Here are some pictures of a sheep's heart that I dissected.
1.This is a sheep's heart. It is not complete, only the lower ventricles remain. Also shown is a pair of sharp scissors that I used to cut it with. See it here Here is a closeup. See it here.
You can see the stumpy remains of the Vena Cava and the Pulmonary vein. Pulmonary is probably latin for lungs. Had the butcher left the organ whole, there would have been the Pulmonary Artery and the Aorta. There would also have been the left and right aorta. Both of those are thick tubes. They have to be thick to contain the high pressures that they are exposed to. Blood exits the heart thru the ARTERIES. Blood re-enters the heart thru veins. Arteris branch and narrow until they become capillaries. Capillaries have thin walls.
Substances needed by cells in the body tissues pass out of the blood, and substances produced by the cells pass into the blood through the walls of the caplillaries.
2. The first cut. See it here.
Clearly one ventricle has a thicker wall than the other. The left ventricle is strong. After welcoming the oxyhaemoglobin from the lungs, it then has to propell the blood all the way around the body, visiting all of the organs.
3. The second cut. See it here.
What's that between the left ventricle and atrium? Its a mitral valve. Its stops blood going the wrong way.
There is a similar one between the right ventricle and atrium called the tricuspid valve
Excercise
- Increases heart rate
- increases breathing rate in response to greater co2 - need for more 02
- all blood vessels to muscles dilate (more blood > more oxygen > greater capacity to expell co2 and lactic acid.)
- Increases respiration rate
- ^accumulation of lactic acid
Respiration happens in the cells. It is the increased presence of carbon dioxide that initiates increase in breating rate.
Respiration (aerobic)
Glucose + oxygen > Carbon dioxide + water + Energy
Respiration (anaerobic, no 02)
Glucose is broken down without oxygen > lactic acid + energy.
Lactic acid must be taken away, it is a toxin. Lactic acid is taken to the liver to be oxidised. Until this has happened, it is said there is an oxygen dept.
THere is a store of glucose in the muscles for use in respiration. Glycogen. Glycogen = lots of glucose molecules. Anaerobic respiration begins after 5 seconds of intense activity
During excercise
- Heat rate increases - increase o2 thru the lungs and carries out co2
- Increase breathing rate - Co2 out, O2 in.
- Arteries supplying the muscles dilate
- Blood flow which aids digestion lowers - Blood supply varies
The energy that is released during respiration is used to enable muscles to contract.
During excersice a number of changes take place
- Heart rate increases
- Rate and depth of breathing increases
- the arteries supplying the muscles dilate
Glycogen stores in the muscles are used during excercise.
If muscles are subjected to long periods of vigourous activity they become fatigued, ie, they stop contracting efficiently. If insuuifient oxygen is reaching the muscles they use anaerobic respiration to obtain energy.
Anaerobic respiration is the incomplete breakdown of glucose and produces lactic acid. As the breakdown of glucose is incomplete, much less energy is released than during aerobic respiration. Anaerobic respiration results in oxygen debt that must be repaid in order to oxidize lactic acid to carbon dioxide and water.
"i wish i was a helicase enzyme, because i'd love to unzip your genes..."
"Went to the shop to buy a bottle of energy. 'That'll be ATP' said the shopkeeper."
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