All living cells have cell membranes If you build a strong, safe house but don’t have any way for fresh air, food, water and energy to come in/trash, sewage to leave, house isn’t much good Put windows, doors, plumbing, electricity in house to make it Phospholipids can move sideways in membrane, Allows cells to be pliable
Many proteins span membrane – we’ll see how these can allow substances to cross membrane Glycoproteins – ABO blood types
(in the cell it’s the membrane) Raincoat impermeable, cotton jacket little use in rain – gets soaked (permeable); borders of a country – want them to be semipermeable (we decide who/what comes and goes)
Water goes through freely, small uncharged molecules like glycerol, ethanol: small hydrophobic molecules like oxygen, carbon dioxide Macromolecules too large to pass through, charged particles (ions like H+, Na, Cl, Ca) repelled by hydrophobic tails of phospholipids
Small uncharged mlcls dissolve in membrane’s lipid environment
Skateboard figure from book
Demo – room spray, food coloring in water 1. 2 drops yellow + 2 drops blue in cold 2. 2 drops yellow + 2 drops blue in hot 3. 4 drops yellow + 4 drops blue
Figure 4.5 Enger cytoplasm considered solution of salts
One example is the diffusion of oxygen through the membranes of lung cells. Carbon dioxide also diffuses from tissues where it is found in high concentration to blood and carried to lungs.
Most short-distance transport of materials into & out of cells occurs by diffusion
Water molecules can easily diffuse through cell membranes. Water follows salt. Important because it allows water to be reabsorbed in the kidney and large intestine.
Osmotic pressure is the hydrostatic pressure produced by a difference in concentration between solutions on the two sides of a surface such as a semipermeable membrane . When a biological cell is in a hypotonic environment, the cell interior accumulates water , water flows across the cell membrane into the cell, causing it to expand. In plant cells , the cell wall restricts the expansion, resulting in pressure on the cell wall from within called turgor pressure . Turgor is a force exerted outward on a plant cell wall by the H2O contained in the cell. This force gives the plant rigidity, and may help to keep it erect. Turgor may also result in the bursting of a cell.
Comparing hyper, hypo, isotonic solutions Different blood cells
When we did cell lab, what happened to elodea cells?
Pump out water (contractile vacuoles) – unicellular organisms Saltwater organisms pump out salts Plants protected by cell wall http:// www.amnh.org/exhibitions/water/?s ... Surviving in Saltwater No matter how thirsty you are, drinking seawater will only make you thirstier. Seawater is too salty for humans and most land animals—it's about 3.5 percent salt by weight. Seawater dehydrates you because the amount of water needed to flush the excess salt from your body would be more than what you drank. But many animals that live in or near the ocean have evolved ways to pump out the extra salt while keeping their water levels in balance. Secreting Salt A wandering albatross spends months at a time flying or floating on the open ocean, far from any source of fresh water. So albatrosses have evolved a way to drink seawater, which is too salty for most birds and land animals. To get rid of excess salt from the water and food they ingest, albatrosses have salt glands just behind their eye sockets. The glands excrete a highly concentrated salt solution that drains out through the tip of the beak. Soaking in Salt Most fish that live in the ocean tend to lose water-the high salt content of the ocean causes water to constantly flow out through the fish's gills. So fish need to drink lots of seawater to stay hydrated. And because seawater is so salty, they also must pump out the excess salt, both through their kidneys and using specialized cells in their gills. Bony Saltwater Fish 1. WATER naturally seeks a chemical balance, or equilibrium. That means water flows from areas of higher water concentration to areas of lower water concentration to equalize the system. WATER concentration inside a fish is higher than in the ocean itself because the ocean is so SALTY. As a result, most saltwater fish constantly lose WATER through their gills and skin. 2. Because the fish is losing WATER, it must drink a lot to stay hydrated-but SALTY seawater is the only water around. 3. To get rid of excess SALT, the fish's kidneys pump lots of salt into its urine. Sharks 1. Sharks don't lose WATER the way bony fish do-their bodies stay in balance with the ocean in a different way, thanks to the chemical called urea. There's essentially as much UREA and other chemicals in water inside a shark as there is SALT in seawater. So the shark stays in balance with the saltwater outside its body and water doesn't constantly flow out. 2. Instead of drinking WATER, the shark absorbs some seawater (and SALT) through its gills. 3. A gland in the shark's digestive system gets rid of excess SALT. In Balance with the Ocean All the salt in the ocean can make life complicated for animals living there. Sharks cope with the salty water by generating lots of the chemical urea. This substance, produced throughout the shark's body, counterbalances the salt in the ocean water. In other words, there's as much salt in the seawater as there is urea (and other chemicals) in the water inside the shark's tissues . So sharks don't lose water the way fish do. The shark gets rid of excess salt using a salt-excreting gland near its anus.
Water channels are called aquaporins. Discovered in the 1990’s. Discoverer received Nobel Prize in 2003. http://www.hopkinsmedicine.org/press/200...
ATP is energy-carrying molecule in cells
Some molecules move into cells by endocytosis and out by exocytosis. Endocytosis – cells take in substances by vesicle formation as plasma membrane pinches off.
If time, go outside. Bring a bucket of water and some batteries. Make a cell by holding hands. Make a vesicle. Do endo and exo cytosis using energy from baatteries.
Seen how different types of transport across membranes allow cells to control what comes in and out of them (ions, nutrients, Water, wastes)
Waste products include excess salts, CO2, nitrogenous wastes from metabolism of proteins and nucleic acids For next few days, we’ll talk about how multicellular organisms maintain homeostasis (steady state) in the areas of gas exchange and waste removal.
Energy for metabolism, transport, movement, etc…
Photo: http://www.waterlife.co.uk/seaquariums/coralfish2.htm Oxygen concentrations are much higher in air, which is about 21% oxygen, than in water, which is a tiny fraction of 1 percent oxygen. Where the air and water meet, this tremendous difference in concentration causes oxygen molecules in the air to dissolve into the water. More oxygen dissolves into water when wind stirs the water; as the waves create more surface area, more diffusion can occur. A similar process happens when you add sugar to a cup of coffee - the sugar dissolves. It dissolves more quickly, however, when you stir the coffee. Another physical process that affects DO concentrations is the relationship between water temperature and gas saturation . Cold water can hold more of any gas, in this case oxygen, than warmer water. As dissolved oxygen levels in water drop below 5.0 mg/l, aquatic life is put under stress. The lower the concentration, the greater the stress. Oxygen levels that remain below 1-2 mg/l for a few hours can result in large fish kills.
[O2] (21%) and low [CO2] (0.03%) compared to tissues
Air is filtered, warmed and humidified before reaching lungs http://images.search.yahoo.com/images/view?back=http%3A%2F%2Fimages.search.yahoo.com%2Fsearch%2Fimages%3F_adv_prop%3Dimage%26fr%3Db1ie7%26va%3Dbreathing%26sz%3Dall&w=348&h=295&imgurl=www.people.eku.edu%2Fritchisong%2Fbreathingmechanics.gif&rurl=http%3A%2F%2Fwww.people.eku.edu%2Fritchisong%2F301notes6.htm&size=9.8kB&name=breathingmechanics.gif&p=breathing&type=gif&oid=d116cb534bb1a9b8&no=1&tt=298,236&sigr=11ig4pj62&sigi=11kllrfpv&sigb=12pvbbgvb
Anatomy. A thin-walled, cartilaginous tube descending from the larynx to the bronchi and carrying air to the lungs. Also called windpipe . Bronchus – bronchiloes get smaller and smaller and lead to alveoli
There are about 600 million alveoli in your lungs and if you stretched them out, they would cover an entire tennis court. Each lung has millions (3) of alveoli with thin walls, supplied with many capillaries Breathe by negative pressure. The air that leaves a person's lungs during exhalation contains 14% oxygen and 4.4% carbon dioxide. mistupid.com/chemistry/ air comp.htm The air’s oxygen content was 35% during this period, compared to the 20% we breathe now,
Asthma is a chronic disease that affects your airways. Your airways are tubes that carry air in and out of your lungs. If you have asthma, the inside walls of your airways become sore and swollen. That makes them very sensitive, and they may react strongly to things that you are allergic to or find irritating. When your airways react, they get narrower and your lungs get less air. This can cause wheezing, coughing, chest tightness and trouble breathing, especially early in the morning or at night. http://www.nlm.nih.gov/medlineplus/asthma.html When your asthma symptoms become worse than usual, it's called an asthma attack. In a severe asthma attack, the airways can close so much that your vital organs do not get enough oxygen. People can die from severe asthma attacks. Asthma is treated with two kinds of medicines: quick-relief medicines to stop asthma symptoms and long-term control medicines to prevent symptoms. http://www.geekland.org/picture_library/asthma_worm.jpg (2 nd photo)
Asthma is a chronic condition involving the respiratory system in which the airways occasionally constrict, become inflamed , and are lined with excessive amounts of mucus , often in response to one or more triggers. [1] These episodes may be triggered by such things as exposure to an environmental stimulant such as an allergen , environmental tobacco smoke, cold or warm air, perfume, pet dander, moist air, exercise or exertion, or emotional stress . In children, the most common triggers are viral illnesses such as those that cause the common cold . [2] This airway narrowing causes symptoms such as wheezing , shortness of breath , chest tightness, and coughing . The airway constriction responds to bronchodilators . Between episodes, most patients feel well but can have mild symptoms and they may remain short of breath after exercise for longer periods of time than the unaffected individual. The symptoms of asthma, which can range from mild to life threatening, can usually be controlled with a combination of drugs and environmental changes.
Protozoa and small multicellular animals (e.g. platyhelminthes) without involvement of circulatory systems. Involves simple diffusion across moist membrane into cells. Annelids (Oligochaeta - earthworm) with simple integument (skin) with capillary beds underneath for gas exchange. Animals with complex ‘external’ integument (e.g. external gills - salamandar; internal gills - fish; parapodia - Polychaeta) and capillary beds. Complex internal integument without circulatory system involvement (e.g. trachea of insects) (see fig. 41.5). Complex internal integument with circulatory system involvement (e.g. vertebrate lungs).
Orgs need a way to quickly and reliably remove ammonia from cells
Clean house by taking everything out and bringing back only what you want
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