topic 6 essay q's

Question 1

What is the role of Amylase in digestion?

Answer 1

1. Amylase is an enzyme
2. secreted by salivary glands/pancreas
3. acts on starch/polysaccharides
4. breaks glycosidic bonds by hydrolosis
5. product is maltose/disaccharide/sugar molecule

Question 2

What are the processes involved in absorbing different nutrients across the cell membrane of villus epithelium cells lining the small intestine?

Answer 2

1. simple diffusion of nutrients along a concentration gradient (fatty acids)
2. facilitated diffusion of nutrients involves movement through channel proteins (fructose)
3. active transport of nutrients against concentration gradient involving protien pumps (iron ions, glucose, amino acids)
4. endocytosis by means of vesicles (cholesterol in lipoprotien particles)

Question 3

What are the digestive system components?

Answer 3

• mouth
• esophogus
• stomach
• pancreas
• gall bladder
• small intestine
• large intestine
• anus

Question 4

How does the small intestine move, digest, and absorb food?

Answer 4

1. peristalsis helps to move food along
2. peristalsis/muscle contractions mix food with intestinal enzymes
3. enzymes digest macromolecules into monomers
4. pancreatic enzymes: amylase, lipase, endidopeptidase chemically digest food in lumen.
5. amylase digests starch
6. bile is secreated into the small intestines to create a favorable pH for the enzymes
7. mucosa layer contains villy, fingerlike projections on the innerlining of the small intestine
8. villi increase surface area for better absorption and absorb the products of digestion

Question 5

How does leptin control appetite?

Answer 5

1. leptin suppresses/inhibits appetite
2. secreted by adipose tissue
3. level is controlled by the amount of adipose tissue (fatty tissue)
4. leptin targets cells in hypothalemous of the brain
5. causes hypothelemus to inhibit appetite

Question 6

How are materials exchanged between capillaries and tissues?

Answer 6

1. molecules move by diffusion/move down a concentration gradient
2. nutrients move into tissues
3. gas exchange/oxygen and carbon dioxide change between tissues and blood cappillaries
4. hormones leave cappillaries in target tissues to attach to receptors on cells

Question 7

What are the structures and functions of arteries and veins?

Answer 7

1. both have 3 layers in their walls
2. pressure is high in arteries and low in veins
3. arteries receive blood from ventricles and carry blood away from the heart
4. lumen of artery is narrow to keep the pressure high
5. muscle/elastic fibers help to maintain pressure between heartbeats
6. veins recieve blood from cappillaries and carry blood to the heart
7. large lumen so less resistance for blood flow
8. valves in veins prevent blood flow

Question 8

What happens in the alveoli?

Answer 8

1. gas exchange
2. oxygen diffuses from air to blood and carbon dioxide diffuses from blood to air
3. oxygen binds to haemoglobin in red blood cells
4. pressure inside and volume of alveoli increases and decreases during inspiration, expiration and ventilation
5. blood flows through capillaries so the concentration gradient of oxygen and carbon dioxide is maintained
6. type ii pneumocytes secrete surfactant to prevent sides of alveoli adhering

Question 9

How does a nerve message pass from one neuron to another?

Answer 9

1. nerve impulses reach the end of the presynaptic neuron
2. depolarization causes calcium channels in membrane to open
3. calcium diffuses into the presynaptic neuron
4. vesicles containing neurotransmitter move and fuse with presynaptic membrane
5. neurotransmitter released by exocytosis into synaptic cleft
   - diffuses across the synapse
   - ttaches to receptors on postsynaptic neuron
6. receptors cause ion channels to open and sodium diffuses into postsynaptic neuron
7. postsynaptic neuron is depolarized
   - causes new action potential
   - neurotransmitter is broken down
   - then reabsorbed into presynaptic neuron

Question 10

What controls the blood glucose levels and what are the consequences if they are not maintained?

Answer 10

1. homeostasis is the maintenance of constant internal environment
2. pancreas produces hormones that control the level of blood glucose
3. if glucose concentrations are high beta cells in the pancreas will secrete insulin
4. insulin causes cells to absorb glucose
5. liver stores excess glucose as glycogen.
6. if glucose concentrations are too low alpha cells in the pancreas produce glucagon
7. glucagon causes the liver to break down glycogen into glucose
8. if pancreas produces little/no insulin the person can develop type 1 diabetes
9. type 11 diabetes is when a person becomes resistant to insulin