Proper week seven - Exchange surfaces

Echange surfaces

• Lungs
• Villii
• Stomata
• Root hairs

THe lungs are located in the thorax, beneath them is the diaphragm, a sheet of stong tissue with muscles attached. THe diaphragm can only move thanks to these diaphragm muscles. WHY NOT DIAFRAM?! They are behind the ribcage. The intercostal muscles of the ribcage can contract to draw the ribs up.

Two types of breathing.

Shallow: Diaphragm muscles contract and relax ( 14 breaths per minute at rest)

Deep: Diaphragm muscles contract and relax. Intercostal muscles of the ribs also contract and draw the ribcage up and out.

Bronchi>brochiole>alveoli

Alveoli are single ceslls in contact with a rich blood supply, they are moist and facilitate diffusion.




Air in Air out

N - Nitrogen (78%) N - Nitrogen (78%)

O2 - Oxygen (21%) O2 - Oxygen (16%)

CO2 - Carbon Dioxide (0.04%) CO2 - Carbon Dioxide (4&)


Respiration is the release of energy from glucose in cells - Anaerobic of anaerobic. All living things respire (virus doesn't respire independently)

Breathing is moving air in and out of the lungs.


Root Hairs have a high surface are to absorb wate and mineral salts. THe surface area of roots and leaves has hairs to increase absorbtion of water.

Stomata (on leaves)

• Gaseous exchange
• Surface area for photosynthesis
• can open and close (fill with water)

There is more to add to this week, but it is late and I am tired. Modify later.

Links of excitement but possible dashed hopes

http://www.discoveryon.info/2009/10/master-mechanism-behind-regeneration.html

http://www.plosbiology.org/article/info%3Adoi%2F10.1371%2Fjournal.pbio.1000197

http://her.oxfordjournals.org/cgi/content/abstract/cym084v1

http://learn.genetics.utah.edu/content/begin/cells/scale/

http://imascientist.org.uk/download-science-debate-kits/

Weeeeeeeek seven

No lesson today. Here is a picture of passive face shoes.

Week 6 My exam result!

Har Har Har! 80%!

... Yes, I did get my name wrong first time, but I didn't lose points for it.

Week 6: the heart - Dissection and excercise

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

These changes increase the blood flow to the muscles and so increase the supply of sugar and oxygen and increase the rate of removal of carbon dioxide

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."

Lesson 5: The heart

We learned about the heart during the first half of the lesson. During the second half we took a test to see if we are on track and able to continue. I hope I did well, but I have sinced realised that I crossed out a correct answer and replaced it with an incorrect one. That's worse than being straight out wrong. :-(
When I have access to a scanner, I shall put some of my diagrams on the board. I may be able to tell what they are meant to represent. I may not.


The heart

• Pumps blood thru the body
• Blood flows from the heart to the organs thru arteries and returns thru veins
• In the organs, blood flows thru capilaries (veins and arteries are too think to allow anything thru)
• Substances needed by cells in the body tissues pass out of the blood, and substances pruduced by the cells pass into the blood thru the walls of the capillaries

There are two separate circulation systems, one to the lungs and one to all the other organs of the body. Lungs are the start and end of the circulation, the heart is the booster in the circuit.


Out of the heart = Arteries
Into the hear = Veins


Blood plasma transports

• Carbon dioxide from the organs to the lungs
• soluble products of digestion from the small intestine to other organs

Blood
Red blood cells transport oxygen from the lungs to the organs.
Red blood cells have no nucleus, they are packed with a red pigment called Haemoglobin.
In the lungs, haemoglobin combines with oxygen to form Oxyhaemoglobin
In other organs it splits into haemoglobin and oxygen


Present in blood are:

• Red blood cells
• White blood cells
• Plasma
• Platelets

Plasma contains
Nutrients
hormones
water
carbon dioxide
urea


Red blood cells carry haemo globin, which combines with oxygen in the lungs to form oxyhaemoglobin. Cells of all the organs want this.

Week 4: Enzymes

Enzymes are proteins, composed of amino acids. They speed up chemical reactions in cells, but remain unchanged. A catalyst.

Two types of chemical reactions that may occur:

Anabolic - Building up: Protein Synthesis, Photosynthesis
Catabolic - Breaking down: Respiration

Enzyme processes inside cells are called Intracellular. Enzyme processes outside of cells are called extracellular.


Enzymes have an optimum temperature at which they work, beyond which they function less well, or break completely. Enzymes that have been heated up too much are said te be 'de-natured' and they cannot be used again.


Here are some locations in the body and the enzymes that work there.

Mouth: Amylase

Stomach: Protease

Pancreas: Amylase, Protease, Lipase

Small intestine: Amylase, Protease, lipase


Here is what those particular enzymes do

Amylase > Starch to sugars

Protease > Proteins to amino acids

Lipase > fats to glycerol


Catalase is the fastest known enzyme. It converts hydrogen peroxide to water and oxygen.



Test, Fast Froth.

1. Cut two pieces of liver (from a lamb) to the same size
2. Put 1 into a boiling tube containing 5cm3 of hydrogen peroxide
3. Use a ruler to measure the highest point of the resulting froth and the time it took to reach that point.
4. Do the same with the second piece of liver, but this time cut it into small pieces

Which test causes froth to rise the quickest, highest? Why?
Where is the enzyme found in this test? Was the enzyme a breaker or a builder, a catabolic or an anabolic?


Recap with bullets

Enzymes

• Are proteins
• Made of Amino Acids
• Biological Catalyst - Speeds up reaction, remains unchanged
• Will be damaged at too high a temperature, or the wrong ph - De-natured
• Can be used again and again
• Human enzymes tend to work best at 37 degrees
• Fulfill one specific role - reaction or process
• Anabolic process builds
• Catabolic process breaks down

Enzymes in metabolism

• Intracellular -eg photosynthesis
• Extracellular - eg digestion
• anabolic - Protein synthesis, photosynthesis
• Catabolic - respiration

So, Photosynthesis is an intracellular anabolic enzyme process.

Week 3: Nutrition

Food, yum. Tasty and useful for it is made of:

Proteins, Carbohydrates, Fats, Vitamins, Minerals and Water. Food= Energy Energy is measured in Joules or Calories.

Energy is needed for:

Activities
Growth
Repair

Chemical reactions+Metabolism=Metabolic rate - Migh metabolic rate= High rate of reactions

Too much unused energy can lead to Obesity, which can lead to Heart Disease, High Blood pressure, Diabetes, Arthritis.

Too little energy can lead to Malnourishment - Deficiency diseases, reduced resistence to infection and irregular periods.

Nutrients in foods if not in balance can cause harm.
Too much saturated fat
Increases cholesterol, can lead to heart and blood vessel disease.
High Density Lipids is good cholesterol (will reduce plaque formation) Low Density Lipids is bad cholesterol (leads to the formation of plaques). THe balance of LDL-HDL is important and determined by diet and inherited factors. Eating poly and monounsaturated fats can reduce cholesterol.

Too much salt
Can lead to an increase of blood pressure in 30% of population. Processed foods tend to be high in salt and fat.