Bio f4 chap 10

Question 1

Why insects need one separate system (the tracheal system) to transport oxygen?

Answer 1

• the open circulatory system in insects is unable to distribute oxygen to all body cells
• need a tracheal system to transport oxygen to support active activities

Question 2

Why some individuals feel nauseous and faint immediately after donating blood? Why do some blood donors need to take iron pills?

Answer 2

• reduction of blood especially in the brain may cause nausea and faint spells
• help maintain healthy iron levels

Question 3

Why a person who stands too long may faint?

Answer 3

• the blood flow back to the heart requires the contraction of skeletal muscles around the veins
• if someone stands on his feet for too long, less oxygen flows to the brain
• less oxygen and glucose are transported to the brain
• causes the individual to pass out

Question 4

In what circumstances would fingers turn pale?

Answer 4

• when the blood flow is obstructed from flowing to the fingertips or when the blood vessels contract due to coldness

Question 5

Explain why the formation of blood clots in the blood vessel can cause a heart attack.

Answer 5

• if the blood clot is formed in the coronary artery, the cardiac muscles may die or suffer permanent damage due to the lack of oxygen supply
• lead to heart attack

Question 6

In your opinion, what are the factors that contribute to an individual’s risk of getting cardiovascular disease?

Answer 6

• a diet rich in lipids and low in fibre
• lack of exercise
• obesity
• smoking

Question 7

After eating fatty food, the number of lipid molecules in the lymph increases by 1%. Explain why.

Answer 7

• fatty acids and glycerol diffuse into the lacteals in the villi of small intestines
• these simple molecules then form a part of lymphatic components that are transported to the lymphatic vessel through the lacteal
• the number of lipids molecules in the lymph increases after a fat-rich meal intake

Question 8

Explain what would happen when the tissue fluid fails to return to the blood circulatory system.

Answer 8

• if excess fluid is not returned to the bloodstream, body tissues become swollen due to excessive fluid accumulated in the interstitial spaces

Question 9

Predict what would happen to the legs of a patient who has been bedridden for a long period of time? Explain your answer.

Answer 9

• may suffer from oedema due to the accumulation of tissue fluid in interstitial spaces
• the return of tissue fluid to the bloodstream requires he contraction of the skeletal muscles and muscles on the lymphatic vessel wall

Question 10

Lipid droplets or fat globules cannot diffuse into the villus blood capillary but must diffuse through the lacteal. Explain why.

Answer 10

• lipid globules are too large to diffuse into the blood capillaries
• able to diffuse through the small opening between the epithelial cells of lymphatic capillaries
• unlike blood capillaries, the epithelial cells forming the walls of lymphatic capillaries are not continuous end to end
• the ends of the lymphatic capillary cells overlap and can open like a one-way door to allow the diffusion of tissue fluid

Question 11

An individual has a low number of erythrocytes . Explain the effect of this situation on his/her health. Suggest the types of food that should be consumed by the individual to recover from this situation.

Answer 11

• low number of erythrocytes means that there are less haemoglobin to combine with oxygen to form oxyhaemoglobin
• less oxygen is transported to body tissues for cellular respiration
• less energy is produced
• becomes easily exhausted and looks pale
• may have anaemia
• consume a lot of ferum-rich foods such as spinach

Question 12

The human heart has a pacemaker. The heart pacemaker that is damaged can be replaced by an electronic pacemaker. Explain how the electronic pacemaker functions.

Answer 12

• functions as a sinoatrial node that triggers the impulse to control and maintain heartbeat
• generated electric impulse spreads to both atria and subsequently reaches the atrioventricular node
• the atrioventricular node transmits the rhythmic electric impulse throughout the ventricle and causing the heart to beat and pump blood

Question 13

Name one example of nutrient found in blood and how the nutrient can be transported to cells.

Answer 13

• glucose
• heart pumps blood from the artery to blood capillaries
• arterial diameter is larger than the capillaries
• produces a high hydrostatic pressure that forces glucose to diffuse from the blood capillaries into the interstitial spaces to form tissue fluid
• glucose concentration in the fluid is higher than that of the cells
• glucose diffuses into the cells via facilitated diffusion

Question 14

Why does the blood flow in fish encounter more obstacles compared to the blood flow in humans and explain how the fish can overcome this problem?

Answer 14

• in fishes, the blood needs to be circulated through two capillary systems (gill capillaries and systemic capillaries) before returning to the heart
• the blood flow through the capillaries poses resistance to the flow
• blood hydrostatic pressure against the capillary walls is reduced
• the oxygenated blood that leaves the gill capillaries flows at a slow rate
• in humans, blood flows in large vessels (arteries and venules) and ending with capillaries
• the reduction of blood pressure occurs gradually and the flow of blood faces less resistance
• fishes overcome this resistance by having sinus venosus, a large lumen replacing veins
• the larger size of sinus compared to veins impose less resistance to blood flow

Question 15

How smoking, unbalanced diet and unhealthy lifestyle can contribute to coronary heart disease?

Answer 15

Smoking
* contains nicotine
* causes addiction
* Nicotine shrinks blood vessels.
* Nicotine increases blood pressure.
* Causes accumulation of plaque.
* Causes thrombosis/arteriosclerosis.
* Cigarette smoke contains carbon monoxide.
* Carbon monoxide competes with oxygen to combine with haemoglobin to form carboxyhaemoglobin.
* Affects oxygen transport efficiency
* Causes difficulty in breathing and heart attack
* Cigarette smoke contains tar that forms a film on the alveoli wall which reduces gaseous exchange

Imbalanced diet
* High intake of fats/lipid/carbohydrates
* Cholesterol and fats accumulate and are deposited in the lumen of blood vessels.
* The lumen of the coronary artery becomes small and narrow.
* This can cause atherosclerosis, stroke or thrombosis.

Unhealthy lifestyle
* Lack of physical exercise and a sedentary lifestyle
* Can cause obesity, stress, high blood pressure and heart attack

Question 16

Explain how the rhythmic contraction of heart muscles occurs.

Answer 16

• the contraction of cardiac muscles is triggered and initiated by a group of specialised tissues known as sinoatrial node.
• sinoatrial node generates electrical impulses similar to the ones generated by nerves
• cardiac muscles are continuous and criss-cross each other, when a cell is stimulated, the stimulus is spread or conducted throughout the atrial wall of the heart
• the waves of contraction are transmitted throughout the atria causing the atria to contract simultaneously and uniformly
• the electrical impulse will then spread to a second group of nodes known as the atrioventricular node
• the electrical impulse will then spread through the bundle of His and purkinje fibres till it reaches the apex of the heart
• this induces a rhythmic electrical impulse wave throughout the ventricles and both ventricles contract simultaneously starting from the bottom to the base of the aorta and pulmonary artery

Question 17

Ali’s leg feels numb after sitting cross-legged for an hour. suggest the action to be taken and give your reasons.

Answer 17

• he needs to walk or move his feet so that the skeletal muscles on his feet can contract
• the contraction of the foot skeletal muscles produce a force that pushes blood in the veins too return to the heart
• the contraction off muscles also force blood to flow to foot tissues that suffer from a shortage of blood supply

Question 18

Elly enjoys eating beef rendang and nasi lemak. Explain why this practice of eating in the long term can affect her health.

Answer 18

• beef rendang and nasi lemak cooked with coconut milk contain high lipid (triglycerides) and cholesterol
• human body tends to store fats instead of using it to supply energy
• excess fats and cholesterol will be deposited on arterial walls(arteriosclerosis)
• the arterial lumen will become narrow, obstructing blood flow
• increases blood pressure (hypertension)
• the heart needs to work harder to pump blood
• adds ore pressure to the heart
• if the arterial lumen that becomes narrow is the coronary artery, a heart attack may occur (during an activity) or a person’s emotional condition which causes the heart to work harder
• this condition is called angina and is caused by the lack of oxygen supply to cardiac muscles
• the lack of blood and oxygen supply to the heart can cause some parts of the cardiac muscles to die
• it can also turn fatal
• if the deposits of cholesterol and fats, together with blood clots move to other parts, for example the brain, stroke may occur
• the individual should quit unhealthy eating habits in order to prevent stroke, hypertension and cardiovascular diseases

Question 19

A baby is born with a damaged bicuspid valve which cannot close tightly. Explain the effect of this condition on the baby.

Answer 19

• blood is able to flow back to the left ventricle when the left ventricle contracts to pump blood out through the aorta
• body tissues will receive less oxygenated blood
• blood circulation becomes slower and pressure drops

Question 20

A normal baby has a thick muscular heart wall that separates the left heart from the right heart. If this muscle is not formed completely, predict the outcome on the quality of blood that flows into the aorta.

Answer 20

• the incomplete septum development causes deoxygenated blood to mix with oxygenated blood
• hence the baby will experience shortage of oxygen

Question 21

How should an individual with a coronary artery that is clogged with cholesterol deposits be treated?

Answer 21

• coronary artery bypass surgery
• placing a stent in the blood vessel

Question 22

Each year, thousands of people die from excessive blood loss caused by injuries during accidents or war. One way to reduce the continuous outflow of blood from the injury is to apply pressure on the wound with a bandage. In your opinion, what adaptations can be done to the bandage to make it more efficient in stopping blood loss temporarily until patient is admitted to the hospital?

Answer 22

• contain a lot of thrombin and fibrinogen to stop blood flow
• can be used during an emergency to cover accident wound