Adrenal Gland Flashcards
Layers of adrenal glands (2)
Adrenal cortex
Adrenal medula
Adrenal cortex
Mesodermal in origin
Organized in 3 zones
Adrenal medulla
Ectodermal in origin
What produces the steroid hormones
Adrenal cortex
Steroids are derived from
Cholesterol
Adrenal cortex characteristics for steroid synthesis (3)
Abundance of lipid droplets containing cholesterol esters
Mitochondrion
Smooth ER
Production of adrenal steroids involved the classic pathway for steroids biosynthesis.
The first step is
Cholesterol is used to form pregnenolome
Formation of pregnenolome occurs where
In mitochondrion
Formation of pregnenolome is regulated by
ACTH
Mechanisms of actions of ACTH Adrenocortical steroidogenesis (4)
Stimulation of the uptake of LDL
Stimulation of the hydrolysis of stored cholesterol ester to generate free cholesterol
Stimulation of the transport of cholesterol into the mitochondria, where cleavage of cholesterol side chains occurs
Promotion of the binding of cholesterol to the enzyme
Adrenal cortex hormones bind to
Steroid hormones bind to IC receptor
Receptors are located in the cytosol or nucleus
Metabolism of adrenal cortex involves
The liver
The liver does what
Modifies hormones for excretion
Zona glomerulosa
Outermost zone and produces mineralocorticoids
Aldosterone is produced or released where
Zona glomerulosa
Aldosterone role
Plays important role in electrolyte balance and regulation of blood pressure
Aldosterone actions are carried out at
Level of distal tubules in the kidneys
Why is aldosterone important
Important to keep or maintain blood volume retaining salt
Production of aldosterone is regulated by
RAAS
RENIN ANGIOTENSIN ALDOSTERONE SYSTEM
The stimuli for aldosterone secretion is made by
Decrease volume plasma sodium concentration
What is another major regulatory factor for mineralocorticoid secretion
Potassium
What is the zona fasciculata
Middle zone
Zona fasciculata produce
Glucocorticoids
What is the major glucocorticoid
Cortisol
Cortisol is considered
A stress hormone
What stimulates the secretion of cortisol
ACTH produced from adenohypophysis
ACTH =
Corticotrophin
Secretion of corticotrophin is controlled by
Corticotrophin releasing factor (CRF) from hypothalamus
What influences the axis
Glucocorticoids, stress and diurnal rhythm
Cortisol effects occur after what
Binding to the nuclear receptors located into the cytosol
Cortisol in carbohydrate metabolism does what (6)
Stimulates synthesis of enzymes involved in gluconeogenesis
Causes mobilization of a.a from extra hepatic tissues
Antagonizes insulins effects
Decrease glucose utilization, and GLUT 4 translocation
Potentiates the action of glucagon and epinephrine on glucose metabolism
Cause diabetes mellitus
What are the main substrates used in the synthesis of enzymes involved in gluconeogenesis during stress
A.a derived from muscle
T or F
Decrease GLUT 4 translocation in skeletal muscle leads to insulin resistance
True
Diabetes Mellitus (2)
Increase gluconeogenesis and reduction in glucose utilization
About 20% of dogs with HAC develop DM
Cortisol in protein metabolism (2)
Reduces cellular protein
Increases liver and plasma proteins
Cortisol on fat metabolism (2(
Increase mobilization of fatty acids from adipose tissue
Can cause obesity
Increase mobilization of fatty acids from adipose tissue causes what (2)
Enhance the oxidation of FFAs in cells
Shift the metabolism from glucose to fat utilization
T or F
Cortisol can cause obesity
True
It can deposit fat into places
T or F
Cortisol acts as a immunosuppresor and anti-inflammatory
True
What is the zona reticularis
Innermost zone
What does the zona reticularis produce
Androgens
What are androgens
Hormones that interact with male sex hormone receptors
T or F
Dehydroepiandrosterone and androsterone are highly active
False
Not as active as testosterone
What can happen to androgens in the adipose tissue
Can be converted into testosterone or estrogens
What regulates the production of androgens
ACTH
T or F
Adrenal androgen is very important in animals
False
What is the adrenal medula
Apostsynaptic ganglia of the sympathetic nervous system
Adrenal medula secretes what
Neurotransmitters into blood
What is the primary catecholamine produces in adrenal medula
Epinephrine
What initiates the synthesis in adrenal medulla
Begin with the conversion of tyrosine to DOPA by tyrosine hydroxylase
What produces epinephrine in adrenal medula
Chromafin cells from the a.a. tyrosine
End product of tyrosine metabolism include (4)
DOPA
Dopamine
Epinephrine
Norepinephrine
Where is DOPA converted into dopamine
In the cytosol
Catecholamine’s action involve what
Involve the regulation of intermediary metabolism and responses that allow animals to adjust to situations involving acute stress
What are the major types of catecholamine
Alpha
Beta
Stimulation of alpha receptors in the anterioles of most visceral organs causes what
Contraction of arteriolar smooth muscle
Increase blood pressure, restrict blood flow
Catecholamine can (5)
Cause vasodilation of skeletal muscle and liver anterioles
Increase heart rate and force contraction of each heartbeat
Increase breakdown of glycogen in liver and muscle
Stimulate lipolysis in adipose tissue
Increase basal metabolic rate
