Endocrine System Pt.1 Flashcards
What is direct communication?
Exchange of ions and molecules b/w adjacent cells through gap junctions
between cells of the same type
What is paracrine communication?
When chemical signals transfer info from cell to cell w/n a single tissue
Transmission is through extracellular fluid to specific receptors on target cells
What is autocrine communication?
Messages that affect the same cell that secrete them
What is endocrine communication?
Communication by endocrine cells that release hormones that are transported in the bloodstream
Alters metabolic activity of many organs
Their target cells have receptors that read the hormonal messages
What are exocrine glands?
Glands that release their contents through a duct that leads to epithelial surface
What are merocrine glands?
Exocrine glands that release part of their contents by exocytosis (sweat and salivary glands)
What are apocrine glands?
Exocrine glands where part of the cell is pinched off and becomes the secretion (mammary & odorous sweat glands)
What are holocrine glands?
Exocrine gland where mature cell dies and becomes the secreted product (sebaceous glands)
What are the three classes of hormones in the body?
Amino Acid Derivatives
Peptide Hormones
Lipid Derivatives
What are Amino Acid Derivatives?
Small hormones related to amino acids.
Derivatives of tyrosine and tryptophan
What are peptide hormones?
Chains of amino acids, Glycoproteins, and small proteins
and includes all hormones secreted by the hypothalamus, heart, thymus, GI, pancreas, posterior pituitary.
What are glycoproteins?
Proteins that have more than 200 amino acids that have carbohydrate side chains (TSH,LH, FSH)
What are examples of small proteins?
Insulin
GH
Prolactin
What are lipid derivatives?
Hormones that coordinate cellular activity and affect enzymatic processes (blood clotting)
What type of hormones are steroid hormones and what are some examples?
Lipid derivatives that come from cholesterol;
Androgens from testes in males
Estrogen and progesterone from ovaries in females
Corticosteroids from adrenal complex
Calcitriol from kidneys
How do catecholamines and peptide hormones function in the body?
Not lipid soluble, unable to penetrate plasma membrane, and bind to receptor proteins on extracellular receptors
How do Steroid and thyroid hormones function in the body?
They are lipid soluble and diffuse across plasma membrane and bind to receptors inside the cell.
How long are free hormones functional in the body and why?
Less than an hour;
They diffuse out of bloodstream and bind to target receptors
are absorbed and broken down by liver and kidneys or
are broken down by enzymes in blood or interstitial fluids
What are G protein coupled receptors and how do they work?
A hormone binds to an extracellular receptor and activates a G-Protein which when activated, increases cyclic AMP levels which acts as a second messenger within the cell
What are the effects of secondary messengers such as cAMP?
Activation of enzymes or opening ion channels that may accelerate metabolic activity of the cell
(Epinephrine, norepinephrine, calcitonin, parathyroid hormone, ADH, ACTH, FSH, LH, TSH)
How do steroid hormones affect DNA transcription?
Alters synthesis of enzymes or structural proteins because they directly affect activity and structure of target cell.
What is down regulation of a hormone?
Presence of a hormone triggers a decrease in number of hormone receptors and when they’re too high, cells become insensitive to it.
What is up regulation of hormones?
Absence of the hormone creates and increase in the receptors for it and become extra sensitive to the hormone
What is humoral stimuli?
Change in extracellular fluid
What is hormonal stimuli?
arrival or removal of a hormone
What is neural stimuli?
neurotransmitters
What does the pituitary gland do?
Releases nine important peptide hormones
What is the pituitary gland and adrenal gland controlled by?
The hypothalamus
What two hormones does the posterior pituitary gland release?
Antidiuretic Hormone / vasopressin (ADH) and oxytocin (OXT)
What organ(s) does ADH (Vasopressin) directly affect?
Sent out when blood osmolarity increases (negative feedback);
Blood vessels contract and increase blood pressure
Kidneys (increased water reabsorption)
What organ(s) does Oxytocin directly affect and how?
Mammary glands by allowing milk to be ejected.
Uterus (positive feedback) by contracting the uterus and dilating cervix (pushes baby out)
