Membrane Transport, Animation
Вставка
- Опубліковано 4 жов 2024
- (USMLE topics) Cell transport: permeability of the cell membrane to various molecules, types of ion channels and transporters.
Purchase a license to download a non-watermarked version of this video on AlilaMedicalMedia(dot)com
Check out our new Alila Academy - AlilaAcademy(dot)com - complete video courses with quizzes, PDFs, and downloadable images.
©Alila Medical Media. All rights reserved.
Voice by: Ashley Fleming
All images/videos by Alila Medical Media are for information purposes ONLY and are NOT intended to replace professional medical advice, diagnosis or treatment. Always seek the advice of a qualified healthcare provider with any questions you may have regarding a medical condition.
All animal cells are enclosed in a plasma membrane, which consists of 2 layers of phospholipids. The hydrophobic nature of the cell membrane makes it intrinsically permeable to small NON-polar and uncharged polar molecules, but NON-permeable to large polar molecules and CHARGED particles. Charged particles, such as ions, must use special channels to move through the membrane.
Transport of a molecule can be passive or active. PASSIVE transport does NOT require energy input because it moves the molecules “DOWNHILL”, for example, from HIGHER to LOWER concentration. ACTIVE transport, on the other hand, moves the molecules AGAINST their gradients and therefore requires ENERGY expenditure.
Ion channels permit PASSIVE transport of ions. These are transmembrane proteins that form PORES for ions to pass through. Most ion channels are SPECIFIC for a certain type of ion.
Ion channels can be classified by how they change their OPEN-CLOSED state in RESPONSE to different factors of the environment. Common types of ion channels include:
LEAK channels: these channels are almost always OPEN allowing more or less steady flow of ions; examples are potassium and sodium leak channels in neurons.
LIGAND-gated ion channels: these channels OPEN upon BINDING of a LIGAND. They are most commonly found at synapses, where neurons communicate via chemical messages, or neurotransmitters. An example is the GABA receptor, a chloride channel located on POST-synaptic neurons. It OPENS upon binding to GABA, a neurotransmitter released by the PRE-synaptic neuron, and allows chloride ions to flow into the cell.
VOLTAGE-gated ion channels: these channels are REGULATED by membrane voltage. They OPEN at some values of the membrane potential and CLOSE at others. These are the channels that underlie ACTION POTENTIALS in neurons and cardiac muscles.
ACTIVE transport of ions is carried out by ion transporters, or ion PUMPS. These are transmembrane proteins that PUMP ions AGAINST their concentration gradient using cellular ENERGY, such as ATP. Most notable example is the sodium-potassium pump which maintains the resting potential in neurons by pumping two potassium IN and three sodium OUT of the cell.
Another type of ion transporters, known as SECONDARY transporters, do NOT use ATP directly. Instead, they move ONE ion DOWN its concentration gradient and use THAT ENERGY to POWER the transport of a SECOND ion. Symporters transport the two ions in the same direction, while antiporters pump the coupled molecule in the OPPOSITE direction.
Love our videos? Check out our new courses made entirely with videos like this (without watermark): www.alilaacademy.com/
This made a lot more sense than the lesson in my school did. Thank you!
All the videos by Alila Medical Media are godsend. They did the best job in explanation.
Thank you! I have finally understand this topic!
Thanks allot for your great effort ... We benefit From your short videos greatly ... Don't stop spreading more of science ... 😃
Greate Video ! Thank you so much for such an explanation.❤
very useful video for beginners
Very helpful, thanks!
Easy to understand thanks for uploading
VERY VERY INFORMATIVE, THANK YOU SOO MUCH
Amazing
Best videos ever!
Thanks
Thanks fot this amazing work
Thanks. I got a clear understanding
Nice
Amazing job...that's
great workkkkkk
Thankyou mam your vidio is very helpful me
Wieso gibts keine deutschen videos das is so ein wichtiges thema
Cool
Wow.
Any ionophores that are available over the counter?
@@izzy0164 Yes there using quercetin is a prophylactic as an ionophore
@@izzy0164 That's correct our local hospitals have been using them as a prophylactic or early treatment protocol. When used early enough it is very effective but must be taken with zinc and I believe they give another anti viral as well
Phys
Endocrine system 🎉