Endocrine System Flashcards
What brings in homeostasis?
Endocrine system and the nervous system
What methods does the endocrine and nervous system use?
communication that affect specific target organs
EXOcrine glands are….
secretions released into ducts opening onto an epithelial surface
ENDOcrine glands are…
ductless organs that secrete their molecules directly into the bloodstream
What happens if an organ lacks a SPECIFIC receptor?
It does NOT respond to its stimulating effects
Peptide hormones
formed from chains of amino acids
most of our body’s hormones are peptide hormones
ex: growth hormone
What are longer chains of peptide hormones called?
Protein hormone
Steroid hormones
type of lipid derived from cholesterol
ex: testosterone
Biogenic amines
small molecules produced by altering the structure of a specific amino acid
ex: thyroid hormone
What is negative feedback loop?
A stimulus starts a process, and eventually the hormone secreted or a product of its effects causes the process to slow down or turn off
What is an example of negative feedback loop?
regulation of the blood glucose level
Positive feedback loop
Accelerates the original process, either to ensure that the pathway continues to run or to speed up its activities
What is an example of positive feedback loop?
milk release from mom’s boobies
Master Control Center of endocrine
hypothalamus
Hormone in the hypothalamus…
secrete hormones that influence the secretory activity of the anterior pituitary gland
Regulatory hormones
secreted into the blood to regulate secretion of most anterior pituitary hormones
Hypothalamus has _______ over these endocrine organs
Indirect control
What two hormones are transported into the posterior pituitary?
oxytocin antidiuretic hormone (ADH)
Pituitary Gland (Hypophysis)
Small, slightly oval gland housed within the hypophyseal
Covered superiorly by the diaphragma sellae
Connected to the hypothalamus by a thin stalk, the infundibulum.
Partitioned both structurally and functionally into an anterior pituitary and a posterior pituitary
What is the pituitary gland controlled by?
regulatory hormones secreted by the hypothalamus
How do hormones reach the anterior pituitary?
via hypothalamo- hypophyseal portal system
What is hypothalamo-hypophyseal portal system?
“shunt” that takes blood carrying regulatory hormones from the hypothalamus directly to the anterior pituitary
What does the Thyroid Gland look like?
Butterfly
Where do the left and right lobes connected at?
The anterior midline by a narrow isthmus
Where is the Thyroid cartilage located?
inferior to the thyroid cartilage of the larynx
anterior to the trachea
Where are the Parathyroid Glands located?
posterior surface of the thyroid gland
What are the two cells in the parathyroid gland?
chief and oxyphil cells
What do the chief cells do?
- source of parathyroid hormone (PTH).
- stimulates osteoclasts to resorb bone and release calcium ions from bone matrix into the bloodstream
- stimulates calcitriol hormone synthesis in the kidney
- promotes calcium absorption in the small intestine
- prevents the loss of calcium ions during the formation of urine
What do the oxyphil cells do?
is not known
What are Adrenal Glands (suprarenal)?
Paired, pyramid-shaped endocrine glands on the superior surface of each kidney.
Covered in fat and fascia to minimize their movement
Why is the Adrenal Cortex yellow?
due to stored lipids in its cell
What does the Adrenal Cortex synthesize?
more than 25 different steroid hormones, called corticosteroids
How is corticosteroid synthesis stimulated?
ACTH produced by the anterior pituitary
What does the Adrenal Cortex regulate?
Regulates salt, sugar, and sex!
Adrenal Medulla forms…..
inner core of each adrenal gland
What are chromaffin cells?
clusters of large, spherical cells
What is adrenaline?
innervated by the sympathetic division of the ANS, one population of cells secretes the hormone epinephrine
What is nonadrenaline?
other population secretes the hormone
What do hormones prepare the body for?
Emergency or fight-or-flight situation.
Where is the pancreas located?
between the duodenum of the small intestine and the spleen
What is the pancreas mainly composed of?
pancreatic acini
What do pancreatic acini produce?
alkaline pancreatic juice that aids digestion
What are pancreatic islets? (islets of Langerhans)
Small clusters scattered among the pancreatic acini
Pancreatic islets are composed of four types
two major types (called alpha cells and beta cells)
two minor types (called delta cells and F cells)
ALPHA cells secrete GLUCAGON when…..
blood glucose levels DROPS
BETA cells secrete INSULIN when…..
blood glucose levels are ELEVATED
DELTA cells are stimulated
by high levels of nutrients in the bloodstream
F cells are stimulated….
by protein digestion
What is pineal gland?
is a small, cone-shaped structure attached to the posterior region of the epithalamus
What do pineal gland secrete?
melatonin
What does melatonin do?
- helps regulate a circadian rhythm (24-hour body clock) –responsible for FSH and LH synthesis
- has a role in sexual maturation however not yet understood
Where is the thymus located?
within the mediastinum superior to the heart, posterior to the sternum
The thymus gets smaller as we…
age
What does the thymus do?
associates with the lymphatic system to regulate and maintain body immunity
What two hormones does the thymus produce?
thymopoietin and thymosins
What is T-lymphocytes? (thymus-derived lymphocytes)
hormones stimulate and promote the differentiation, growth, and maturation of a category of lymphocytes
