Specific learning objectives At the end of the
Specific learning objectives At the end of the class You must know. . § § § Define active transport across the cell membrane Name the common ion channel in the cell membrane Name the different type of carrier protein with example § § Classify the different active transport process Explain the types of active transport mechanism
Active Transport This is gonna be hard work!! cell does use energy by the help of Protein Pumps high low
Active transport Energy is required for carriers to transfer substance uphill against a concentration gradient Ex: uptake of iodine by thyroid gland cells
Carrier protein Carriers protein that carry the molecules into or out of the cell through cell membrane q If the more than one molecules are carried by the carrier protein in the same direction either into or out of the cell, the process is called symport or co-transport.
q If the carrier protein carry only one kind of molecule in the same direction either into or out of the cell, this process is called uniport
q If the carrier protein carry more than one molecule in oposite direction either into or out of the cell, the process is known as antiport or counter transport Ex: Na+-K+ ATPase pump
TYPES OF ACTIVE TRANSPORT FPRIMARY ACTIVE TRANSPORT FSECONDARY ACTIVE TRANSPORT
Primary active transport Ø Energy is required directly to move a substance uphill Ø Hydrolysis of ATP by the transporter provides the energy for primary active transport Ø Major primary active transport proteins found in cells are 1 Na+/K+ ATPase 2. Ca 2+ ATPase 3. H+ ATPase 4. H+/K+ ATPase
ØSodium –potassium pump - Is present in all the cells of the body - Responsible for maintaining the Na+ and K+ concentration difference across the cell membrane - Establishment of negative electrical potential inside the cell
§ The sodium-potassium pump (a membrane protein) exchanges three Na+ ions for two K+ ions.
Structure and Mechanism + + Action of Na /K ATPase
Functions of 1. 2. 3. 4. 5. + Na + -K pump It control the cell volume. It maintains Cytosolic ion concentration. It maintains Resting membrane potential. It help to synthesis of protein. It mediate action of hormone.
CALCIUM PUMP
Secondary active transport Ø In this type, transport of substances are coupled to the primary active transport Ø Usually secondary transporters utilize sodium Ex: Primary active transport of Na+ by Na+/K+ ATPase, creates sodium conc gradient across plasma membrane which indirectly stores energy for secondary active transport
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11 3 2 4
Vesicular Transport • Macromolecules that are too large move in or out of the cell with the help of bubble like vesicles created from cell membrane. • Types of Vesicular transport q Endocytosis q Exocytosis
ENDOCYTOSIS It is the case when a molecule causes the cell membrane to bulge inward, forming a vesicle. Types of Endocytosis PHAGOCYTOSIS: It is the type of endocytosis where an entire cell is engulfed. PINOCYTOSIS: It is when the external fluid is engulfed. RECEPTOR-MEDIATED ENDOCYTOSIS It occurs when the material to be transported binds to certain specific molecules in the membrane.
Exocytosis: Forces material out of cell in bulk Ø membrane surrounding the material fuses with cell membrane ØCell changes shape – requires energy Ex: Hormones or wastes released from cell
Transport across the epithelia There are two mechanism for transport across the epithelia q. Transcellular transport q. Paracellular transport
SUMMARY
REFERENCES 1. Comprehensive Textbook of Medical physiology (Vol 1 first edition)- G K Pal 2. Text book of medical physiology (Vol 2 6 th edition)- A K Jain.
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