Terms Flashcards
Physiology
science of the function of living systems
Organism
body made up of organs, organelles, or other parts that work together to carry on the various processes of life
Endocrinology
branch of biology and medicine dealing with the endocrine system, its diseases, and its specific secretions called hormones, the integration of developmental events such as proliferation, growth and differentiation (including histogenesis and organogenesis) and the coordination of metabolism, respiration, excretion, movement, reproduction, and sensory perception dependent on chemical cues, substances synthesized and secreted by specialized cells
Parenchyma
functional tissue of an organ
Stroma
the connective tissue or framework of an organ; contains blood vessels, nerves
Capsule
surrounds gland
Trabeculae (septa)
divide glands into lobes or lobules
Endocrine vs. Nervous system
anatomically discontinuous but otherwise similar; both are major communication systems, integrate stimuli and responses to changes in external and internal environment, both are crucial to coordinated functions of highly differentiated cells, tissues, and organs
Principal functions of the endocrine system
maintains homeostasis; integration and regulation of growth, metabolism and development; control, maintenance and instigation of sexual reproduction, including gametogenesis, fertilization, fetal growth and development and nourishment of the newborn
Endocrine secretion
secreted into blood; binds distant target cells
Paracrine secretion
acts locally by diffusing from its source to target cells in the neighborhood
Autocrine secretion
acts on same cell that produced it
General principles of endocrine glands
ductless; highly vascular; functional secretory cells are usually epithelial
Types of endocrine organ arrangements
Discrete glands (thyroid) Endocrine components of other organs (pancreas, gonads, ovaries, testis) Scattered cells throughout other organs (C cells in thyroid)
Classes of hormones
Steroids, protein/peptide hormones, amino acid analogues and derivatives
Steroids
originate from cholesterol precursor
organs- ovaries, testis, adrenal cortex
specific hormones- mineralcorticoids, glucocorticoids, testosterone and estradiol
made- on demand, not stored; steroid producing cells have high levels of SER, Golgi
Protein/peptide hormones
organs- anterior pituitary, thyroid, parathyroid, pancreas
specific hormones- insulin, prolactin, parathormone
protein-hormone producing cells have high levels of RER
Amino acid analogues and derivatives
organs- thyroid and adrenal medulla
specific hormones- thyroxine, norepinephrine, epinephrine (catecholamines)
stored in granules
Types of control mechanisms
External stimuli (cold, light, etc); Internal stimuli (blood sugar, hormonal signals); feedback loops
Types of Hormone receptors
membrane receptors, cytoplasmic/nuclear receptors
Intracellular receptors (cytoplasmic/nuclear)
characteristic of steroid/thyroid hormones
diffuse through plasma membrane
bind to receptor; receptor-hormone complex binds specific DNA sequences
directly alters gene expression
new mRNA and proteins made, new proteins change cell function
Membrane receptors
used by hormones that cannot diffuse through plasma membrane (amines, peptides, proteins)
does not directly alter gene expression
G proteins in cell membrane are activated
1st messenger is hormone, 2nd messenger may be cAMP, cGMP, Ca++
Lumen
inner open space or cavity of a tubular organ
