Would this be a better answer? Would it be necessary to mention other parts of the alimentary canal? I
Q1. Absorption of nutrients depends on concentration differences so that substances diffuse across the absorbing surface. Explain how the concentration difference is maintained in the parts of the alimentary canal where absorption occurs.
Concentration difference is maintained in the small intestine which consists of millions of lacteals. Inside the villus is a lymph capillary, called a lacteal, which is surrounded by a network of blood capillaries.The structure of a villus is ideally suited to its function of nutrient absorption. Each villus is about 1mm long and is covered by a single layer of cells. In the small intestine there is high surface area which allows for greater absorption into either lymph or blood vessels. This is due to the folding of lacteals allowing for a larger surface area to volume ratio (SA:V) within the small intestines allowing for more efficient absorption of nutrients.
In the lacteals there is active and passive transport of materials. Monosaccharides, amino acids, water soluble vitamins undergo active transport into blood. Osmosis involves the passive transport of water into blood.Osmosis must occur through a semipermeable membrane and mainly occurs in the large intestines. Concentration difference is maintained through the constant movement of concentrations of lacteal in the villi in the small intestine. The concentration difference is also maintained by the diffusion of fat soluble vitamins and fatty acids and glycerol into lacteal. The movement for passive transport is along the concentration gradient, as well as the fact that active transport is against the concentration gradient and requires energy in the form of ATP.
Absorption is further enhanced by continual movement of the villi brought about by the muscular movements of the intestinal wall. This constantly brings the villi into contact with different parts of the intestinal contents, These contents are constantly changing as new material is emptied into the small intestine from the stomach.
I've tried to answer this question as well?
Q1. In doing the wall sit in Activity 11.2, your quadriceps muscle was contracting isometrically. Muscles are also to contract isotonically. Find out the difference between these two types of muscle contraction. Then, using the biceps muscles as an example, describe situations that would result in each of these two types of contraction.
Isometric contractions is when muscle shortens and movement occurs. Whereas, Isotonic contractions is when muscle does not shorten but tension increases.
Types of Muscle Contraction. An isotonic concentric contraction results in the muscle shortening, an isotonic eccentric contraction results in the muscle lengthening. During an isometric contraction the muscle is under tension but neither shortens, nor lengthens.
One example of a situation where these two types of contractions occur is when you lift a weight/dumbbell.
Isotonic: lifting a dumbell?
Isometric: tension(increase of workload) applied while joint and muscle remains in the same position. Eg. holding a cup and filling it with water. Eg. yoga.
I've also tried to answer this question but I'm not sure whether my assumption is right
Q3. The desert hopping mouse lives on dry seeds and never drinks water. It has extremely long kidney tubules.
From where does the desert hopping, mouse get its water? (refer to chap 6)
Even through the desert hopping mouse lives on only dry seeds the glucose it extracts from its food will inevitably produce water as a byproduct.The desert hopping mouse gets its water as a byproduct of cellular respiration by using the dry seeds it ingests as a source of energy. This enables the desert hopping mouse to get water through cellular respiration.
The equation for respiration:
C6H12O6 + 6O2 6CO2 + 6H2O
Glucose + Oxygen Carbon dioxide + water
How is the desert hopping mouse able to reduce water loss in urine to a minimum?
The desert hopping mouse can reduce water loss in urine to a minimum through its extremely long kidney tubules. These tubules will filter and absorb as much water as possible. The long kidney tubules of the desert hopping mouse is significantly more efficient when compared to human kidney tubules.
Another question:
Q4. At one time. It was believed that disease was caused by ‘bad blood’. Taking large amounts of blood from a patient by bleeding (blood-letting) was widely practised as a cure for disease. Louis XII of France had blood taken 47 times in six months; Louis XV was bled 38 times, and Charles XII of England had blood taken numerous times, even just before his death. Describe some of the effects that the removal of large quantities of blood would have on a patient.
Blood-letting was a common practise in medical history which involved the removal of some of a patient's blood for therapeutic purposes to heal ailments. Some effects of the removal of large quantities of blood on a patient include: weariness and dizziness due to anaemia, fall in blood pressure, people may be tired, short of breath, and pale. These effects occur because due to the removal of large quantities of blood, blood pressure falls because the amount of fluid left in the blood vessels is insufficient. The body’s oxygen supply is drastically reduced because the number of oxygen-carrying red blood cells has decreased so quickly.
If there is extreme blood loss the effects on the patient could be life threatening such as hypovolemic shock or Hemorrhagic Shock.