Hormones of the Endocrine System

What class of hormones is cortisol in

glucocorticoid class

Source of Cortisol

Produced and secreted by the cells in the zona fasciculata in adrenal glands

Cortisol stimulus

stressful stimuli/ low blood pressure

Cortisol stimulus: Hypothalamus releases what to the anterior pituitary

Corticotropin releasing hormone (CRH)

Cortisol Stimulus- In the anterior pituitary CRH binds to

corticotroph cells

Cortisol Stimulus- The anterior pituitary releases

Adrenocorticotropic hormone (ACTH)

Cells in the Zona fasciculata convert what to what

Cholesterol to Cortisol

Is cortisol stored?

No, it is secreted as it is produced, pulsatile and peak in morning

Receptor for cortisol

nearly every cell in the body, intracellular

Cortisol target organs/tissues

Adipose tissue, Liver, Muscle, Blood vessels, Bone, and General tissues

Cortisol function in adipose tissue

triggers lipolysis which breaks down fats for energy

Cortisol function in Liver

triggers gluconeogenesis and increases glycogen storage which increases glucose and glucose stored

Cortisol function in muscle

stimulates proteolysis which generates proteins to amino acids that are available for gluconeogenesis

Cortisol function in blood vessels

Up regulates alpha 1 adrenergic receptors which causes vasoconstriction and increases blood pressure

Cortisol function in Bones

Inhibits osteoblasts, and decreases production of type 1 collagen which is needed for new bone matrix → therefore decrease bone formation

Cortisol function in General tissues

increases insulin resistance which causes insulin to be less effective at moving glucose into cells which increases glucose levels

Cortisol Negative feedback

If Cortisol levels get too high then that will trigger the hypothalamus to stop making CRH and the anterior pituitary gland to stop making ACTH

Insulin’s source

Pancreas- Islets of Langerhans (Beta Cells)

Insulin stimulus

Increased glucose levels, increased blood glucose, cortisom (fatty acids and amino acids), and Acetylcholine (PNS)

Insulin Inhibitors

Norepinephrine, and Somatostatin or growth hormone inhibiting hormone

Insulin target organs/tissues

Liver, Adipose Tissue, Skeletal Muscle, and Adipose cells

Insulin function in liver

puts glucose away as glycogen (stored)

inhibits gluconeogenesis (glucose production)

sends extra glucose to adipose tissue by converting glucose into fatty acids

All this decreases glucose

Insulin function in adipose tissue

fatty acids are converted to fat which increases fat production

Insulin function in skeletal muscle

amino acids are converted to proteins which causes muscle growth

Insulin function in Adipose cells

lipolysis which increases fatty acids into blood stream

Glucagon source

Pancreas- Islets of Langerhans (Alpha cells)

Glucagon stimulus

decreased blood glucose, Adrenaline(SNS) and Cholecystokinin

Target organs/tissue of glucagon

Liver and adipose tissue

Glucagon function on Liver

breakdown of glycogen (stored glucose) to glucose, gluconeogenesis increases glucose, all increase glucose levels (while fasting)

Glucagon inhibitors

High blood glucose, Insulin, Somatostatin and Growth hormone

Glucagon function on Adipose tissue

Lipolysis- fatty acids released in blood

Growth hormone (Somatotropin) Source

Anterior pituitary (hypothalamic-pituitary axis)

What cells in the anterior pituitary release growth hormone

somatotroph cells

Growth hormone stimulus

Growth hormone releasing hormone from hypothalamus and gets triggered by hypoglycemia (low blood sugar), epinephrine, estrogen and testosterone

Target organs/tissues of Growth Hormone

Adipose tissue, Liver, and tissues

Growth hormone function on adipose tissue

lipolysis-breaks down fats into fatty acids to make available for metabolism

Growth hormone function in the liver

Gluconeogenesis- and glycogenolysis (break down of stored glucose) which overall increases blood glucose

Release of IGF-1

Growth hormone triggers liver to release IGF-1, what does it do?

Muscles: amino acid uptake into muscle cells which increases protein production -→ muscle growth!

Also increases osteoblasts and chondrocytes which causes long bone growth

Growth hormone function in tissues

Increases insulin resistance which increases blood glucose

Growth Hormone negative feedback

Liver, Bone and muscle release somatomedins to the anterior pituitary which stops GH secretion

Growth hormone amd somatomedins trigger hypothalamus to release somatostatin which is is a growth hormone inhibiting hormone which blocks the action of GHRH and somatotroph cells

Somatostatin goes to pancreas and stop release of insulin, glucagon, gastrin and vasoactive intestinal peptides

Source of Antidiuretic hormone

paraventricular and supraoptic nuclei in the hypothalamus

ADH stimulus/triggers

Increased blood osmolarity, Decreased blood pressure, and Angiotensin II

What detects low blood pressure that triggers ADH release

baroreceptors

What detects high blood osmolarity that triggers ADH release

osmoreceptors detect loss of water/excess urine so the trigger hypothalamus thirst response and ADH release in bloodstream

Target tissue/organs of the Antidiuretic hormone

Kidney- principal cells of distal convoluted tubules and collecting duct, Smooth muscle cells in arteries

ADH function on kidney (which part too)

Principal cells of distal convoluted tubule and collecting duct, It inserts aquaporin 2 proteins into apical surface of cell which causes water to travel from the kidney tubule to the bloodstream

Decreases blood osmolarity

ADH function on smooth cells in arteries

cause arteries to constrict which increase vascular resistance and increases blood pressure

ADH negative feedback

Increased blood pressure is detected by the baroreceptors which send signals to hypothalamus that STOPS secretion of hormone

Thyroid Hormone (T3 and T4) source

follicular cells on the Thyroid gland

Thyroid stimulus

Anterior PItuitary secretes TSH or thyroid stimulating hormone to the the thyroid gland after being triggered by the Hypothalamus sending Thyroid-releasing hormone (TRH) to the anterior pituitary

Target organs/tissues of Thyroid hormone

Every cell of the body, Cardiovascular system

What does the thyroid do in general to other hormones?

It increases catecholamines, glucagon and growth hormone through proteolysis (muscle break down), Lipolysis, and gluconeogenesis

Thyroid hormone function on Every cell of the body

activates gene transcription in cells nucleus which increases basal metabolic rate

Thyroid hormone function on cardiovascular system

It increases Beta 1 adrenergic receptors which increase heart contractility and heart rate which increase cardiac output

What are the two versions of thyroid hormone (describe them)

T3- Triiodothyronine which is highly active, and T4- which is less active

T3 and T4 bind to

circulating plasma proteins

Thyroid hormone negative feedback

When there is too much T3 and T4 that sends signals to hypothalamus to stop secreting TRH and also sends signals to anterior pituitary to stop secreting TSH

Parathyroid hormone (PTH) source

Cheif cells in the parathyroid glands

Parathyroid hormone stimulus

Low extracellular calcium/ low calcium in bloodstream

Parathyroid hormone inhibitor

elevated/high extracellular calcium

Target organs/tissues of the parathyroid hormone

Bones (Osteoblasts), Kidneys-Proximal convoluted tubule cells, Kidneys- distal convoluted Principal cells , Epithelial cells in breast, and Hypothalamus

Parathyroid hormone function on Bones

Forms osteoclasts that breakdown the bone and release calcium which increases calcium in the bloodstream

Parathyroid hormone two functions on the Kidneys proximal convoluted tubule cells

stores phosphate reabsorption which leaves in the urine and decreases phosphate in the blood

Activates 1-alpha hydroxylase enzyme which coverts inactive vitamin D to active which increases calcium

Parathyroid hormone function on kidneys distal convoluted principal cells

calcium is reabsorbed out of the urine which increases calcium

Parathyroid hormone function on Epithelial cells in the breast

they are stimulated to increase milk production

Parathyroid hormone function on the hypthalamus

Inhibits gonadotropin-releasing hormones like Luteinizing hormone and follicular-stimulating hormone (from anterior pituitary)

This inhibits ovarian follicular development and ovulation which causes no menstrual period while breastfeeding