Cell Membranes
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The document summarizes the fluid-mosaic model of cell membranes. It describes how phospholipids spontaneously organize to form bilayers in water due to their amphipathic structure. Proteins and cholesterol are embedded in the phospholipid bilayer, allowing it to be fluid. This structure allows the membrane to regulate what enters and exits the cell while maintaining its fluidity.
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Cell Membrane
The document summarizes key aspects of the cell membrane. It discusses how the cell membrane is made of phospholipids and proteins arranged in a fluid mosaic structure. It selectively controls what passes in and out of cells through diffusion, channels, and pumps that may require energy. Water movement across the membrane occurs through osmosis, with cell regulation to prevent bursting or shrinking due to gaining or losing too much water from their surroundings.
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The cell membrane separates cells from their surroundings and controls what passes in and out. It is a phospholipid bilayer with embedded proteins. Water and some small molecules can pass through the membrane directly via diffusion. Larger molecules and ions require membrane protein channels or pumps to cross. Cells use both passive transport like facilitated diffusion and active transport like pumping to regulate movement across the membrane and maintain homeostasis.
The cell membrane - A micro-insight of life.
The cell membrane separates the living cell from its non-living surroundings. It is selectively permeable and controls what enters and exits the cell. The membrane is made of a phospholipid bilayer with proteins and other molecules embedded within it. Water and some small molecules can pass through the membrane via simple diffusion or facilitated diffusion through protein channels. Larger molecules and ions require active transport using membrane proteins that use energy from ATP. The movement of water into and out of cells, called osmosis, depends on the concentration of solutes on either side of the membrane and works to maintain the cell's water balance.
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The document summarizes key concepts about cell membranes and movement of materials across membranes. It discusses how cell membranes are made of phospholipid bilayers with embedded protein channels. Materials like water and small molecules can pass through the membrane directly via simple diffusion down their concentration gradient. Larger molecules and ions require protein channels to cross via facilitated diffusion. Active transport uses energy to pump molecules against their gradient. The document also explains how water moves across membranes via osmosis, down its concentration gradient, and how cells regulate water movement to maintain homeostasis in different environments.
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The cell membrane controls what enters and exits the cell. It is made up of a phospholipid bilayer with proteins embedded. Phospholipids have hydrophobic fatty acid tails and hydrophilic phosphate heads, arranging in a bilayer. Proteins allow selective permeability and perform functions like transport. Movement across the membrane includes passive diffusion, facilitated diffusion through protein channels, and active transport using protein pumps and ATP. Water moves across by osmosis, from high to low concentration areas. Cells regulate water balance in different conditions like hypotonic, hypertonic, and isotonic environments.
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The cell membrane separates the living cell from its non-living surroundings. It is a thin barrier made of phospholipids, proteins, and other macromolecules arranged in a fluid bilayer. This structure allows the membrane to be selectively permeable, controlling what moves in and out of the cell. Substances can cross the membrane through diffusion, facilitated diffusion using membrane protein channels, or active transport against the concentration gradient using protein pumps that require ATP. Water also crosses the membrane through osmosis, moving from areas of high water concentration to low concentration.
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Membranes
Membranes are composed of lipids and proteins arranged in a fluid bilayer. This structure allows membranes to compartmentalize cells and carry out functions like transport. Lipids include phospholipids that form the bilayer, with hydrophobic tails facing inward and hydrophilic heads outward. Proteins embedded in the bilayer perform roles like transporting molecules across membranes. Membranes use both passive diffusion and active transport to regulate what passes in and out. Water also crosses membranes through osmosis, regulated in cells by aquaporin channels. Membranes are dynamic structures that allow compartmentalization while maintaining functions through protein and lipid movement.
thefluidmosaicmodelofmembranestructure-120322041206-phpapp01.pdf
The fluid mosaic model describes cell membrane structure. Membranes are composed of a phospholipid bilayer with proteins embedded. Phospholipids form a double layer with hydrophobic tails pointed inward and hydrophilic heads outward. This structure acts as a selective barrier. Proteins have various roles like transporting molecules, acting as enzymes, or binding receptors. The fluid mosaic model explains membranes as a fluid structure with proteins and lipids able to move freely within the bilayer.
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This document discusses episiotomy, which is an incision made in the perineum during childbirth to widen the vaginal opening. It can help prevent tearing and complications. The two main types are median and mediolateral episiotomies. Median episiotomies involve a midline incision while mediolateral incisions extend laterally towards the ischial tuberosity. Episiotomies are usually performed when the vaginal opening is distended during crowning to prevent stretching injuries. They are sutured closed after delivery.
Caesarean section
The document discusses Caesarean section, including indications, types, procedure, complications, and mode of delivery in subsequent pregnancies. A Caesarean section is a surgical procedure to deliver one or more babies through incisions in the abdomen and uterus. The rate of Caesarean sections has increased from 5% in 1970 to 25% in 1990 due to factors such as abandoning difficult procedures in favor of C-sections and increased use for breech births. Complications can include hemorrhage, infections, and injuries to the mother or baby.
Normal labour
Normal labour involves the spontaneous expulsion of a single, mature fetus through the birth canal within 3-18 hours without complications. It occurs when hormonal and mechanical factors cause the cervix to efface and dilate in stages from 3cm to full 10cm dilation. Labour proceeds through four stages: 1) cervical dilation, 2) expulsion of the fetus, 3) expulsion of the placenta, and 4) recovery. The fetus descends through the birth canal with increased flexion to facilitate delivery of the head.
Anatomy of the foetal skull
The fetal skull consists of three parts: the vault, face, and base. The vault is made up of the frontal, parietal, and occipital bones which are separated by sutures. The face extends from the chin to the nose. Fontanelles are soft spots located where sutures meet which are important for assessing fetal position and flexion. The skull has various longitudinal and transverse diameters used to determine which will engage and pass through the birth canal during delivery.
Anatomy of the female pelvis
The female pelvis is divided into the false pelvis and true pelvis. The true pelvis is further divided into the pelvic inlet, cavity, and outlet. The document describes the boundaries and diameters of each region including the anatomical transverse diameter of 13cm at the inlet. It also discusses the pelvic planes and axes, and the Caldwell-Moloy classification of pelvic types including the gynaecoid, anthropoid, android, and platypelloid pelvis.
Active management of normal labour
This document outlines the active management of normal labour in 4 stages: antenatal preparation, first stage (history, exam, procedures), second stage (delivery of baby), third stage (delivery of placenta), and fourth stage (postpartum care of mother and baby). The goal is a healthy delivery with minimal effects. Key procedures include monitoring contractions/fetal heart with a partogram, positioning, nutrition, analgesia, perineal support, and immediate newborn care.
Thyrotoxicosis in pregnancy
Thyrotoxicosis in pregnancy can cause complications like abortion and preterm labour. Clinical features include weight loss, heat intolerance, tremors, and fast heart rate. It is treated with antithyroid drugs like propylthiouracil or carbimazole. Epilepsy in pregnancy commonly presents as grand mal seizures, which are treated with phenobarbitone or phenytoin along with folic acid. Rhesus isoimmunization occurs when an Rh-negative mother develops antibodies against Rh-positive blood from her baby. It can be prevented by giving the mother anti-D immunoglobulin after delivery or pregnancy events involving blood transfer from baby to mother. Affected babies may require monitoring, phot
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Cell Membranes
- 3. PHOSPHOLIPIDS: The “Backbone” of the Membrane Cartoon of a phospholipid molecule This cartoon depicts the basic amphipathic* structure common to all phospholipids * both polar and non-polar regions Fatty acids Glycerol plus polar side group www.freelivedoctor.com
- 5. Water is a good solvent for polar molecules and ions - + - + - + - + - + Hydration Shells - + - + - + - + - + - + - + - + - + - + - + - + - + - + - + www.freelivedoctor.com Na + Cl - - + - + - + - + - + - +
- 7. OIL/WATER PARTITION: THE “KITCHEN” EXPERIMENT MIX OIL WATER AND TEST SUBSTANCE WATER CONCENTRATION OF TEST SUBSTANCE IN OIL/ CONCENTRATION OF TEST SUBSTANCE IN WATER = OIL WATER PARTITION COEFFICIENT (OWPC=K) K > 1 HYDROPHOBIC (NON-POLAR) K < 1 HYDROPHILIC (POLAR) www.freelivedoctor.com WAIT OIL
- 8. MIXING PHOSPHOLIPIDS AND WATER: Spontaneous Self-Organization www.freelivedoctor.com
- 9. MIXING PHOSPHOLIPIDS AND WATER: Spontaneous Self-Organization www.freelivedoctor.com
- 10. MIXING PHOSPHOLIPIDS AND WATER: Spontaneous Self-Organization Click ahead www.freelivedoctor.com
- 11. MIXING PHOSPHOLIPIDS AND WATER: Spontaneous Self-Organization www.freelivedoctor.com
- 16. Permeability of the BLM mol/sec-sq. cm. www.freelivedoctor.com
- 18. The membrane is fluid www.freelivedoctor.com
- 19. The membrane is fluid www.freelivedoctor.com
- 20. The membrane is fluid www.freelivedoctor.com
- 21. The membrane is fluid www.freelivedoctor.com
- 22. Cholesterol sits between fatty tails www.freelivedoctor.com
- 23. Proteins can span the bilayer Hydrophilic Hydrophobic www.freelivedoctor.com
- 25. The fluid-mosaic model www.freelivedoctor.com
- 26. Channels and carriers are needed to get ions across the bilayer www.freelivedoctor.com
- 27. Channels and carriers are needed to get ions across the bilayer www.freelivedoctor.com
- 29. An Epithelial Membrane in Cartoon Form: www.freelivedoctor.com
- 30. A Network Model of Coupled Salt and Volume Flow Through an Epithelium AM TJ BM BL CL PL CB PB CELL LUMEN BLOOD www.freelivedoctor.com