! BIOL 1410 Endocrine system

LECTURE 18

What 2 things are contained within the endocrine system?

Ductless glands + endocrine tissues

What does the endocrine system secrete into blood?

Hormones

What is a target cell?

Cell with receptor specific for a hormone

What are the 3 hormone classes?

Steroids, hormones derived from amino acids, peptide/protein hormones

What are steroids synthesized from?

Cholesterol

What are 3 examples of steroid hormones?

Testosterone, estrogen, vitamin D

Tyrosine, an amino acid, has hormones that derive from it (2nd hormone class). What 3 hormones are derived from it?

Thyroxine/T₄, epinephrine (adrenaline), norepineprine (noradrenaline)

What is thyroxine/T₄ (+ what it controls)?

A thyroid hormone that controls metabolism, growth and development

What are epinephrine (adrenaline) + norepinephrine (noradrenaline) secreted by?

Adrenal medulla

Peptide + protein hormones are chains of amino acids. What type of bonds hold amino acids together?

Peptide bonds

Peptide hormone is _____ chains of linked amino acids, while protein hormone is _____ chains of linked amino acids

“short,” “long”

What are 4 examples of peptide + protein hormones?

Oxytocin, antidiuretic hormone (ADH), growth hormone (GH), insulin

What are the 4 glands with no other function?

Pituitary gland, thyroid gland, parathyroid glands, adrenal glands

Where is the pituitary gland found?

Suspended from hypothalamus in sella turcica of sphenoid bone

What are the 2 lobes of the pituitary gland?

Anterior pituitary, posterior pituitary

What is the anterior pituitary hormone secretion regulated by?

Hormones released by the hypothalamus

What are the 5 hormones the anterior pituitary secretes?

Growth hormone (GH), thyroid stimulating hormone (TSH), adrenocorticotropic hormone (ACTH), luteinizing hormone (LH), follicle stimulating hormone (FSH)

What reproductive hormone does the anterior pituitary secrete?

Prolactin (PRL)

What 2 things does the growth hormone (GH) affect?

Growth + metabolism

What does the thyroid stimulating hormone (TSH) do?

Stimulates secretion of thyroid

What does the adrenocorticotropic hormone (ACTH) do?

Stimulates secretion of steroids from adrenal gland

What 3 things does the luteinizing hormone (LH) do?

Stimulates ovulation, formation of corpus luteum in ovary, and testosterone production

The luteinizing hormone (LH) stimulates testosterone production by?

Interstitial endocrine (Leydig) cells in testes

What does the follicle stimulating hormone (FSH) do?

Stimulates sustentocytes + follicle cells

What does prolactin/PRL (the reproductive hormone of the anterior pituitary) do?

Stimulates milk production by mammary glands

What type of tissue is the posterior pituitary made of?

Nervous tissue

What is the posterior pituitary an extension of?

The hypothalamus

What 2 hormones are produced in the hypothalamus, but stored + secreted from the posterior pituitary?

Oxytocin, antidiuretic hormone (ADH)

What 2 things does oxytocin do?

Stimulates uterine contractions + milk ejection

What does the antidiuretic hormone (ADH) do?

Enhances water reabsorption by collecting duct in kidney(s)

Where is the thyroid gland found?

On the anterior surface of the superior portion of the trachea (inferior to larynx)

What do people say the thyroid gland is shaped like?

Butterfly shaped

What are the 2 components of the histology of the thyroid gland?

Follicles, parafollicular cells

What do follicles of the thyroid gland produce?

T4

What does T4 turn to in target cells?

Active T3

Where are parafollicular cells found?

Between follicles

What do parafollicular cells secrete?

Calcitonin

What are the effects of calcitonin in the body?

⬆Ca⁺ uptake into bone (bone formation), which lowers blood Ca⁺

How many parathyroid glands are there typically + where?

4 glands embedded in posterior thyroid

What do parathyroid glands secrete?

Parathyroid hormone (PTH)

The parathyroid hormone (PTH) acts on bone and kidneys for what purpose?

To increase blood Ca⁺ levels

Where are adrenal glands found?

On the superior surface of each kidney

What are the 2 parts of adrenal glands?

Adrenal cortex (outer), adrenal medulla (inner)

What tissue type is the adrenal cortex made of?

Epithelial tissue

What does the adrenal cortex secrete?

Steroids only

What are the 3 layers of the adrenal cortex (each layer secretes a different hormone)?

Zona Glomerulosa, Zona Fasciculata, Zona reticularis

What does Zona Glomerulosa secrete (+ function)?

Mainly aldosterone; salt balance

What does Zona Fasciculata secrete (+ function)?

Mainly cortisol; long-term stress hormone

What does Zona reticularis secrete (+ function)?

Androgens (sex hormones)

What are androgens converted to in other tissues?

Testosterone or estrogens

The adrenal medulla is modified _______ tissue

“nervous”

What are the 2 main hormones of the adrenal medulla?

Epinephrine (80%), norepinephrine (20%)

What are the ~4 hormone secreting cells/tissues in organs that have other functions as well?

Pancreatic Islets of Langerhans, hypothalamus, gonads, others...

What 2 cells are included in pancreatic islets of langerhans?

α-cells, β-cells

What do α-cells secrete (+ function)?

Glucagon; ⬆blood glucose

What do β-cells secrete (+ function)?

Insulin; ⬇blood glucose

The hypothalamus regulates the anterior pituitary via what 3 hormones?

GHRH (GH releasing hormone), GHIH (GH inhibiting hormone), GnRH (Gonadotropin releasing hormone)

GnRH (Gonadotropin releasing hormone) stimulates the release of what 2 hormones?

FSH (Follicle-Stimulating Hormone) + LH (Luteinizing Hormone)

The hypothalamus produces hormones stored + secreted by the ________ pituitary

“posterior”

In testes (male gonads), what type of cells secrete what type of hormone?

Interstitial endocrine (Leydig) cells; testosterone

In ovaries (female gonads), what 2 types of cells secrete what types of hormones?

Granulosa cells of 2° and vesicular follicles; estrogen

Corpus luteum; estrogen + progesterone

What hormone secreting cells/tissues in organs with other functions are included in the “others” category?

Duodenum, kidney, skin, heart, etc.

What 2 hormones does the duodenum secrete?

Secretin + cholecystokinin (CCK)

What 2 hormones does the kidney secrete?

Renin + erythropoietin (EPO

What hormone is secreted by the skin?

Vitamin D

What hormone is released by the heart?

Atrial Natriuretic Peptide (ANP)