Interview
Transport Across Cell Membranes Notes
- Course
- Institution
Transport Across Cell Membranes Notes
[Show more]
Seller
Follow
marocsofiane
Content preview
Transport Across CellMembranes
The lipid bilayer is only permeable to small and nonpolar substances.
● Oxygen and carbon dioxide are nonpolar gases that freely diffuse from their areas of higher
concentration to areas of lower concentration.
● Steroid hormones have a cholesterol-based structure and are able to pass through cell membranes,
although more recent discoveries have demonstrated that even steroid hormones often make use of
a variety of protein channels and transporters.
● Ethanol alcohol has a slow and limited ability to cross cell membranes, but it does help to explain
some of its toxic effects.
● Even water , although small, is too polar to easily diffuse across the cell membrane.
Passive transport is movement down a concentration gradient.
● Simple diffusion is when the substance can pass through the lipid bilayer .
○ Gas exchange of oxygen and carbon dioxide is the best example for healthcare
students of substances that don’t need a transport channel.
Facilitated diffusion is passive transport that uses a channel.
● Aquaporins are extremely complex channels, formed from the coordinated interaction of 6
different proteins
○ They are inserted into the membrane under the influence of vasopressin - it
allows the body to retain more water in the body and this raises blood pressure.
■ This hormone is also known as antidiuretic hormone (ADH, made in the pituitary gland) to
emphasize that by retaining water , we make less urine.
■ Aquaporins facilitate osmosis, the diffusion of water . The channels allow water to move either
direction. Sometimes water leaves cells, and sometimes it enters cells, always following the rules of
diffusion. Understanding the movement of water under different medical circumstances will help you
learn about fluid shifts such as what occurs in pulmonary edema or circulatory shock.
The benefits of buying summaries with Stuvia:
Guaranteed quality through customer reviews
Stuvia customers have reviewed more than 700,000 summaries. This how you know that you are buying the best documents.
Quick and easy check-out
You can quickly pay through credit card or Stuvia-credit for the summaries. There is no membership needed.
Focus on what matters
Your fellow students write the study notes themselves, which is why the documents are always reliable and up-to-date. This ensures you quickly get to the core!
Frequently asked questions
What do I get when I buy this document?
You get a PDF, available immediately after your purchase. The purchased document is accessible anytime, anywhere and indefinitely through your profile.
Satisfaction guarantee: how does it work?
Our satisfaction guarantee ensures that you always find a study document that suits you well. You fill out a form, and our customer service team takes care of the rest.
Who am I buying these notes from?
Stuvia is a marketplace, so you are not buying this document from us, but from seller marocsofiane. Stuvia facilitates payment to the seller.
Will I be stuck with a subscription?
No, you only buy these notes for $7.77. You're not tied to anything after your purchase.
Can Stuvia be trusted?
4.6 stars on Google & Trustpilot (+1000 reviews)
85443 documents were sold in the last 30 days
Founded in 2010, the go-to place to buy study notes for 14 years now