Adrenal Glands Flashcards
Adrenal gland location
-anatomical direction
-adhered to what blood vessels on left and right
-symmetrical or asymmetrical?
• Paired glands lie against the roof of the abdomen near the thoracolumbar junction.
• Retroperitoneal craniomedial to the corresponding kidney.
• Adhered to Aorta on left and caudal vena cava on right
• Asymmetrical in shape and location
Outflow of blood in adrenal glands travels into…
Caudal vena ceva
Two anatomically and functionally distinct layers
outer cortex, can be yellowish in colour, radially striated
inner medulla darker more uniform
Adrenal gland structures are held toegether/ all surrounded by…
dense fibrous capsule (yellowish)
Adrenal gland blood supply
-arteries supplying blood form…
• Supplied by the superior, middle and inferior suprarenal arteries which form a plexus beneath capsule
Describe the structure of the arteriole and arteries within adrenal gland receiving the blood
• Cortical arteries and arterioles branch into capillary beds within the cortex (supplied by branches of the subcapsular plexus) (short cortical arteries).
They pass through the Fasciculata into a deep plexus in reticularis before draining into venules that converge upon the central medullary vein.
• Long cortical arteries run through cortex; descend to medulla before branching to form capillary beds in the medulla which drain into the central medullary vein
• central medullary vein, anastomoses with either the vena cava or renal vein
How many capillary beds found within adrenal gland?
2
Adrenal cortex
-______________ origin derived from ____________ epithelium close to gonadal ridge.
-made of 3 layers
Mesodermal origin derived from celomic epithelium close to gonadal ridge.
- Zona glomerulosa
- Zona fasciculata
- Zona reticularis
The three layers of cortex contain abundance of…
abundance of lipid droplets, mitochondria and smooth ER.
Adrenal medulla
-what kind of origin?
Neuroectodermal origin
What does the adrenal cortex produce?
What does the adrenal medulla produce?
-3 steroid hormones (lipid soluble)
-catecholamines (water soluble)
What hormone does the Zona Glomerulosa of adrenal cortex produce?
What is their function?
Mineralocorticoids (mostly aldosterone)
-Stimulates the reabsorption of Na+ from urine, saliva, gastric juices and sweat
ESSENTIAL for life
What hormone does the Zona Fasciculata of adrenal cortex produce?
What is their function?
glucocorticoids (cortisol/corticosterone)
regulation of glucose metabolism
Metabolic homeostasis
Adaptation to stress
Anti-inflammatory
What hormone does the Zona Reticularis of adrenal cortex produce?
What is their function?
Androgens (small amount of glucocorticoids)
Precursors of sex steroids
Sexual differentiation
Protein anabolism
What are some things that can happen if there’s something wrong with production of mineralocorticoids hormone?
Hypertension
Cellular hypertrophy
Remodelling and fibrosis
Oxidative processes
Decreased insulin sensitivity
^ adipogenesis
What are some things that can happen if there’s something wrong with production of glucocorticoids hormone?
Visceral obesity
^ free fatty acid
Triglycerides accumulation
Metabolic syndrome
What are some things that can happen if there’s something wrong with production of androgens hormone?
Polycystic ovary syndrome
Hyperinsulemia
Insulin resistance
How are the steroid hormone within cortex produced?
Cholesterol gets taken up which changes into prognenolone which produces these enzymes
Cortex - Zona Glomerulosa histological features
-wide diameter capillaries
-columnar shaped cells
-arranged in irregular cords
-prominent nuclei, less cytoplasm than fasciculata
-lots of ER and mitochondria
-lipid droplets
Aldosterone levels are regulated by what system?
renin-angiotensin system
Quick effects of aldosterone
Long term effects of aldosterone
Quick- altering ability of Na+K+ channel and Na+K+ATPase activity
Long term- changes in number of Na+ K+ channels
Hyperaldosteronism (conn’s syndrome)
-2 TYPES OF CAUSES
-occur at what age/animal
Primary cause—> adrenal gland overproduces aldosterone as its not being regulated properly due to low renin levels causing adrenal tumour (usually affects only one gland)
Secondary—> overstimulation of adrenal gland causing bilateral adrenal hyperplasia (usually both glands affected)
Older cats, sometimes dogs
Symptoms associated with hyperaldosteronism
- Disturbances in salt levels;
Hypokalemia (↑ K+ excretion)
Hypernatremia (↑ plasma Na+)
Metabolic alkalosis - Lethargy
- Hypertension
Blindness
Renal failure
Muscle weakness
Cervical ventroflexion (cats)
Cortex - Zona Fasciculata histological features
• Largest zones in the cortex.
• Cells are polyhedral and usually have a foamy appearance (lipid droplets).
• Poorly stained cytoplasm, rich in ER, mitochondria.
• Cells arranged in distinctively straight cords that radiate toward the medulla.
• Prominentcorticalcapillaries
Describe how the body produces ^ cortisol, corticosterone in the Zona fasciculata of cortex
High brain centres impose a circadian rhythm causing ^ stress—>
This feeds down to hypothalamus where corticotrophin releasing hormone is released—>
Releasing hormone acts at level of pituitary gland (anterior pituitary gland)—>
At level of anterior pituitary gland adrenocorticotrophic Hormone (ACTH) is released->
ACTH passes into circulation till it reaches adrenal gland and causes releasing of cortisol, corticosterone
Stimulating stress axis i.e ^ cortisol, corticosterone levels increases what processes?
- AA releases from skeletal muscle
- AA uptake by the liver
- Hepatic gluconeogenesis
- Carbohydrate synthesis and storage
- Lipolysis and FA release
- Water excretion
- Gastric acid secretion
Stimulating stress axis i.e ^ cortisol, corticosterone levels decreases what processes?
(Decreases all processes counteracting the increase in energy its causing to coupe with stress going on)
- Insulin secretion (maximise amount of free glucose)
- DNA synthesis
- Minimising immune response
- Carbohydrate utilisation
- Inflammation
- Inhibits of ACTH
Hyperadrenocorticism (Cushing’s syndrome)
-what is it
-3 forms
Overproduction of cortisol
- Adrenal tumours, secrete cortisol independently of ACTH (more common in females than males)
- Pituitary hyperplasia, non-pituitary ACTH- or CRH-secreting tumours
- Pituitary tumour, excess production of ACTH (85% of cushings dogs)
Symptoms associated with Cushing’s syndrome
Polyuria, polydipsia, Polyphagia Lethargy
Panting (dogs)
Recurrent UTIs
Loss of muscle mass
Hair loss, (symmetrical, dogs)
Long hair, delayed shedding (horses)
Adrenocortical insufficiency (Addison’s disease).
-what is it
-2 forms (which is most common)
Insufficient Cortisol AND aldosterone secretion
- Primary – defect at the adrenal gland, most common, autoimmune (body starts to destroy its own tissue)
- Secondary – pituitary tumour, or following discontinuation of long-term
steroid treatment
What is Iatrogenic Cushing’s syndrome
Animal has been treated for a long time so drug begins to mimicking effect of cortisol
Symptoms associated with Addison’s disease
Lethargy and weakness
Poor appetite
Vomiting, diarrhoea, weight loss
Depression
Dehydration Polydipsia polyuria
Low plasma glucose
Weak pulse, slow heart rate (K+ retention)\
Shaking
Low body temp
^ pigmentation
Cortex - Zona Reticularis histological features
Regulated by…
Size varies due to…
• Innermost zone of the cortex
• Cells arranged in cords projecting in many different directions that anastomose with one another.
• Cells are smaller, with strongly staining cytoplasm and no lipid droplets
• Capillaries between cords.
Regulated by hypothalamus via pituitary
Different physiological conditions
Main regulatory factor in Regulation of androgen secretion
ACTH
Medulla histological features
-venous channels drain blood from…
-shape of secretory cells & chromaffin cells
Closely packed clusters of secretory cells supported by fine collagen containing wide diameter capillaries.
• Venous channels drain blood from sinusoids of the cortex pass through
• Secretory cells, chromaffin cell are columnar, have large nuclei, strongly basophilic faintly granular cytoplasm (few ER, no lipids)
Medulla of adrenal gland is richly innervated by…
What other cells are commonly seen in medulla
Sympathetic fibres
Ganglion cells
Ganglion cells shape and nuclei
round or polygonal with prominent nuclei
Main hormone produced in medulla
Catecholamines;
Adrenaline/epinephrine, noradrenaline/norepinephrine, dopamine
True or false Secretion of Adrenaline > noradrenaline in medulla
True
