breast and uterus.
Where are thyroid and peptide hormones stored?
In their endocrine producing glands.
Where are steroids stored and what is an example?
Not in endocrine producing glands. Like aldosterone, which is stored in adrenal cortex.
What is a paracrine secretion?
Cell secretions that diffuse into extra cellular fluid to affect neighboring cells.
What does aromatase do?
Cause conversion of testosterone to estradiol.
Describe peptide hormones.
Water soluble but not highly bound by plasma proteins, resulting in short half lives. Produce biological effects by binding to cell membrane receptors. Stored in secretion granules in endocrine producing cells.
Describe ADH.
A neurohypophyseal peptide hormone unbound by plasma proteins. Increases permeability of collecting tubules and ducts to water and not sodium, decreases water secretion and increasing urine concentration and diluting plasma.
Describe steroid and thyroid hormones.
Highly bound to plasma proteins.
What are ADH and oxytocin?
Peptides containing nine amino acids.
Why do peptide hormones have a more rapid onset than steroid and thyroid hormones?
Protein synthesis is not required.
Where is ADH synthesized?
Supraoptic and paraventricular nuclei of hypothalamus.
Where is inhibitory hormone somatostatin synthesized and stored?
Thalamus.
Where are TSH and LH synthesized and stored?
Anterior pituitary gland.
Where is ADH synthesized and stored?
Synthesized in hypothalamus but stored in posterior pituitary gland.
Where is somatomedin (IGF-1) synthesized?
Liver.
What is the function of testosterone in male embryo?
Formation of male sex organs.
What happens if FSH is blocked to serotoli cells of seminiferous tubules?
Sperm production inhibited.
Why would there be high testosterone in a female embryo?
Embryo has male genitalia. Mother could have adrenal tumor synthesizing testosterone at a high and uncontrolled rate.
Explain secretion of inhibin by Sertoli cells.
Sertoli cells secrete inhibin at a rate proportional to sperm cell production rate. Inhibits anterior pituitary FSH secretion.
What does FSH do in male reproductive system?
Binds to receptors of Sertoli cells to stimulate sperm production.
What does a high potassium diet result in?
High circulating levels of aldosterone. Potassium is a potent stimulus for aldosterone.
What is greater for T4 than T3?
Secretion rate, plasma concentration, half-life, onset of action
What has a greater affinity for T3 than T4?
Nuclear receptors
What occurs due to iodine deficiency?
Increased metabolic rate.
Increased sweating.
Increased nervousness.
Tachycardia.
HYPERTHYROIDISM.
What is needed to synthesize thyroid hormones?
Iodine.
How are goiters formed?
Iodine deficiency. Plasma levels increase TSH release and stimulate follicular cells to increase thyroglobulin synthesis.
What secretes somatostatin?
Delta cells of the pancreas.
What does somatostatin do?
Inhibits secretion of insulin and glucagon.
What produces insulin?
Pancreatic beta cells.
What produces glucagon?
Pancreatic alpha cells.
What stimulates insulin secretion and what inhibits it?
Stimulated by amino acids and glucose, hyperglycemia.
Inhibited by somatostatin.
What happens as a result of insulin binding to a receptor?
Tyrosine kinase is activated which results in increased synthesis of fats, proteins, and glycogen.
Describe role of GH in glucose homeostasis?
Anabolic and promotes protein synthesis through IGF-1 AKA somatomedin C.
Describe role of cortisol in glucose homeostasis?
Decreases protein synthesis in extrahepatic cells such as in muscle due to Glut4 transporter being blocked.
What do GH and cortisol both do in glucose homeostasis?
Impair glucose uptake in peripheral tissues and increases plasma glucose concentration.
Also mobilizes triglycerides from fat stores.
Why does liver function imperfectly in first few weeks of life?
Glucose concentration in blood is unstable and falls to low levels within a few hours of feeding.
What happens after consuming amino acids?
GH and glucagon secreted in stimulated
What happens when glucagon secretion increases?
Blood glucose concentration increases and opposes the effect’s of insulin=hypoglycemia.
What stimulates glycogenolysis in liver?
Glucagon. Has no effect on muscle.
What impairs glucose uptake by muscle?
Cortisol.
Increases levels of glucagon and cortisol result in what?
Gluconeogenesis.
An increase in parathyroid hormone concentration results in what?
Stimulation of existing osteoclasts.
Decreased calcium reabsorption and increased calcium excretion rate in urine is due to what?
Reduction in hormone concentration
How to calculate Nernst Ion Potential?
E(ion) = +/-61 log (intracellular con/extracellular conc)
What is post tetanic facilitation?
Neuron is more easily excited after a long period of activity due to a buildup of calcium in presynaptic membrane due to prior neuronal activity.
Where are preganglionic neurons located?
In interomediolateral cell column (lateral horn) T1-L2
Which preganglionic parasympathetics that contribute to descending colon & rectum innervate?
S2 and S3
Where are nicotinic cholingergic receptors found?
@synapses between preganglionic and postganglionic sympathetic neurons
What innervates sweat glands and piloerector smooth muscle of hairy skin?
By population of cholinergic postganglionic sympathetic neurons
What stimulates nasal, lacrimal, salivary, and GI glands?
Cholinergic postganglionic parasympathetic neurons
If there is a decrease in postganglionic sympathetic neuron activity what results ?
Vasodilation of systemic arterials
Prolonged contraction of skeletal muscle results in what?
Hypertrophy due to synthesis of contractile proteins
Increase in calcium concentration in skeletal muscle results in what?
Skeletal muscle can contract. Contraction uses less energy and contraction lasts longer. Can stimulate contraction without needing action potential.
