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EdrawMindPhysiology Section 1 Basic structure and material transport function of cell membrane
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Physiology Section 1 Basic structure and material transport function of cell membrane
According to the 14th Five-Year Plan Blue Skin Physiology, the cell membrane is the peripheral barrier of the cell and has a special structure and function. Its basic structure is mainly composed of lipids and proteins, forming a liquid mosaic model.
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Physiology Section 1 Basic structure and material transport function of cell membrane
- bacteria
This is a mind map about bacteria, and its main contents include: overview, morphology, types, structure, reproduction, distribution, application, and expansion. The summary is comprehensive and meticulous, suitable as review materials.
- Plant asexual reproduction
This is a mind map about plant asexual reproduction, and its main contents include: concept, spore reproduction, vegetative reproduction, tissue culture, and buds. The summary is comprehensive and meticulous, suitable as review materials.
- Reproductive development of animals
This is a mind map about the reproductive development of animals, and its main contents include: insects, frogs, birds, sexual reproduction, and asexual reproduction. The summary is comprehensive and meticulous, suitable as review materials.
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Section 1 Basic structure and material transport function of cell membrane
basic structure of cells
cell membrane
concept
Boundaries of the cell as a basic living system
The main function
Barrier between cells and the external environment
Separating intracellular fluid from extracellular fluid ensures the relative stability of the internal environment of the cell
Controlling the movement of substances in and out of cells (permselectivity)
exchange information between cells
Chemical composition and molecular arrangement
(1) Unit membrane
The cell membrane and various membranous structures within the cell all have the same basic structural form similar to a triple plate, which is called...
(2) Chemical composition
Protein 55%
Lipids
Phospholipids 25%
Cholesterol 12%
Its existence ensures the relative fluidity of the cell membrane
Cholesterol content is inversely related to mobility
Other lipids 4%
Sugar 3%
negative charge
(3) Molecular arrangement
pedestal
liquid lipid bilayer
Phospholipids
Phosphate group (hydrophilic) + hydrocarbon chain (hydrophobic)
Protein embedded in it
Sugar molecules bind to lipids and proteins and attach to the outer surface of the membrane
2. Material transport function of cell membrane
Factors affecting the diffusion rate of substances
power
concentration difference
condition
The permeability of the membrane to the substance
Ion diffusion is also affected by the electric field force on both sides of the membrane
Classification
Passive transport (small molecules, no energy consumption)
(1) Simple diffusion
1. definition
Diffusion of fat-soluble substances directly through the membrane lipid bilayer along the concentration difference
2. Include
O2, CO2, NH3 and other fat-soluble gases
Steroids (hormone-like)
uncharged polar small molecules
H2O
Also available through water channel
(2) Facilitated diffusion
Non-lipid-soluble small molecules diffuse across the membrane along the concentration gradient/potential gradient with the help of membrane proteins.
No energy consumption
Classification
Facilitated diffusion via channels
Na⁺ K⁺ Ca²⁺
characteristic
Ion channel selectivity
Gating properties
voltage gated channel
Ungated channel
always open
Potassium leak channels on nerve fibers
water channel
aquaporin
In the plasma membrane of some cells, there are a large number of water channels that are highly permeable to water and are always open.
Chemical····
mechanical····
three states
spare
activation
inactivate
Facilitated diffusion via carrier
Carrier/Transporter Classification
unitransporter
Only transport one substance
symporter
sodium glucose symporter
antiporter
Sodium-hydrogen exchanger, sodium-calcium exchanger
The transmembrane transport of water-soluble small molecule substances along a concentration gradient mediated by carrier proteins
glucose, amino acids
Features
structure specificity
saturation phenomenon
competitive inhibition
(3) Active transport
Features
Energy consumption
Reverse electrochemical gradient
Requires help from membrane proteins - pumps (proton pump, calcium pump)
Cell membrane proteins that mediate active transport processes are called ion pumps
sodium potassium pump
(sodium pump, sodium-potassium-ATPase)
effect
Pump Na⁺ out of cells against the concentration gradient
At the same time, extracellular K⁺ is pumped in against the concentration gradient
substance
Protein with ATPase activity
A net increase in extracellular positive ions increases the potential
electrogenic sodium pump
calcium pump
hydrogen pump
Classification
primary active transport
Direct use of ATP for transport against concentration gradients
sodium potassium pump
secondary active transport
Features
Relies on primary active transport for energy
Transporting ≥2 types at the same time
Classification
forward cotransport
reverse cotransport
Example
Intestinal epithelial cells absorb glucose and amino acids
Glucose reabsorption by renal tubular epithelial cells
(4) Membrane vesicle transport
Coming out of the cell
Remove macromolecular material clumps
eg. Secretory activity of gland cells, release of neurotransmitters
Entry/endocytosis
eg. Microorganisms, proteins, etc.
Devour
solid
swallow
liquid
Summarize