6A_Gaseous+Exchanges

Muscles are red as they have myoglobin (combines with oxygen). Because when you run, you can't wait for the heart to pump oxygen from you, so you take oxygen straight from the muscle. Therefore oxygen debt (owes the myoglobin oxygen) -> panting. Sometimes, when some people run, they turn pale, as all the blood is going to the legs. May feel itchy, as blood is going to places it normally doesn't go, nerves.

Lactic acid is converted to carbon dioxide and water in the liver; deemed as a 'poisonous substance' in your body.

In blood: haemoglobin (combines with oxygen). In chicken, breast meat is less red as they have myoglobin.

If you want to kill a cockroach, just squash it. (You can't drown it). They take in air through tracheal Highly successful due to their structure.

Water weighs down your whole lungs, too much water, cannot undergo ventilation

In our lungs: tracheal -> bran? -> bran? -> aeriol(?) Air sacs: covered in a film of moisture. Dissolved in the fluid.

I breathe in oxygen? (not true). We breathe in AIR. oxygen goes into the blood stream by diffusion (less concentrated), bonds with haemoglobin. Nitrogen: doesn't bond with anything; body doesn't care for it.

divers: if they come up too soon, with out depressurizing, joints stuck (because of capillaries), capillaries in brain burst

Properties of Gas Exchange surfaces - Large surface area to volume ration Flick's law: (Surface areas x difference in concentration across the membrane) / thickness of the membrane - Thin membranes (easy to diffuse through) - Moisture (life on earth: aquatic -> land, but we never took the water out of us. Gas must be dissolved in liquid before it is captured by haemoglobin) - Efficient transport system (circulatory system -> high concentration gradient established) - A ventilation system that allows air to go in and out

The Human Respiratory System (must know all the names) - nares *air filtered - phalanx - larynx(voice box) contains vocal folds - trachea (windpipe): has to be a tube. Has cartilage, to make sure it stays solid. The cartilage is C-shaped, because the oesophagus is next to it, and when you swallow, the bolus of food can move down easily. - intercostal muscle (ribs) (allows your ribs to move forward and upwards) - lungs: - bronchioli - Alveoli sacs (at end of bronchioli): alveolus cells surrounded by capillaries: very efficient. Alveolar space: the space inside the alveoli.

Pressure is inversely proportional to volume (P = 1/v). When you pull down the bottom, the volume (thoracic cavity) will increase, and the pressure will decrease. As the pressure inside the air sac is lower than the outside pressure, then air will enter. When you push it up, the volume decreases, pressure increases, air leaves the lungs. The relaxation and concentration of the intercostal muscles and diaphragm is the one that causes air to leave and enter the lungs.

Our face has lots of chambers so that it sounds better. Also allows mucus to accumulate. Sinus problem: unable to allow your mucus to drain down.

All our muscles come in bunches, there is a membrane that wraps them together (different ones may have different strengths). At the back, your ribs are attached to the backbone (to allow you to stand up straight), in the front, attached to cartilage (the translucent white thing in chicken wings), it's elastic (can do CPR on it, won't puncture your heart, will slightly massage your heart)

Most people have 12 sets of ribs, which are connected to the sternum by cartilage. This makes them more flexible, so they can move forwards and up while breathing. The first seven pairs of ribs are directly attached to the breastbone, while the rest are attached to the sternum by a cartilage band. The last 2 pairs are not attached to the sternum or cartilage (floating ribs). The last five pairs are called false ribs.  Our body is not symmetrical: our heart is on the left, therefore our left lungs have one less lobe.

After you hyperventilate, you can hold your breath for a longer period of time.

Transport of oxygen: takes up from blood. Oxygen dissolves, 98% taken up by haemoglobin (in red blood cells). Contains 4 molecules of some iron thing, then can take up oxygen. Deoxy-haemoglobin and oxy-haemoglobin. The partial pressure of oxygen represents the level of dissolved O2. If partial pressure in the tissues is less than the partial pressure in the capillaries, then the oxygen moves towards the cell. Pressure may drop very low (eg. at high altitude) (85%?)

Transport of carbon dioxide:

- carbonic anhydrase converts the carbon dioxide into carbonic acid. (therefore the pH of our blood is always slightly acidic). Speeds up reaction 250 times. Makes it possible to transform large amounts. In the lungs, this process is reversed. Low pH: producing a lot of CO2, using a lot of oxygen, producing a lot of ATP, doing more work. A chemoreceptor in the brain, measures the pH level, sends signals to the diaphragm and intercostal muscles to relax and contract more. Therefore when you breathe into the plastic bag, the faster you're breathing. Brain is tricked into believing that you don't have enough oxygen. The mechanism for the control of breathing : the lack of oxygen or the presence of carbon dioxide (ans: CO2)

Due to your diet, your pH may be lowered, thus your body will think it does not have enough oxygen and make you breathe more, feel like you're hyperventilating all the time (some medication may make you hyperventilate, breathing shouldn't be laborious.)

Carbon monoxide has the same properties as oxygen. Will bind with haemoglobin, form a more permanent bond, will not disassociate. More and more haemoglobin will be taken up. A slow death: will fall asleep, then oxygen levels drop, die. If you find someone dying of carbon monoxide, open the windows, call ambulance. They will give them a flush of oxygen to push out the carbon monoxide.

(60% oxygen)

Usual O-level question: Describe the passage of oxygen from the atmosphere.

Elephant and mouse: who has the highest heart rate?

(can read: Abyss by Micheal?) (see Biozone)