As Human Biology Essay

Place the end of another slide (the spreader) on the sample slide 3. Hold the spreader at an angle of apron ICC and push it along the slide, spreading the drop of blood into a smear. 4. Label the slide with the patient’s details and allow it to air dry, so the cells stick to the slide 5. Fix the slide using alcohol, this preserves the cells 6. Stain the slide using a Roman’s stain, e. G. Wright’s or Legman’s. The stain is poured over the slide, left for apron 2 minutes and the excess is washed off with water. Differential stain E. G. Legman’s, makes some structures appear darker or a different color.

In a blood film the nucleus of leukocytes will be stained purple, this allows interruptions, lymphocytes and monocot’s to be identified from each other by the shape of their nuclei. Hammertoe’s A special counting chamber designed for counting blood cells. It has a central platform with grooves either side of it. There is a tiny grid etched onto the platform, this looks a bit like graph paper. In the centre of the grid there are some triple lined squares, these measure exactly 0. 2 x 0. 2 mm. When you put the cover slip on top the platform is exactly 0. 1 mm below the cover slip.

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This means that when you look at en of the triple lined squares under the microscope you are looking at a volume of 0. 1 xx. 2 x 0. 2 = 0. 004 reran. If we are counting erythrocytes, the sample is diluted with Dace’s fluid; the blood is diluted 1 in 200. Each triple lined square has a volume of 0. 004 mm, the blood was diluted 200 times and we count five triple lined squares (0. 004 x 5 = 0. 02 mm). So if the number of cells counted in the five triple lined squares is E, the number of red cells in 1 mm of blood is: 1 10. 02 x E X 200 =EXIGUOUS If cells lie on top of the triple lines around the edge of the square, we apply the

NORTHWEST RULE. If a cell lies on the middle of the triple lines on the north or west of the grid, we count it; if it is lying on the south or east of the grid, we miss it out. Counting leukocytes A different dilution is used (1 in 20) and the four corner squares are used to count the cells. Types of blood cell Red blood cells (erythrocytes) • Biconcave discs, transport oxygen and some carbon dioxide. Their shape means they have a relatively large surface area to volume ratio to speed up gas exchange. Their cytoplasm is packed Witt a pigment called hemoglobin, t associates reversibly with oxygen.

Mature red blood cells have no nucleus; this gives them more room for hemoglobin. Erythrocytes are also very small and flexible so they can be flattened against capillary walls; this reduces the distance that gases have to diffuse across and speeds up gas exchange. Leukocytes (white blood cells) Interruptions • Have small granules in the cytoplasm. These cells engulf microorganisms by phagocytes. Lymphocytes • Have a large, darkly stained nucleus surrounded by a thin layer of clear cytoplasm. There are two kinds, B lymphocytes and T lymphocytes. B – produce antibodies; T- several functions including cell destruction.

Monocot’s • Largest kind of leukocyte. They have a large, bean shaped nucleus and clear cytoplasm. They spend 2 to 3 days in the circulatory system, then move into the tissues. They then become macrophages, engulfing microorganisms and other foreign material. Platelets • Fragments of giant cells called mastectomy’s. They are involved in blood clotting Calculating magnification Remember the units • 10-3 mm millimeter • 10-6 pm micrometer • 10-9 NM nanometer Magnification = Size of structure in the picture Real size of the structure Real size = Size tot structure in Magnification the picture

Always measure structures in pictures in millimeters. You can convert it into micrometers by multiplying it by 1000 (or add three zeros) The plasma membrane Cell membranes are made up of two kinds of molecules. • Phosphoric – form the bulk of the membrane • Proteins- scattered around in the membrane • Also, some molecules of carbohydrate and cholesterol may also be present. Phosphoric Made of a glycerol molecule with a phosphate group and two fatty acid chains attached. The phosphate group is hydrophilic (water loving) because it has a charge. It is soluble in water. The fatty acid chains are made of hydrocarbons.

They are hydrophobic (water hating). They have no charge and are insoluble in water. The phosphoric pack together in a membrane. They form a belayed. There is water both inside and outside the cell. The fatty acid tails (hydrophobic) pack together away from the water. The hydrophilic heads arrange themselves on the outside of the membrane, facing the water. I Membrane system I I Plasma membrane cell contents I Function I Partially permeable. Retains I I Rough endoplasmic reticulum I Ribosome synthesis proteins. Membranes package them for distribution I I larboard the cell I Synthesis of lipids including steroids

I Smooth endoplasmic reticulum I I Googol apparatus I Synthesis tot globetrotting, polysaccharides and hormones, production tot I I I lossless I I Nuclear envelope I Regulates exchange between cytoplasm and nucleus Organelles I Lossless digestion I Nucleus Contains DNA and regulates cell activity I Aerobic respiration and production of TAP I Contain enzymes for intracellular I I mitochondria I I Chloroplast I Absorbent of light energy and production of carbohydrates in I photosynthesis Comparison of plant and animal cells I organelles I Nucleus I Nucleolus I Ribosome I Cell wall I Plasma membrane

I Googol apparatus I Rough endoplasmic reticulum Smooth endoplasmic reticulum I Mitochondria I Chloroplasts I Animal cell I Yes I No leaf / green parts) I I Permanent vacuole I Cytokine’s I Plant cell I Yes (only in Water potential and diffusion Diffusion The net movement off substance from a region where it is in higher concentration too region where it is in lower concentration. This continues until the molecules are evenly distributed. This is a passive process as it does not require additional energy. Facilitated diffusion Molecules that are soluble in water or charged particles (ions), cannot diffuse wrought the phosphoric belayed.

They use proteins to help. This is called facilitated discussion. Some tot the protein channels are permanently open. Is lined with hydrophilic amino acids and water. The protein channel Molecules can also diffuse through the membrane by binding to carrier proteins. The molecule binds to the carrier protein, this causes the protein to change shape and release the molecule on the other side of the membrane. No additional energy is used so the process is passive. An example of this is glucose diffusing into red blood cells through carrier proteins. Osmosis This is a special kind of diffusion.

Water potential can be used to explain it. Water potential is the tendency of a solution to gain or lose water. Pure water has the highest possible water potential of zero. Adding solutes to water decreases its water potential – it makes it more negative. Water molecules will move by osmosis from a region of higher water potential to lower water potential across a selectively permeable membrane. This occurs until the water potential is the same on both sides – an equilibrium has been reached. Isotonic – a solution with the same water potential as a cell Hypersonic – a solution with a lower water potential than the cell

Hypotonic – a solution with a higher water potential than the cell Keeping the osmotic balance Glucose and other solutes will dissolve in blood plasma and lower the water potential, it is mainly the concentration of electrolytes in plasma and cells that is responsible for maintaining a water potential balance. Electrolytes are ions with a positive or negative charge. Positively charged ions are actions, negatively charged ions are anions. An electrolyte test measures sodium, potassium, chloride and bicarbonate ions; other plasma ions such as calcium, magnesium and phosphate can also be tested for.

The electrolyte level range is narrow, monitoring levels in hospital are essential and can indicate conditions such as tachycardia and cardiac arrest (low); raised levels, above 6. 0 mol dim-3 are associated with barricade and heart failure. Active transport The movement of a substance across a cell membrane against its concentration gradient using energy from TAP. The substance passes from an area where it is in low concentration to an area where it is higher. The substance is transported using a specific carrier protein. Most cells contain a sodium-potassium pump.

This is a carrier protein that uses A energy to transport sodium ions out of the cell and potassium ions into the cell. The plasma membrane of cells lining the kidney tubules give an example of transport mechanisms working together. E. G. Active transport pumps sodium ions out of the cell and potassium ions in; low sodium ions within the cell allows them to diffuse in bringing other ions and molecules in at the same time using the same carrier proteins; water moves in by osmosis; substances move from the cell to the capillary by diffusion.

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