Biol 224 Lecture 29: Adrenal Glands, Pineal Glands, Pancreas, and other Endocrine Tissues

In class notes from 10/23 but transcribed from notebook to ipad

Adrenal (Suprarenal) gland

Adrenal medulla

Adrenal Cortex

Adrenal Medulla

Neuro-endocrine cells

Secretes epinephrine (~75-80%) and norepinephrine (~20-25%)

Produce increased availability of energy resources

Produce increased rate and force of cardiac contractions and other sympathetic effects

Adrenal Cortex

Gland cells

Secretes steroid hormones (corticosteroids)

How does the adrenal cortex produce increased availability of energy?

• cause breakdown of glycogen in liver to release glucose for use by brain 

• cause breakdown of fat to release fatty acids for use by other cells of body 

What is adrenal medulla controlled by?

Autonomic NS activity

Types of corticosteroids secreted by the adrenal cortex

Mineralocorticoids

Glucocorticoids

Androgens

Mineralocorticoids (aldosterone)

Secreted if sodium is low, potassium is high, or bp is low

cause retention of sodium and water and loss of potassium

Why would aldosterone cause higher bp?

Causes the reabsorption of sodium, water follows where sodium is high, if in blood, larger volume of blood which equates to higher blood pressure

Glucocorticoids (cortisol)

Secreted in response to ACTH release from anterior pituitary and stress

Causes decrease use of glucose and increase rate of glycogen synthesis (mobilizies lipids and fatty acids for energy, conserves glucose for brain) → breaking down adipose tissue for energy saves glucose for brain

have anti-inflammatory effects

Androgens

Encourages bone and muscle growth, blood formation

primary role is in children and women; testes of adult males produces larger amounts

Pineal gland

Secretes melatonin

Increased sunlight exposure causes 

Decreased melatonin secretion 

Possible functions of pineal gland

Setting circadian rhythms

Anti-oxidant

Inhibiting reproductive functions (mostly in other animals, because they’d rather give birth in summer with longer days than winter)

Seasonal Affective Disorder

Depression correlated with decreased sunlight exposure and increase melatonin

Treatment: light therapy

Pancreas

99% of pancreas is exocrine cells (Breaks down everything)

• secretes enzymes into digestive tract

Endocrine cells occur in small clusters

Islets of Langerhans or pancreatic islets

Secrete hormones involved in regulation of glucose levels

Alpha Cells

Secrete glucagon in response to blood glucose levels

Beta cells 

Secrete insulin in response to high blood glucose levels 

Glucose storage

Don’t store much glucose

Tiny amounts in liver stored as glycogen (chain of glucose)

Liver makes glucose from fatty acids

gluconeogenesis is triggered by glycogen → causes us to use fatty acids

Why is insulin called an absorptive hormone?

Insulin lowers blood glucose levels

when we eat we absorb many things, insulin controls where these nutrients/macromolecules go

What is insulin secreted by?

Beta cells

Function of Insulin

Lowers blood glucose levels 

increases rate of glucose uptake and utilization in insulin dependent cells 

• glucose used for energy production and/or synthesis of glycogen and other energy storage macromolecules

increased uptake of fatty acids and synthesis of triglycerides in adipose cells

Increased uptake of amino acids and synthesis of proteins

Glucagon is secreted by what

Alpha cells

Glucagon Function

Raises blood glucose levels

Increase rate of glycogen breakdown

Increase glucose manufactured by liver (gluconeogenesis from amino acids)

Increased release of fatty acids into blood from adipose tissue

• glucose sparing: most cells start using FA as energy source instead of glucose

Glycogen breakdown in liver 

Glucose released into blood

Glycogen breakdown in muscle

Glucose remains in muscle cells

Diabetes

Excess urination

Diabetes insipidus

Polyuria and inadequate ADH secretion

Polyuria 

Excess urine production

Diabetes mellitus

Glucose

Polyuria

Glycosuria

Hyperglycemia

Breakdown of lipids and proteins as energy source for cell metabolism (ketone bodies, ketoacidosis)

Glycosuria

Glucose in urine

Hyperglycermia

Abnormally high glucose levels (normal while fasting is 100 mg, here it’s in couple hundreds)

No insulin receptors or they don’t bind to insulin

Ketone bodies and Ketoacidosis

a life-threatening complication of diabetes that occurs when the body does not have enough insulin to use glucose for energy. As a result, the body breaks down fat for fuel, producing ketones that accumulate in the blood and make it acidic. 

Why does diabetes make you pee more?

Urine is made from plasma, lots of water drawn to glucose, ton of water in kidneys makes you pee more

Types of Diabetes Mellitus

1 and 2

Type 1

Insulin dependent (autoimmune)

• inadequate insulin production

• body destroys beta receptors on pancreas which means it cannot make insulin

Type 2

Non - insulin dependent 

• inadequate insulin receptor response 

Effects of high glucose and or low insulin

Diabetic microvascular disorders and diabetic cardiovascular changes

Endocrine tissue of other systems

Adipose tissue

Intestine

Gonads

Kidneys

Adipose Tissue

Leptin feedback control for appetite (tells us that we have energy and don’t need to eat, but doesn’t work well on humans)

Resistin - reduces insulin sensitivity (Main reason why overweight people have higher risk of diabetes)

Fat secretes hormones

Adipose: energy storage

Intestine

Coordination of digestive activities

Gonads

Ovaries and testes secrete hormones involved in reproductive functions

Kidneys

Hormones regulating blood volume, blood pressure, blood pressure levels

Draw what happens in diabetes