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What is a Membrane?

A membrane is a thin layer that forms the outer layer of a living cell. The outer layer of the cell is called the plasma membrane, and it encloses rooms called organelles. Thus, this encloses the chambers of the cell. The membrane is known as a biological membrane and cell membrane, too. 

The cell membrane is a semi-permeable membrane that surrounds the cytoplasm of the cell. This means its function is to protect the integrity of the interior cell by allowing certain substances into the cell while keeping the others out. Additionally, it serves as the cell wall in other organisms. 

In this article, we will discuss the different types of membrane. We will also talk about cell membrane functions and structure.


Cell Membrane Function

The biological membrane has three main functions. Here are the functions:

1. Membranes keep the toxic substances out of the cell. 

2. The membranes contain receptors and channels which allow specific molecules like ions and nutrients. They mediate the activity of the cellular and extracellular activities which happen between the cell and the environment on the outside. 

3. Membranes separate vital incompatible metabolic processes which take place within the organelles.

4. A function of the cell membrane is to regulate growth, a balance between endocytosis and exocytosis. 


What is the Plasma Membrane?

Plasma Membrane refers to a thin membrane that surrounds every living cell. It separates the enclosure from any external environment around it. The plasma consists of water-soluble substances like nucleic acids, proteins, and carbohydrates. The plasma membrane is selectively permeable as it allows hydrophobic molecules and tiny small molecules to diffuse through the lipid layer. 

Additionally, it doesn't allow the ions and large polar molecules to pass through the membrane. The function of the cell membrane is different from the plasma membrane function.  However, animal cells, plant cells, and fungal cells have plasma membranes. 


Types of Membrane

The human body has thin membranes like tissues that cover the body, line body cavities, and protect the organs. The membranes can be classified into two categories epithelial and connective tissue membrane. 

  • Epithelial membranes are the ones that consist of epithelial tissues. The connective tissue is attached to it. There are two main types of epithelial membranes, which are mucous membranes and serous membranes. The mucous membranes are the ones that line the digestive tract, respiratory, excretory, and reproductive tracts. The serous membranes line the body cavity, which doesn't open outside. Some places where you will find the serous membranes line the thoracic cavity and cover the lungs. In the lungs, the serous membrane is called the pleura. 

  • Connective tissues membrane lines the connective tissue. There are two main kinds of membranes: synovial membranes and meninges. Synovial members are connective tissues that line the cavities of freely movable joints such as the shoulder, elbow, and knee. It secretes the synovial fluid, which lubricates the cartilage. The meninges are connective tissues that cover the brain and spinal cord. 


Membrane Structure and Functions


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The cell membrane is mainly composed of different kinds of proteins and lipids. Depending on the location of the cell membranes, the lipids make up to 20 to 80 percent of the membrane, with the remainder of the cell. The lipids give the cell membrane flexibility, protein monitor, and maintain the cell's chemical climate. Various kinds of lipids are present in the skin. The lipids present in the skin are phospholipids, cholesterol, and glycolipids. 

Besides the lipids, the cell membrane contains proteins. Membranes consist of peripheral membrane proteins which are connected to the cell membrane by interaction with other proteins. Another kind of protein in the cell membrane is the integral membrane protein. 

The cell membrane's other proteins are the structural proteins, which help support the cell and give it shape. There are cell organelles that are surrounded by the cell membrane. The organelles include the nucleus, endoplasmic reticulum, lysosomes, and Golgi apparatus. Mitochondria and chloroplast are also present, but a double membrane binds them.


Tympanic Membrane

The tympanic membrane is a membrane which you will find in the ear. It's a membrane that separates the middle ear and the External Ear. 

The tympanic membrane is the one that receives and amplifies the sound waves. The central part of the tympanic membrane is known as the umbo. The common name of this membrane is the eardrum. It's the membrane that separates the outer ear from the inner ear.  

When any sound reaches the tympanic membrane, it causes the ear to vibrate. Then, these vibrations are transferred from the tiny bones to the middle ear, transmitting these vibration signals to the inner ear. The tympanic membrane comprises a thin layer of connective tissue membrane, which is covered by the skin on the outside and mucosa on the inside.

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FAQs on Membrane

Q1. Why Do Cells Need Membrane?

All living things are made from cells and all cells have a cell membrane or also called the plasma membrane. This cell membrane is semipermeable in nature which allows the necessary things inside the cell to stop the unwanted and toxic particles from entering it. The membrane also provides a fixed environment to the cell separating it from the external environment. With the help of the membrane, the cell can survive in various environments.

Q2. Is Cell Membrane Amphipathic?

Yes, the formation of the cell membrane takes place with the help of amphipathic molecules. It helps the proteins to have both polar and nonpolar parts of the cell membrane to do their job. Some of them say that the origin of life has started from amphipathic molecules.

Q3. What is the Structure and Function of the Cell Membrane? 

The cell membrane is mainly composed of different kinds of proteins and lipids. Depending on the location of the cell membranes, the lipids make up to 20 to 80 percent of the membrane, with the remainder of the cell. The lipids give the cell membrane flexibility, protein monitor, and maintain the cell's chemical climate. Various kinds of lipids are present in the skin. The lipids present in the skin are phospholipids, cholesterol, and glycolipids. Besides the lipids, the cell membrane contains proteins. Membranes consist of peripheral membrane proteins which are connected to the cell membrane by interaction with other proteins. The cell membrane's other proteins are the structural proteins, which help support the cell and give it shape. There are cell organelles that are surrounded by the cell membrane. The organelles include the nucleus, endoplasmic reticulum, lysosomes, and Golgi apparatus.

Q4. What is Plasma Membrane?

Plasma Membrane refers to a thin membrane that surrounds every living cell. It separates the enclosure from any external environment around it. The plasma consists of water-soluble substances like nucleic acids, proteins, and carbohydrates. The plasma membrane is selectively permeable as it allows hydrophobic molecules and tiny small molecules to diffuse through the lipid layer. The plasma membrane function is to protect the protoplasm. The plasma membrane is found in animals, plants, and some microorganisms. The plasma membrane receives receptors which is not something that the cell membrane can do. This membrane is living and metabolically active.


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