Chapter 17- Endocrine system Flashcards
Endocrinology
study of structure and function of the endocrine glands and the
diagnosis and treatment of disorders of the endocrine system
Hormone
chemical messenger secreted by cells of an endocrine tissue/gland
into the interstitial fluid that diffuses to the blood capillaries, is transported into the
bloodstream to specific “target” cells, where it binds to a specific receptor and has
an effect on that cell’s physiological activity
Endocrine Glands
pituitary, thyroid, parathyroid, adrenal and pineal glands
Organs with endocrine tissue
hypothalamus, thymus, pancreas, ovaries,
testes, kidneys, digestive tract, heart, adipose tissue and placenta
Tropic hormone
Hormones that act on other endocrine glands/endocrine tissue.
Most are secreted by the anterior pituitary but the hormones the hypothalamus secretes that act on the anterior pituitary gland are also tropic hormones.
Difference between endocrine tissue and gland
gland= directly produces hormone (pituitary)
endocrine tissue= some capacity to produce hormone but has other functions (hypothalamus)
Regulating physiology functions of hormones
-chemical composition of the ECF
-metabolism and energy balance
-biological clock
-contraction of smooth and cardiac muscle
-some immune system functions
Functions of hormones
-regulate many aspects of physiology
-control growth and development
-regulate the reproductive organs
Nervous system vs endocrine system mediator molecules
N= neurotransmitters
E= hormones
Nervous system vs endocrine system site of action
N= close to release site (synapse)
E= far away from release site (anywhere)
Nervous system vs endocrine system types of target cells
N= few cell types, neurons, muscle, glands
E= any body cells
Nervous system vs endocrine system time to onset of action
N= milliseconds
E= seconds to days
Nervous system vs endocrine system duration of action
N= shorter (msec)
E= longer (sec to days
Anterior pituitary physical characteristics
-sits within the sella turcica and sphenoid bone
-attached to the hypothalamus via the infundibulum
-under control of the hypothalamus
-largest portion
Releasing hormones from the hypothalamus
-gonadotropin-releasing hormone
-thyrotropin-releasing hormone
-corticotropin-releasing hormone
-prolactin-releasing hormone
-somatostatin/prolactin-inhibiting hormone
-growth hormone-releasing hormone
posterior pituitary hormones
-oxytocin
-antidiuretic hormone
-produced by neurons in the hypothalamus, stored on posterior, controlled release from neural response
histology of anterior pituitary
Grows upwards from primitive
pharynx during embryological
development, larger portion of
pituitary gland
histology of posterior pituitary
- Grows downwards from the brain;
composed of nervous tissue - Stores hormones made by the
neurons in hypothalamus
7 anterior pituitary hormones
Prolactin (PRL)
Thyroid stimulating hormone (TSH)
Luteinizing hormone (LH)
Follicle-stimulating hormone (FSH)
Growth hormone (GH)
Adrenocorticotrophic hormone (ACTH)
Melanocyte-stimulating hormone (MSH)
Control of Pituitary Secretion (using thyroid hormone as an example)
1) Hypothalamus secretes TRH
2) TRH stimulates anterior pituitary to
secrete TSH
3) TSH stimulates the thyroid gland to
secrete thyroid hormone (TH)
4) TH stimulates metabolism of most cells
in the body
5) TH also inhibits the release of TSH by
the anterior pituitary
6) To a lesser extent, TH also inhibits the
release of TRH by the hypothalamus
Functions of GH-IGF action
1) Protein synthesis
- Tissue repair
2) Lipid metabolism
- Provides energy via fatty
acids + glycerol
- Spares protein
3) Carbohydrate metabolism
- Stimulates glucose
production by liver
4) Electrolyte balance
- Promotes Na+, K+, Cl-
retention by kidneys, increases
Ca2+ absorption by small
intestines
water soluble
-travel freely through blood stream
-no transport proteins
-catecholamines
-peptide hormones
-majority of hormones
