The endocrine system Flashcards
Includes all the organs that release chemical signals that circulate in the blood (hormones and neurohormones)
endocrine system
What are the 3 major classes of hormone?
steroid, protein and peptide, amine hormones
-are derived from cholesterol and are nonpolar and lipid-soluble.
- can diffuse freely across membranes
steroid hormones
where are the steroid hormone receptors found?
within the ICF of target cells
are steroid hormones stored within endocrine cells? why or why not?
No, they are synthesized and released on demand
Their amino acid sequences are specified by genes, which are transcribed and translated. After synthesis, they undergo processing in which their structure is modified. (type of hormone)
protein and peptide hormone
newly synthesized structure made from protein and peptide hormones? and what does it contain?
preprohormone; a signal peptide
What does the signal peptide do in the preprohormone?
directs synthesis to the ER rather than the cytosol.
once the signal peptide is removed from the preprohormone it becomes a what? which is??
prohormone; inactive
What happens to the prohormones? Where do they go?
they are packaged into vesicles within the golgi apparatus
receptors of this hormone are embedded in target cell membranes
the hormones are water-soluble and cannot cross membranes.
protein and peptide hormones
derived from the amino acids tyrosine or tryptophan.
- properties vary
-typically stored after synthesis and released when endocrine cell is stimulated
amine hormones
What is the primary determinant of the strength and duration of the target cell response?
conc of hormone in the ECF
What is hormone concentration determined by?
- rate of release from endocrine cells
- rate of removal from the ECF
The rate of removal is normally ________. While the rate of release ______ and is regulated by sensory receptors.
constant; varies
an expression of the persistence of a hormone within the ECF
Half-life
the amount of time it takes for half of hormone molecules to be removed from the blood
half-life
Half-life varies between __________ and can be influenced by its ________ ____ ___________ in the blood.
hormones; mode of transport
How does a carrier protein effect half-life?
if a hormone is bound to a carrier protein, its half-life is extended considerably
increase the solubility of nonpolar hormones, allowing increased conc of these hormones in the ECF.
carrier proteins
small region within the inferior part of the brain
hypothalamus
the hypothalamus is connected to the pituitary gland by a narrow stalk called the
infundibulum
The pituitary gland is divided into two lobes called the _________ and ___________ lobes
anterior; posterior
this lobe is made of neural tissue; the other lobe is made of endocrine cells
posterior lobe; anterior lobe
made of neurosecretory cell axon terminals and associated capillary networks.
posterior lobe
the cell bodies of the neurosecretory cells are located within the hypothalamus and are localized in two clusters:
paraventricular nucleus (PVN) and the supraoptic nucleus (SON)
PVN and SON produce the peptide hormones ____ and ____________
oxytocin and anti-diuretic hormone (ADH)
best known for its effect during childbirth and lactation (in humans)
oxytocin
regulates blood vol thru its effects on the kidneys.
ADH
These hormones are released from axon terminals within the posterior lobe
oxytocin and ADH
Made of endocrine cells and produces six different hormones
anterior lobe
What are the two categories of hormones released by the anterior lobe?
direct-acting hormones and tropic hormones
What are the two direct-acting hormones? What does it mean by direct-acting?
growth hormone (GH) and prolactin; they exert their effects on non-endocrine organs.
regulates growth and nutrient metabolism in many tissues, particularly fat and skeletal muscle.
growth hormone (GH)
stimulates milk synthesis in lactating females
prolactin
What are the four tropic hormones?
adrenocorticotropic hormone (ACTH), luteinizing hormone (LH), follicle-stimulating hormone (FSH), and thyroid stimulating hormone (TSH).
What does it mean by tropic hormones?
they regulate the functions of other endocrine organs
affects glucocorticoid hormone production in the adrenal cortex
ACTH adrenocorticotropic hormone
affect sex hormone and gamete production in the gonads
LH luteinizing hormone and FSH follicle-stimulating hormone
affects thyroid hormone production in the thyroid glands
TSH thyroid stimulating hormone
What is hormone production by the anterior lobe regulated by?
neurohormones produced by the hypothalamus
What makes the cells from the anterior lobe diff from those that produce ADH and oxytocin?
-neurosecretory cells are located within hypothalamus
-neurohormones released into portal veins
carry blood directly to anterior lobe (part of special capillary network)
portal veins
