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Functions of Endocrine System
Organs that secrete hormones → blood stream
Controls the function of other target organs
A form of long distance communication
Primary Endocrine Organs
Hypothalamus
"head honcho”
Found in brain
Pituitary
“2 parts, anterior and posterior”
Also found in the brain
Pineal
Found in brain
Thyroid and parathyroid
Thymus
Adrenal gland
Pancreas
Testes and ovaries
Structure of Hypothalamus
Neural secretory cells and nuclei that connect to the pituitary gland
Neural secretory cells: neurons that secrete hormones at axon terminal
“Nuclei = anatomical nuclei = several soma, or cell bodies, in the CNS = nucleus
referring to several soma of the secretory cells
Function of Hypothalamus
Controls release of pituitary hormones
Secretes: releasing and inhibiting tropic hormones to the anterior pituitary gland
Tropic hormones: secreted from one gland, causes another gland to secrete another hormone
“Hypothalamus controls the release of hormones in both the posterior pituitary and anterior pituitary. Anterior = uses different tropic hormones and specifically two capillary blood paths”
What are the two hypothalamus connections?
Posterior pituitary
Anterior pituitary
Note for Hypothalamus - Posterior pituitary (PP) connection
*no endocrine (green) cells
Just axons and singular capillary bed
Hypothalamus - Posterior Pituitary (PP) Connection
Neurons in hypothalamus synthesizes (produces) and secretes hormones
Supraoptic nucleus (LHS): oxytocin
Paraventricular nucleus (RHS): Anti-diuretic hormone (ADH)
Hormones stored in terminal vesicles (in PP, at the tip of axon terminals)
When stimulated (by hypothalamus) → vesicles release hormones in capillary beds of PP
*KNOW: Sample of what could be asked about Hypothalamus - PP connection
Produced by _______ nucleus in hypothalamus
Supraoptic nucleus (LHS)
Paraventricular (RHS)
Stored in terminal vesicles of PP
Released from PP even though it’s controlled by hypothalamus
Hypothalamus - Anterior Pituitary (AP) Connection
Portal System
*Uses Tropic hormone to control AP
Stimulated neurosecretory cells release hormones in 1st capillary bed (found in infundibulum)
1st capillary bed → portal vein → 2nd capillary bed (in AP)
Hormones exit capillaries → stimulate AP endocrine cells
AP endocrine cells secrete hormones in (second) capillaries → body for circulation
Parts of the Pituitary Gland
Posterior
Anterior
Structure of Posterior Pituitary Gland
Neural tissue (axon terminals) from hypothalamus
“Neural extension of the hypothalamus”
“Not a true endocrine gland”
Secretions of Posterior Pituitary Gland
Anti-diuretic hormone (ADH) or vasopressin
Targets: kidney
Results: Increased water reabsorption, lower urine volume
*Diuretic = makes you urinate more
*Anti-Diuretic = not make you urinate as much
*ADH = causes you to retain fluids vs. turning into urine = less urine
Oxytocin
Targets: uterus and breasts
Results:
Uterine contraction
Milk expulsion
getting milk out of the breast, different from milk production
Structure of Anterior Pituitary Gland
epithelial tissue
Secretions of Anterior Pituitary Gland
Prolactin
Thyroid stimulating hormone (TSH)
Adrenocorticotropic hormone (ACTH)
Growth hormone (GH)
Luteinizing hormone (LH)
Follicle stimulating hormone (FSH)
*Anterior pituitary gland always controlled by the hypothalamus, so another hormone (tropic) was released from hypothalamus that controlled release of ^
Prolactin
Controlled by hypothalamus:
Prolactin releasing hormone (PRH) (TROPIC)
Prolactin inhibiting hormone (PIH) or dopamine
Acts on: breasts
Result: milk secretion (production), mammary gland development (of breasts)
Thyroid Stimulating Hormone (TSH) (TROPIC)
Controlled by hypothalamus:
Thyrotropin releasing hormone (TRH) (TROPIC)
Acts on: thyroid gland
Results: release thyroid hormones → increased metabolism
Adrenocorticotropic Hormone (ACTH) (TROPIC)
Controlled by hypothalamus:
Corticotropin releasing hormone (CRH) (TROPIC)
Acts on: adrenal gland
Results: releases glucocorticoids (cortisol) → stress responses
Growth Hormone (GH)
Controlled by hypothalamus:
Growth hormone releasing hormone (GHRH) (TROPIC)
Growth hormone inhibiting hormone (GHIH) or somatostatin
Acts on: Liver and cells
Results:
Liver: releases insulin-like growth factors (somatomedins)
*will then act on cells and cause to grow
Cells: signals growth and metabolism
*GH is only tropic if it goes to the liver
Luteinizing Hormone (LH) (TROPIC)
Controlled by hypothalamus:
Gonadotropin releasing hormone (GnRH) (TROPIC)
Acts on: ovaries and testes
Results: ovulation, secretion of sex hormones
Follicle Stimulating Hormone (FSH)
Controlled by hypothalamus:
Gonadotropin releasing hormone (GnRH) (TROPIC)
Acts on: ovaries and testes
Results: development of egg and sperm
Structure of Pineal Gland
Epithelial tissue in brain
What does the pineal gland secrete?
melatonin
Results of secretion from pineal gland:
Regulates circadian rhythm
*helps you sleep
*as it gets darker, pineal gland will secrete melatonin
Structure of Thyroid
Butterfly structure, ventral (front) surface of trachea
Secretions of Thyroid and its Results
Secretes:
Tetraiodothyronine (T4) and Triiodothyronine (T3)
Calcitonin
“tone down the Ca2+”
Results:
Increase metabolism
Lowers Ca2+ levels in blood, deposition in bone
“puts Ca2+ from blood into bone”
Structure of Parathyroid
4 small glands behind the thyroid
Secretions of Parathyroid and its Results
Secretes: parathyroid hormone (PTH)
Results: increase blood Ca2+ levels
“thyroid produces calcitonin, decreases Ca2+ levels”
“parathyroid found on opposite side of the thyroid. PTH will increase Ca2+ levels”
“PTH breaks down bone. Takes calcium from bone and it causes Ca2+ to be released back into the blood”
Structure of Thymus
Two-lobed gland in front of the heart
Secretion of the Thymus and its Results
Secretes: thymosin
Results: T-cell functional regulation
“large when you are younger, smaller as you grow”
“T-cells = type of WBC. Develops and gets training in thymus”
Structure of Adrenal Gland
Multilayered glands above kidneys
Cortex
Medulla
“suprarenal gland”
Cortex of Adrenal Gland
Outer layer of adrenal gland
Secretions of Adrenal Cortex and its Results
Secretes:
Mineral corticoids (aldosterone [regulates BP by increasing])
Glucocorticoids (cortisol)
Androgens (sex hormones that help promote sex drive)
Results:
Stimulate Na+ reabsorption, K+ secretion in kidneys
Catabolism of fats and proteins, raise blood glucose, stress response
Promotes sex drive
Medulla of Adrenal Gland
Inner core of adrenal gland
Secretions of Adrenal Medulla and its Results
Secretes:
Epinephrine
Norepinephrine
Results:
Increased heart rate
Mobilization of energy sources
Structure of Pancreas
Exocrine and endocrine gland below stomach
Exocrine cells: acinar cells
“releases things into external environment”
“releases a lot of digestive enzymes”
Endocrine cells: Islets of Langerhans
*endocrine = release hormones into blood
Function of Exocrine Cells
Secrete enzymes to GI tract
digestive enzymes
Types of Endocrine Cells
Alpha cells
Beta cells
Delta cells
F cells
Characteristics of Alpha Cells
Secretes: glucagon
“…is secreted when glucose is gone to raise blood glucose levels”
Results:
raises blood glucose
glycogenolysis
“breakdown glycogen”
Characteristics of Beta Cells
Secretes:
insulin
Results:
lowers blood glucose
promotes energy storage
“stores as glycogen”
Characteristics of Delta Cells
Secretes:
somatostatin
“statin stops”
Results:
Inhibits secretion of pancreatic hormone
“alpha and beta cells”
Characteristics of F Cells
Secretes:
pancreatic polypeptide
Results:
Inhibits pancreatic exocrine secretions
“stop and work on your acinar cells and stop them from secreting digestive enzymes”
Testes in Males
Secretes:
Androgens
Results:
Sperm production
Sex drive
Secondary sex characteristics (deepening of voice, muscle development)
Ovaries in Female
Secretes:
Estrogens
Results:
Follicular development (development of follicle/egg)
Secondary sex characteristics (widening of hips, development of breast tissue)
The portal system connects the…
A) hypothalamus and posterior pituitary
B) anterior pituitary and posterior pituitary
C) hypothalamus and anterior pituitary
D) pineal gland and the hypothalamus
Which of the following is not a tropic hormone?
A) GnRH: Gonadotropin releasing hormone
B) TSH: Thyroid stimulating hormone
C) TRH: Thyrotropin releasing hormone
D) PTH: Parathyroid Hormone
Epinephrine is secreted from…
A) Thyroid
B) Adrenal cortex
C) Adrenal medulla
D) Anterior pituitary
Which cells of the pancreas secretes glucagon?
A) Beta cells
B) Delta cells
C) F cells
D) Alpha cells
Oxytocin….
A) originates from the paraventricular nucleus
B) is released by the posterior pituitary
C) is the same as vasopressin
D) all of the above