Phospholipids and steroids

keypoints; steroids

-cholesterol is a component of the phospholipid bilayer and plays a role in the structure and function of membranes -steroids are found in the brain and alter electrical activity in the brain.

keypoints;phospholipids

-consist of a glycerol molecule, two fatty acids, and a phosphate group -phosphate group is the negatively-charged polar head, which is hydrophilic

cell's plasma membrane

-contains proteins and other lipids -biological membranes remain fluid b/c of unsaturated hydrophobic tails which prevent phospholipid molecules from packing together and forming a solid.

phosphatidate (diaclyglycerol 3 phosphate)

-diacylglycerol does not qualify as a phospholipid, it would then be considered a? - a precursor to phospholipids

cholesterol

-most common steroid and is mainly synthesized in the liver -precursor to vitamin D -precursor to many important steroid hormones --estrogen --testosterone --progesterone

steroids and the cns

-neurosteroids alter electrical activity in the brain -either activate or tone down receptors that communicate messages from neurotransmitters -since neurosteroids can tone down receptors and decrease brain activity, steroids are often used in anesthetic medicines.

triglycerides vs phospholipids

-phospholipids help form diacylglycerol -third carbon of the glycerol backbone is also occupied by a modeified phosphate group

steroid

-play roles in reproduction, absorption, metabolism regulation, and brain activity.

keypoints;phospholipids

-since the heads are hydrophilic, they face outward and are attracted to the ICF & ECF. -if phospholipids are placed in water, they form into micelles

keypoints; steroids

-steroids are lipids b/c they are hydrophobic and insoluble i water, but they do not resemble lipids since they have a structure composed of four fused rings

cholesterol functions

-synthesizes hormones aldosterone --osmoregulation -cortisol --metabolism -bile salts --help emulsify fats and their absorption of cells.

keypoints;phospholipids

-the fatty acid chains are the uncharged, nonpolar tails, which are hydrophobic -since the tails are hydrophobic, they face the inside, away from the water and meet in the inner region of the membrane

hormone

any substance produced by one tissue and conveyed by the bloodstream to another to affect physiological activity.

neurotransmitter

any substance, such as acetylcholine or dopamine, responsible for sending nerve signals across a synapse btwn two neurons

keypoints; steroids

b/c they can tone down receptors that communicate messages from neurotransmitters, steroids are often used in anesthetic medicines.

amphipathic

describing a molecule, such as a detergent, which has both hydrophobic and hydrophilic groups

keypoints; steroids

cholesterol is the most common steroid and is the precursor to vit d, testosterone, estrogen, progesterone, aldosterone, cortisol, and bile salts.

two important phospholipids that are found in pm

phosphatidylcholine & phosphatidylserine

lipid tails

some contain saturated fatty acids and other contain unsaturated fatty acids

lipid bilayer

-acts as a semipermeable membrane -only lipophilic solutes can easily pass the phospholipid bilayer

structure of steroids

-all steroids have four linked carbon rings, and many of them have a short tail. -many steroids have the OH functional group -classified as alcohols called sterols

Phospholipids

-amphipathic molecules that make up the bilayer of the plasma membrane and keep the membrane fluid.

micelle

lipid molecules that arrange themselves in a spherical form aqueous solutions

osmoregulation

the homeostatic regulation of osmotic pressure in the body in order to maintain a constant water content