Quiz 1 Flashcards
When does diffusion occur faster?
When the concentration gradient is greater, the distance is shorter, temperature is higher, molecules are smaller
What is Ficks Law of Diffusion
rate of diffusion=
(surface area)(concentration gradient)(membrane permeability)/ membrane thickness
also: J=PA(Co-Ci)
An increase in membrane thickness will result in a decrease in rate of diffusion.
Define Ligand
Binds to Receptor (estrogen is the ligand for the estrogen receptor)
What is allosteric inhibition/ modulation?
some proteins have alternative sites for regulatory ligands. These sites will either activate or inhibit the protein.
Modulation by phosphorylation
many proteins are activated/ inactivated by the covalent addition of phosphate group. The negative charge from PO42- will pull positive ligands to bind.
How much ATP is used per day in a human
44 lbs
Define -crine, cytokine, hormone, synapse and systemic
-crine: to secrete
Cytokine: chemical used for communication between cells (locally)
Hormone: a chemical secreted into the blood stream to accomplish communication over long distances
Synapse: physical junction between 2 cells
Systemic: all over the body
Define Endo-, Exo-, Endogenous/Exogenous
Endo- within
Exo- without
Endogenous: coming from within (made within your body)
Exogenous: coming from outside (supplements)
What is a Gap Junction?
Space between two neighboring cells that allow for communication/diffusion
What are contact dependent signals?
molecules on the surface of 1 cell interact with molecules on the surface of another
What is local communication in cell-to-cell communication?
One cell secretes a chemical into the extracellular fluid, it is detected by a neighboring cell
What is long distance communication in cell-to-cell
a combination of electrical and chemical signals that travel along nerve axons.
What are Endocrine Cells
They secrete chemical messengers into blood stream, have effects all over the body, used for long-distance communication
Endocrine with Breast Tissue and Estrogen/Progesterone
1) breast tissue has receptors for estrogen and progresterone
2) estrogen released into blood, accesses all cells of the body
3) estrogen triggers breast cell reproduction, tissue growth and prep for lactation
4) if patients are given estrogen after menopause, it triggers these responses by breast tissue-can lead to breast cancre
What are the differences between cytokines and hormones?
cytokines usually work in short distances
cytokines work on many cell types and are made on demand (never stored)
Cytokines often work locally, hormones always systemically
Define Plasma membrane receptors
transmembrane proteins that bind a lipophobic ligand on the outside and transmit the signal intracellularly
Define Intracellular receptors:
reside in the cytosol or nucleus. Bind Lipophilic Ligands like Steroids. Bind ligand, regulatory elements and DNA
What are up and down regulation?
up-regulation- increase # of receptors for ligands
Down-regulation- decrease # of receptors by pulling them in
Is Cocaine abuse an example of up or down regulation for dopamine receptor expression? Explain
Down Regulation. Results in dependency as your body cannot mimic the amount of dopamine that the cocaine brought in.
Is Oxytocin receptor expression during pregnancy an example of up or down regulation?
Up Regulation: Allows the uterus to become more sensitive to a hormone that is used for other purposes between pregnancies.
Define Agonists and Antagonists
Agonist: exciters, mimic signal molecules and cause action
Antagonist: inhibitors, block receptor and signal pathway
What are tropic hormones?
stimulate other glands to make and release hormones, usually also triggers growth of target gland
Define Primary and Secondary hyposecretion
Primary-
damage to the gland= less hormone produced; enzyme deficiency= less hormone produced; dietary deficiency of iodine=less thyroid hormone produced
Secondary- too little tropic hormone produced/released
Define Primary and Secondary hypersecretion
Primary- endocrine cell tumor=produces hormone out-of-control
Secondary- excessive stimulation by tropic hormones
What are the 3 structural forms of hormones?
Amine, Peptide/protein, and Steroid
Define Amine, Peptides, and Steroid
Amine: small hormones, derivatives of single amino acid
Peptide: somewhat larger (many amino acids) usually produced in an inactive form and activated upon need
Steroid: derived from cholesterol, lipid based. Made in only a few glands in the body. Sex hormones. Can pass through bilayer.
How/where are steroid hormones made and transported?
Steroid hormones are lipophilic meaning they cannot be stored, they must be made on demand; resulting in a slower response time.
They are transported in the blood on albumin or other protein transporters
Made in Adrenal cortex and gonads
What is released from the adrenal cortex and medulla?
Cortex: mineralocorticoids, glucocorticoids, androgens
Medulla: epi and norepi
What is aldosterone?
Major mineralocorticoid,
regulates salt reabsorption during urine formation,
impacts potassium secretion,
therefore central regulator of blood pressure
What is cortisol?
Main glucocorticoid
Regulates sugar use and storage during stress responses
Causes systemic vasoconstriction and therefore high BP
Potent effects on the immune system, anti-inflammatory
Almost every cell type in the body expresses glucocorticoid receptors.
What are Androgens?
DHEA and Androstenedione- precursors to testosterone and estrogen
Functions in sex drive, development of fetus, and puberty
How are hormones broken down and excreted?
Largely by the liver and kidneys (hours to days)
Sometimes metabolized by target cell
Some hormones are broken down by enzymes in tissues and blood (minutes to hours)
Mechanism of Hormone Action
-Reach all cells but only cells with receptors will respond (target cells)
-Receptors are on the surface for water-soluble hormones, intracellular for lipid soluble
-Intracellular receptors are generally transcription factors, so these hormones usually enact changes on gene expression
-Surface receptors often are connected via signaling pathways and may have a variety of effects on the cell.
What controls hormone secretion (3 ways) ?
1) they monitor the blood and release the hormone in response to change in plasma concentration of some substance
2) a neuron stimulates them to release hormone
3) they are controlled by a tropic hormone(hypothalamus and pituitary)
How does the hypothalamus oversee the endocrine system?
1) influences hormone secretion activity of anterior pituitary via tropic hormones
2) produces hormones itself, released from the posterior pituitary
3) oversees hormone secretion by the adrenal gland (medulla)
What functions do the frontal lobe and limbic system serve?
Frontal lobe: decision making and cognitive function
Limbic system: the part of the brain involved in our behavioral and emotional responses
How is the hypothalamus connected to the anterior pituitary ? How does the hypothalamus trigger the anterior pituitary?
Via a portal capillary system. Hypothalamus secretes tropic hormones which trigger endocrine responses in the anterior pituitary.
What is a portal venous system?
this occurs when a capillary bed pools into another capillary bed through veins without firs going through the heart.