Physeo-Physiology Flashcards
Cellular Membrane Structure
- phospholipids
- 1 hydrophilic phosphate head (H2O) with 2 hydrophobic tails (lipid)
- Hydrophobic tails face each other and form lipid bilayer so lipid soluble substances can cross easily
Lipid soluble substances that cross cell membrane easily
Simple Diffusion
Steroids (including steroid hormones)
Lipids
O2 & CO2
All without acting on a receptor
Water soluble substances
Repelled by lipid bilayer and cant readily cross into the membrane
Charged molecules (H2O, Na+, Cl-, glucose)
Large particles like proteins, they are too large to pass through the hydrophilic heads
Water
On each H there is a + charge so its hard to cross
Na+ and Cl-
Have charges and thus are repelled by the cellular membrane
Glucose
Has partial - charge
Simple Diffusion
No carrier or protein transporter needed
No energy required (passive)
Follows concentration gradient
Substances that use simple diffusion: steroids, lipids, O2, CO2
Carrier-mediated Transport
Has carrier/protein transporter to help it get inside the cell
Conducted via protein and this protein can become saturated and the transport can reach max capacity
Because its a protein it can experience competition
3 types of carrier mediated transport
Facilitated diffusion: like simple diffusion but doesn’t cross membrane freely it needs help (transporter) to get across
Primary active transport: requires ATP because substance is flowing in the opposite direction of concentration gradient. Since its opposite flow it needs energy
Secondary active transport: requires ATP as well
Facilitated diffusion
- Has carrier/protein transporter
- no energy required (passive)
- almost any substance that cant use simple diffusion can use facilitated
(if it needs to go in opposite direction then needs 1 or 2 active transport!)
Primary active transport
Has carrier/protein transporter (like in facilitated diffusion)
ATP is required making it active. Na/K ATPase. ATPase means that ATP is broken down into ADP and P
Moves against gradient, so flows in the opposite direction
Secondary active transport
Has carrier/protein transport
Active, so requires ATP
Moves against concentration gradient but follows Na+ gradient created by primary active transport
Receptor mediated endocytosis
Proteins on ligand bind to proteins on cell surface and then the cell membrane forms coated vesicles that is then ingested
G protein (Gq-alpha)
H1 - histamine a1 - epi, norepi V1 - ADH M1 - acetylcholine M3 - acetylcholine
HAV 1 MM
Hormones:
GnRH, TRH, oxytocin, angiotensin 2, gastrin
Gq-alpha second messenger
Increase IP3
Increase DAG
Activates these two and causes activation of protein kinase C
G protein (Gs-alpha)
D1 - dopamine H2 - histamine V2 - ADH B1 - epi, norepi) B2 - epi
Hormones: LH, FSH, CRH, ADH, ACTH, PTH, hCG, MSH, GHRH, glucagon, calcitonin
Gs-alpha second messenger
Increase cAMP
G protein (Gi-alpha)
M2 - acetylcholine
a2 - epi, norepi
D2 - dopamine
Gi-alpha second messenger
Decrease cAMP
Gq-alpha subunit pathway
G protein coupled receptor
Also has b and g subunits
Goes through conformational change and goes to GTP from GDP
Phospholipase C
Enzyme that cleaves PIP2 into IP3 and DAG
IP3
Binds to endoplasmic reticulum causing it to release Ca2+
Ca & DAG
bind protein kinase C which causes a cellular response
Sympathetic receptors
NE is the primary sympathetic neurotransmitter
Epi is released from adrenal medulla and can stimulate B2 receptors
a1, a2, b1, b2
