39 Questions
What is the primary mechanism by which cortisol increases glucose levels?
Increasing gluconeogenesis and glycogenolysis
How does cortisol antagonize the effects of insulin on glucose metabolism?
By inhibiting insulin's inhibitory effects on gluconeogenesis and glycogenolysis
What is the primary substrate used for gluconeogenesis under the influence of cortisol?
Amino acids and Glycerol
How does cortisol impact the immune system?
Cortisol stabilizes lysosomal membranes and decreases the release of proteolytic enzymes by damaged cells
What is the effect of cortisol on the reproductive system?
Cortisol inhibits various mechanisms of action, causing a decline in reproductive success
How does cortisol impact the cardiovascular system?
Cortisol increases vascular smooth muscle sensitivity to vasoconstrictors and helps maintain blood pressure
What is the impact of cortisol on growth?
Cortisol inhibits various mechanisms of action, causing inhibition of insulin-like growth factors (IGF-1)
What is the significance of the zona reticularis in the adrenal gland?
The zona reticularis produces androgens, which are not significant in most animals
Which receptor is responsible for vasoconstriction and increased peripheral resistance?
Alpha 1 receptor
Which of the following is a direct effect of catecholamines binding to beta 1 receptors?
Increased lipolysis
Catecholamines binding to which receptor is responsible for thermogenesis and lipolysis within adipose tissue?
Beta 3 receptor
Which effect of catecholamines is mediated through the stimulation of alpha 1 receptors?
Mydriasis (eye dilation)
Which of the following is a direct effect of catecholamines binding to beta 2 receptors?
Increased muscle and liver glycogenolysis
Which receptor is responsible for bronchodilation caused by catecholamines?
Beta 2 receptor
Which of the following effects of catecholamines is mediated through the stimulation of beta 1 receptors?
Tachycardia
Which effect of catecholamines is responsible for the increase in available glucose during acute stress?
All of the above
Which hormone is responsible for increasing libido and secondary sexual characteristics in humans?
Androgens
In the catecholamine synthesis pathway, what happens right after the conversion of L-DOPA to dopamine within the cytosol of the chromaffin cell?
Dopamine is converted to norepinephrine, within a chromaffin granule
What is the main function of norepinephrine (NE) in the catecholamine metabolism pathway?
Exerts negative feedback on pre-ganglionic sympathetic receptors
What is the first step in the metabolism of epinephrine (EPI) via the COMT pathway within catecholamine metabolism?
EPI uses COMT to convert into metanephrine
Which precursor molecule is converted into androstenedione in the androgen production pathway?
Dehydroepiandrosterone (DHEA)
What is the half-life of epinephrine (EPI) in the catecholamine metabolism pathway?
2 minutes
In the catecholamine synthesis pathway, what happens right after the conversion of dopamine into norepinephrine (NE)?
Norepinephrine goes to the cytosol and is converted into epinephrine
What is the primary function of catecholamines in the flight or fight response?
Increase energy availability and overall metabolism
Which of the following is NOT a function of cortisol in regulating gene expression?
Photosynthesis regulation
What is the primary role of cortisol in fat metabolism?
Shifting metabolism from glucose to fat
What is the primary source of amino acids for gluconeogenesis during cortisol-stimulated protein catabolism?
Skeletal muscle
What happens to free fatty acids (FFA) when cortisol levels are elevated?
FFA are transported from adipose tissue to the liver and abdomen
Which of the following is NOT a potential consequence of long-term excessive cortisol release?
Increased protein synthesis
What is the primary effect of cortisol on carbohydrate metabolism?
Increasing blood glucose levels
Which of the following is a factor that stimulates glucocorticoid production in the adrenal gland?
All of the above
What is the consequence of the surplus of free fatty acids (FFA) being redirected to the liver and abdomen?
Increased visceral (abdominal) fat and a pot belly appearance
Which statement accurately describes the effect of cortisol on glucose transport into fat cells?
Cortisol inhibits glucose transport into fat cells
What is the primary function of the hypothalamus in the HPA-axis?
Produce CRH
Which of the following statements about the diurnal rhythm of cortisol production is correct?
Cortisol production is higher in the morning than at night.
Which of the following is NOT a symptom associated with elevated cortisol levels, according to the text?
Increased peripheral fat deposits
High cortisol levels can lead to what illness that is also known as "Steroid Diabetes"?
Diabetes Mellitus
What is the primary source of energy for muscles when cortisol levels are elevated?
Free fatty acids (FFA)
What is the first step in the metabolism of norepinephrine (NE) via the MAO pathway within catecholamine metabolism?
NE uses MAO to convert into dihydroxymandelic acid
Study Notes
Catecholamines and Stress Response
- Catecholamines bind to adrenoceptors, including alpha 1, alpha 2, beta 1, and beta 2 receptors
- This binding stimulates various effects, including:
- Increased heart rate and force of contractions, resulting in increased blood pressure
- Vasoconstriction of visceral organs, causing restricted blood flow
- Vasodilation of skeletal muscle and liver arterioles, increasing glycogenolysis and glucose availability
- Lipolysis in adipose tissue, increasing ATP production from FFA and glycerol
- Increased basal metabolic rate
Catecholamine Binding to Adrenoceptors
- Alpha 1 receptors:
- Vasoconstriction
- Increased peripheral resistance
- Mydriasis (eye dilation)
- Mucosa decongestion
- Hyperglycemia
- Contraction of pilomotor muscles
- Beta 1 receptors:
- Tachycardia
- Increased lipolysis
- Increased myocardial contractility
- Increased renin release
- Beta 2 receptors:
- Vasodilation
- Increased peripheral resistance
- Bronchodilation
- Increased muscle and liver glycogenolysis
- Increased glucagon release
- Beta 3 receptors:
- Thermogenesis and lipolysis in adipose tissue
HPA-Axis and Cortisol Production
- The HPA-axis consists of the hypothalamus, pituitary, and adrenal glands
- Cortisol production is stimulated by stressors such as low blood glucose, hypovolemia, and emotional stress
- Cortisol increases expression of genes regulating metabolism, cardiovascular system, reproduction, growth, immune system, and circadian rhythm
Cortisol Effects
- Increases protein catabolism, mobilizing amino acids from extrahepatic tissue
- Reduces cellular protein synthesis of body proteins
- Long-term excessive cortisol release can lead to muscle wastage, osteoporosis, and other effects
Catecholamine Synthesis and Metabolism
- Catecholamine synthesis occurs in the adrenal medulla, involving L-tyrosine, L-DOPA, dopamine, norepinephrine, and epinephrine
- Catecholamine metabolism involves COMT and MAO systems in the liver and kidneys, resulting in VMA excretion in urine
Cortisol Impact on Lipid Metabolism
- Increases mobilization of fatty acids from adipose tissue
- Increases libido and secondary sexual characteristics in humans
Cortisol Impact on Diabetes Mellitus
- High cortisol levels can lead to diabetes mellitus due to increased gluconeogenesis and decreased glucose usage
- 10% of dogs with hyperadrenocorticism (Cushing's disease) will also develop diabetes mellitus
- Prolonged administration of glucocorticoids can also cause diabetes mellitus
Test your knowledge on zona fasciculata, glucocorticoid production, and the HPA-axis. Learn about the factors that stimulate glucocorticoid production and its effects on gene regulation in various body systems.
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