Arroyo: Adrenals & Pituitary

Question 1

Adrenal gland location

Answer 1

Superior border of each kidney

Question 2

What layers can the adrenal gland be subdivided into?

Answer 2

Cortex (superficial) Medulla (inner)

Question 3

What does the adrenal cortex do? What hormone(s) does it secrete?

Answer 3

• Cortex (superficial)
  
  • Stores lipids (esp. cholesterol and FAs)
  • Makes steroid hormones (corticosteroids)
    
    • Aldosterone - water retention
    • Cortisol - helps you deal with stress

Question 4

What does the adrenal medulla do? What hormone(s) does it secrete?

Answer 4

• Medulla (inner)
  
  • Secretory activity controlled by sympathetic NS
  • Makes Epi and NE - enhance fight or flight
  • Metabolic changes persist for several minutes

Question 5

What are the different layers of the adrenal cortex?

Answer 5

• Zona glomerulosa (outer)
• Zona fasciculata (middle)
• Zona reticularis (innermost)

Question 6

Zona glomerulosa - what hormone(s) does it secrete? What do those hormone(s) do?

Answer 6

• Zona glomerulosa (outermost)
  
  • Produces mineralocorticoids i.e. aldosterone
    
    • Aldosterone
      
      • Stimulates conservation of Na+ ions and elimination of K+ ions
      • ↑sensitivity of salt receptors in taste buds
      • Secretion responds to
        
        • ↓blood Na+, BV, BP
        • ↑blood K+ concentration

Question 7

Zona fasciculata - what hormone(s) does it secrete? What do those hormone(s) do?

Answer 7

• Zona fasciculata (middle)
  
  • Produces glucocorticoids i.e. cortisol with corticosterone
    
    • Liver converts cortisol to cortisone
    • Glucocorticoids accelerate glucose synthesis and glycogen formation
• Show anti-inflammatory effects
  
  • Inhibit activities of WBCs and other components of immune system
  • Side effect of increased susceptibility to infection
• Used to tx:
  
  • Rheumatoid arthritis
  • Lupus
  • Inflammatory bowel disease
• Long-term use is contraindicated
  
  • Cushing’s disease-like effects
• Secretion regulated by NEGATIVE FEEDBACK
• Inhibitory effect on production of
  
  • Corticotropin-releasing hormone (CRH) in hypothalamus
  • ACTH in adenohypophysis

Question 8

Zona reticularis - what hormone(s) does it secrete? What do those hormone(s) do?

Answer 8

• Zona reticularis (innermost)
  
  • Network of endocrine cells
  • Forms narrow band bordering each adrenal medulla
  • Produces androgens under stimulation by ACTH

Question 9

Adrenal Cortex Disorders: Hypersecretion and Hyposecretion

Answer 9

• Cushing’s Syndrome
  
  • Hypersecretion of glucocorticoids (cortisol)
  • Signs/Symptoms: Re-distributed body obesity, “moon face,” “buffalo hump,” kidney stones, skin becomes fragile and thin
• Addison Disease
  
  • Hyposecretion of glucocorticoids and sometimes mineralocorticoids (aldosterone)
  • Symptoms: Weight loss, general fatigue, hypotension, skin darkening

Question 10

What tissues do Epi and NE target?

Answer 10

• Skeletal muscle
• Adipose
• Liver
• Heart

Question 11

What are the effects of adrenal medulla activation?

Answer 11

Epi & NE

• Skeletal muscles
  
  • Trigger mobilization of glycogen reserves
  • Accelerate glucose breakdown to provide ATP
  • This combination increases muscular strength and endurance
• Adipose tissue
  
  • Stored fats are broken down into FAs, which are released into the bloodstream for other tissues to use for ATP production
• Liver
  
  • Glycogen molecules are broken down
    
    • Resulting glucose molecules are released into the bloodstream
    • Primarily for use by neural tissue, which cannot shift into FA metabolism
• Heart
  
  • Stimulation of beta 1 receptors trigger an ↑in rate and force of cardiac muscle contraction

Question 12

Pancreas location

Answer 12

Lies between inferior border of stomach and proximal portion of small intestine

Question 13

What type of cells comprise the pancreas? What are the names of these cells?

Answer 13

• Exocrine
  
  • Pancreatic acini
• Endocrine
  
  • Pancreatic islets or islets of Langerhans

Question 14

Exocrine vs. Endocrine pancreatic cells? What hormone(s) are secreted by each?

Answer 14

• Exocrine
  
  • Pancreatic acini: clusters of exocrine gland cells
  • Takes up ~99% pancreatic volume
    
    • Gland and duct cells secrete alkaline, enzyme-rich fluid
    • Reaches lumen of digestive tract through a network of secretory ducts
• Endocrine
  
  • Pancreatic islets or islets of Langerhans: clusters of endocrine gland cells
    
    • Alpha cells produce glucagon
    • Beta cells produce insulin
    • Delta cells produce peptide hormone identical to GH-IH
    • F cells secrete pancreatic polypeptide (PP)

Question 15

Pancreas - Which cells release which hormones when blood glucose levels fluctuate?

Answer 15

Blood Glucose Levels

• When levels rise
  
  • Beta cells secrete insulin, stimulating glucose transport across plasma membranes
• When levels decline
  
  • Alpha cells secrete glucagon, stimulating glucose release by liver

Question 16

What does insulin do?

Answer 16

Insulin - released beta cells

• Affects target cells
  
  • Accelerates glucose uptake
  • Accelerates glucose utilization and enhances ATP production
  • Stimulates glycogen formation
  • Stimulates amino acid absorption and protein synthesis
  • Stimulates triglyceride formation in adipose tissue
  • Inhibits adipocyte lipolysis

Question 17

What does glucagon do?

Answer 17

Glucagon - released by alpha cells; mobilizes energy reserves

• Affects target cells
  
  • Stimulates glycogen breakdown in skeletal muscle and liver cells
  • Stimulates breakdown of triglycerides in adipose tissue
  • Stimulates production of glucose in liver (gluconeogenesis)

Question 18

Diabetes Mellitus

Answer 18

• Characterized by glucose concentrations high enough to overwhelm the reabsorption capabilities of the kidneys
  
  • Hyperglycemia = abnormally high glucose levels in the blood
  • Glucose is in the urine, and urine volume generally becomes excessive (polyuria)
• Most common non-communicable disease
• High morbidity and mortality
• Leading cause of blindness and kidney disease

Question 19

What are complications of untreated or poorly managed diabetes mellitus?

Answer 19

• Kidney degeneration
  
  • Diabetic neuropathy - degenerative changes in kidneys, leading to kidney failure
• Retinal damage
  
  • Diabetic retinopathy - proliferation of capillaries and hemorrhaging at the retina = partial or complete blindness
• Early heart attacks
  
  • May be caused by degenerative blockages in cardiac circulation
• Peripheral nerve problems
  
  • Abnormal blood flow to neural tissues is probably responsible for a variety of neural problems with peripheral nerves, including abnormal autonomic function
    
    • AKA Diabetic Neuropathy
• Peripheral nerve damage
  
  • ↓blood flow to distal portions of limbs, peripheral tissues may suffer as a result
    
    • Can lead to tissue death, ulceration, infection, loss of toes or major portion of one or both feet

Question 20

Type 1 Diabetes

Answer 20

Type 1 Diabetes (Insulin-_Dependent_ Diabetes Mellitus - IDDM)

• Characterized by inadequate insulin production by pancreatic beta cells
• Persons with T1DM require multiple insulin injections per day to live
• Often develops around childhood

Question 21

Type 2 Diabetes

Answer 21

Type 2 Diabetes (Insulin Independent Diabetes Mellitus - IIDM)

• Most common form of diabetes mellitus
• Most people with this form of diabetes produce normal amounts of insulin (at least initially) but they are insulin resistant
• T2DM associated with obesity - weight loss via diet and exercise is effective tx
• Age is most common cause - Arroyo

Question 22

What hormones are important for growth?

Answer 22

• Growth hormone (GH)
  
  • Children - supports muscular and skeletal development
  • Adults - maintains normal blood glucose concentrations; mobilizes lipid reserves
• Thyroid hormones
  
  • If absent during fetal development or 1st year
    
    • Nervous system fails to develop normally = mental retardation
  • If TH concentrations decline before puberty
    
    • Normal skeletal development will not continue
• Insulin
  
  • Allows passage of glucose and amino acids across plasma membranes
• PTH and calcitriol
  
  • Promotes absorption of Ca2+ salts for deposition in bone
  • Inadequate levels cause weak and flexible bones
• Reproductive hormones
  
  • Androgen in male; estrogen in female
  • Stimulate cell growth and differentiation in target tissues
  • Gender-related differences in
    
    • Skeletal proportions
    • Secondary sex characteristics

Question 23

What is the hormonal response to stress called? What are the various phases called?

Answer 23

• General Adaptation Syndrome (GAS)
  
  • AKA stress response - how body responds to stress-causing factors
  • Three phases
    
    • Alarm - fight or flight; immediate short-term response to crises
    • Resistance - long-term metabolic adjustment
    • Exhaustion - collapse of vital systems

Question 24

What effects can hormones have on behavior?

Answer 24

• Alter intellectual capabilities, memory, learning, emotional status
• Affect behavior when endocrine glands are over-/under-secreting

Question 25

What homonal changes may occur during aging?

Answer 25

* Few functional changes * ↓concentration of **growth hormone** and **reproductive** **hormones**