Endocrine System Flashcards
Hormones
Always travel through blood
Derived from steroids, proteins, or modified a.a.
Chemical signals
Hypothalamus
Monitors condition of external and internal environment
Stimulates hormone production
Neurosecretory cells
Link hypothalamus to pituitary gland
Built like neurons but secrete hormones instead of NT
Anterior Pituitary
Release tropic hormones (directly affect other endocrine glands)
Releasing hormones made in hypothalamus and release into the blood to go to anterior pituitary
Posterior Pituitary
ADH and Oxytocin produced in hypothalamus by neurosecretory cells, but are stored in posterior pituitary
Do not affect other glands like the ant. pit. but directly affect tissues
Islets and Langerhans
Bundles of cells in the pancreas
Combination of alpha cells and beta cells
Beta Cells
Secrete Insulin
Insulin released when blood glucose is high
Stimulates liver and other body cells to take up glucose
Liver and muscles convert glucose to glycogen
adipose cells convert glucose into fat
Alpha Cells
Secrete glucagon
Stimulates liver to release glucose into bloodstream
Liver also produces and releases glucose by converting a.a./FA into glucose when needed
Steroid Hormones
Diffuses through PM of cell and goes directly into the nucleus
Binds to receptor in nucleus which activates gene transcription
Peptide Hormones
Can’t diffuse through PM
Binds to receptor on membrane (receptor mediated endocytosis)
Second messenger like cAMP or IP3 continue the message
Amino Acid Derived Hormone
Small molecules derived from Tyr and Trp
i.e. EPi, NE, thyroxine, melatonin
Tropic Hormones
Thyroid Stimulating Hormone
Adrenocorticotropic Hormone
Follicle Stimulating Hormone
Luteinizing Hormone
Thyroid Stimulating Hormone (TSH)
Peptide
Target thyroid gland
Thyroid secretes T3 and T4
Adrenocorticotropic Hormone (ACTH)
Peptide
Targets adrenal cortex
Adrenal cortex secretes glucocorticoids (steroid hormones)
Follicle Stimulating Hormone (FSH)
Peptide
Targets follicles (ovaries and testis)
Regulates oogenesis and spermatogenesis
In females, FSH stimulates the maturation of ovarian follicles to secrete estrogen
in males, stimulates maturation of seminiferous tubules and sperm production
Luteinizing Hormone (LH)
Peptide
Targets ovaries and testis
Also regulate oogenesis and spermatogenesis
During follicular phase of ovarian cycle, estrogen levels spike upward, stimulates hypothalamus to produce surge of LH
Surge trigger ovulation
In females, LH stimulates formation of corpus luteum
In males, stimulates interstitial cells of testes to produce testosterone
Prolactin (PRL)
Peptide
Targets tissues in mammary glands
Stimulates milk production
Growth Hormone (GH)
Peptide
Targets bone and muscle
Stimulates growth
Medulla
Amino acid
Releases EPI/NE
Targets blood vessels, heart, liver
Increases blood glucose
Constricts blood vessels (fight or flight)
Cortisol
Steroid
Secreted by Adrenal cortex
Glucocorticoid
Increases blood glucose
Increases absorption of Na
Increases excretion of K
Aldosterone
Steroid
Secreted by adrenal cortex
Mineralocorticoid
Increases blood glucose
Increases absorption of Na
Increases excretion of K
Triiodothyronine (T3), Thyroxin (T4)
Amino acid
Increases cell metabolism
Calcitonin
Peptide
Released when blood P and Ca are high
Thyroid hormone
Targets bone
Decreases blood Ca, increases bone Ca
Parathyroid Hormone (PTH)
Peptide
Thyroid Hormone
Targets bones and increases blood Ca and P, decreases bone Ca and P
Testosterone
Steroid hormone
Targets testis and other general areas
Spermatogenesis
Secondary sex characteristics
Estrogen
Steroid Hormone
Targets uterus and other general areas
Secondary sex characteristics
Rising levels of estrogen stimulate hypothalamus to produce LH surge (triggering ovulation), but not directly responsible for ovulation
Progesterone
Steroid hormone
Targets uterus
Role in menstrual cycle and pregnancy
Melantonin
Pineal gland
amino acid
Regulates circadian rhythm
Targets body in general
Minerals in Bones
Ca and P
Bone Resorption
Done by osteoclasts
Osteoblasts
Build up bone
Connective tissue cell
Secrete osteoid (collagen and mucopolysaccharide)
Osteocyte
Maintains bone tissue
Osteogenic cell
Stem cell
Epiphysis
Wider section at end of bone
Filled with spongy bone
Spaces in spongy bone filled with red marrow
Increased length of bones originates at epiphyseal plate
Medullary Cavity
In diaphysis
Hollow region
Filled with yellow marrow
Has endosteum lining - where bone growth, repair, and remodeling occur
Periosteum
Covers outer surface of bone
Fibrous membrane
Contains blood vessels, nerves, lymphatic vessels
Diaphysis
Tubular shaft of one (middle part)
Walls made of compact bone
C Cells
In the thyroid
Also called parafollicular cells
Produce calcitonin (decreases blood Ca, increases bone)
