Endocrine System and Homeostasis

Hormones

Hormones – chemical substances that are released into the blood that affect cells, organs and physiological systems of the body

Endocrine System and Homeostasis

Pancreas and control of blood glucose

contains endocrine cells that respond to low blood glucose and produce:

glucagon

• increase breakdown of glycogen to glucose
• increase breakdown of fats to fatty acids
• increase breakdown of proteins to amino acids
• blood glucose rises

contains endocrine cells that respond to high blood glucose and produce:

insulin

• increase rate of glucose transport into cells
• increase rate of glucose utilization
• increases conversion of glucose to glycogen
• increased synthesis
• increased fat synthesis
• blood glucose decreases

Thyroid gland and control of blood calcium

contains endocrine cells that respond to high blood calcium and produce:

calcitonin

• stimulates osteoblasts
• inhibits osteoclasts
• reduces intestinal absorption of calcium
• stimulates calcium ion excretion by kidney
• blood calcium decreases

Parathyroid gland and control of blood calcium

contains endocrine cells that respond to low blood calcium and produce:

parathormone

• inhibits osteoblasts
• stimulates osteoclasts
• increases intestinal absorption of calcium
• inhibits calcium ion excretion by kidney
• blood calcium increases

Thyroid gland and control of metabolism and body temperature

contains endocrine cells that respond to TSH and produce:

thyroxine (T4)

triiodothyronin (T3)

• increase oxygen consumption and energy consumption
• increase heart rate
• produces heat and increases temperature

Adrenal Gland (Medulla) and control of metabolism

contains sympathetic ganglion cells (Chromaffin cells) that produce:

epinephrine and norepinephrine

• stimulates or relaxes smooth muscle
• increase rate of glucose utilization
• increase breakdown of glycogen to glucose
• increase breakdown of lipids to fatty acids
• increase breakdown of proteins to amino acids

Adrenal Gland (Cortex) and control of metabolism

Contains endocrine cells that produce:

aldosterone

• increases renal reabsorption of sodium ions and water
• increases body sodium and water

cortisol

• decreases inflammation and suppresses immune responses
• decreases glucose utilization (glucose sparing)
• increases formation glycogen from glucose
• increases utilization of lipids
• increases breakdown of proteins to amino acids

androgens

• stimulates muscle growth

Anterior Pituitary and control of metabolism

contain endocrine cells that respond to hypothalamic hormones and produce (in part):

Thyroid stimulating hormone (TSH); responds to Thyroid stimulating hormone releasing hormone (TRH)

• stimulates T3 and T4 secretion by thyroid follicles

Adrenocorticotropic hormone (ACTH); responds to Adrenocorticotropic hormone releasing hormone (CRH)

• stimulates cortisol secretion by adrenal gland

Growth hormone (GH); responds to Growth hormone releasing hormone (GH-RH) and Growth hormone inhibiting hormone (GH-IH)

• stimulates bone growth; increases metabolism