ENDOCRINE SYSTEM Flashcards
is composed of a group of tissues that produce
hormones directly into circulation to travel and act on distant target
tissues/organs
endocrine system
is typically a ductless gland (e.g.
pituitary, thyroid) that releases its hormones into
capillaries that permeate the tissue
endocrine tissue
act on their target cells by
binding to receptors located on the cell surface; e.g.
adrenocorticotropic hormone (ACTH) from the pituitary,
insulin from the pancreas, and parathyroid hormone (PTH)
protein/polypeptide hormones
are cholesterol
derivatives, and include products of the adrenal cortex, ovaries, and testes,
as well as the related molecule vitamin D. These hormones are rapidly
synthesized from cholesterol by series of enzymatic reactions and stored
intracellularly in the tissue of origin
steroid hormones
made by chemical
modification of amino acids, mainly tyrosine
Modified Amino Acid Hormones
- links the nervous system to the endocrine system
via the pituitary gland - is responsible for the regulation of
certain metabolic processes and other activities of the autonomic nervous
system.
Hypothalamus
hormones of hypothalamus
- stimulates ACTH release (adenohypophysis)
Corticotropin-RH
hormones of hypothalamus
- stimulates FSH, LH release (adenohypophysis)
Gonadotropin-RH
hormones of hypothalamus
- stimulates GH release (adenohypophysis)
Growth Hormone-RH
hormones of hypothalamus
- somatostatin; inhibits GH release (adenohypophysis)
GH-inhibiting hormone
hormones of hypothalamus
- stimulates TSH release (adenohypophysis)
Thyrotropin-RH
hormones of hypothalamus
- dopamine; Inhibits prolactin release (adenohypophysis)
Prolactin-IH
- it is anatomically and functionally related to the
hypothalamus. It also called hypophysis, is an essential gland of the body
and sometimes referred to as the “master gland”, because it can control
several of the other hormone glands - bean-sized organ suspended from
the hypothalamus by a stem called the infundibulum (pituitary stalk)
Pituitary Gland
lobes of pituitary gland
- composed of
neural tissue
posterior pituitary (or neurohypophysis)
lobes of pituitary gland
- composed of
glandular tissue
anterior pituitary (or adenohypophysis)
lobes of pituitary gland
- between the posterior and anterior
lobes, synthesizes and secretes melanocyte-stimulating hormone (MSH).
intermediate lobe
Neurohypophysis Hormones
- stimulates uterine contraction, milk let-down (uterus, mammary
glands)
Oxytocin
Neurohypophysis Hormones
- vasopressin; conserves water, reduces urine volume (kidney);
constricts vessels to raise blood pressure (arterioles)
Antidiuretic hormone (ADH)
Adenohypophysis Hormones - stimulates cortical development, glucocorticoid release (adrenal
cortex)
Adrenocorticotropic hormone (ACTH)
Adenohypophysis Hormones - stimulates follicular development (ovary), sperm development (testes)
Follicle-stimulating hormone (FSH)
Adenohypophysis Hormones - lutropin; stimulates ovulation, development of corpus luteum,
secretion by corpus luteum (ovary), secretion of androgens (testes)
Luteinizing hormone (LH)
Adenohypophysis Hormones - somatotropin; Promotes growth in immature animals; metabolic
effects on carbohydrate, lipid, protein metabolism in adults
Growth hormone (GH)
Adenohypophysis Hormones - stimulates release of thyroid hormones (follicular cells of thyroid
gland)
Thyroid stimulating hormone (TSH)
Adenohypophysis Hormones - promotes lactation (mammary gland), maternal behavior (central
nervous system)
Prolactin (PRL)
are small, triangular-shaped glands located on top
(cranial) on both kidneys. They produce hormones that help in regulating metabolism, immune system, blood pressure, and responses to stress, and
other essential functions
Adrenal Gland
each adrenal gland has an ________ that secretes steroid hormones
outer cortex
each adrenal gland has an ________ that secretes adrenaline
inner medulla
Adrenal Cortex Hormones - essential for normal response to stress; important roles in protein, carbohydrate metabolism (multiple organs including liver)
Glucocorticoids
Adrenal Cortex Hormones
- aldosterone; conserve Na, eliminate K (kidney)
Mineralocorticoids
Adrenal Medulla Hormones - augments sympathetic response to stress by actions on several
organs
Epinephrine, Norepinephrine
is a butterfly-shaped organ located in the base of the neck.
Thyroid Gland
cells of thyroid gland
- produce hormones responsible in
controlling metabolism
follicular cells
cells of thyroid gland
- produce hormone responsible in
calcium (Ca) regulation.
parafollicular cells
Thyroid Follicular Cells
- increases oxygen consumption, ATP generation (almost all cells)
- Triiodothyronine (T3)
- Thyroxine (T4)
Thyroid Parafollicular Cells
- promotes calcium retention (bone)
Calcitonin
are embedded in the connective tissue capsule on
the posterior surface of the thyroid glands. They produce hormones important in
regulating Ca in the body.
Parathyroid Gland
Parathyroid hormone
- promotes increase in plasma calcium, reduction in plasma
phosphate (bone, kidney)
Parathyroid hormone
involves a response that is the reverse of the change detected (it functions to reduce the change)
negative feedback mechanism
involves a response that
reinforces the change observed – by amplifying the change.
positive feedback mechanism
