3.2 transport in animals Flashcards

Question

tissue fluid formation

Answer 1

hydrostatic pressure: - This is the pressure exerted by a fluid, e.g. blood - The hydrostatic pressure in this example is the blood pressure, generated by the contraction of the heart muscle oncotic pressure: - This is the pressure exerted by plasma proteins within a blood vessel

Answer 2

When blood is at the arterial end of a capillary the hydrostatic pressure is great enough to force fluid out of the capillary Proteins remain in the blood as they are too large to pass through the pores in the capillary wall The increased protein content creates a water potential gradient (osmotic pressure) between the capillary and the tissue fluid At the arterial end the hydrostatic pressure is greater than the osmotic pressure so the net movement of water is out of the capillaries into the tissue fluid

Answer 3

At the venous end of the capillary the hydrostatic pressure within the capillary is reduced due to increased distance from the heart and the slowing of blood flow as it passes through the capillaries The water potential gradient between the capillary and the tissue fluid remains the same as at the arterial end At the venous end the osmotic pressure is greater than the hydrostatic pressure and water begins to flow back into the capillary from the tissue fluid Roughly 90 % of the fluid lost at the arterial end of the capillary is reabsorbed at the venous end The other 10 % remains as tissue fluid and is eventually collected by lymph vessels and returned to the circulatory system If blood pressure is high (hypertension) then the pressure at the arterial end is even greater This pushes more fluid out of the capillary and fluid begins to accumulate around the tissues. This is called oedema

Answer 4

Some tissue fluid reenters the capillaries while some enters the lymph vessels The lymph vessels are separate from the circulatory system They have closed ends and large pores that allow large molecules to pass through Larger molecules that are not able to pass through the capillary wall enter the lymphatic system as lymph Small valves in the vessel walls are the entry point to the lymphatic system The liquid moves along the larger vessels of this system by compression caused by body movement. Any backflow is prevented by valves This is why people who have been sedentary on planes can experience swollen lower limbs The lymph eventually reenters the bloodstream through veins located close to the heart Any plasma proteins that have escaped from the blood are returned to the blood via the lymph capillaries If plasma proteins were not removed from tissue fluid they could lower the water potential (of the tissue fluid) and prevent the reabsorption of water into the blood in the capillaries After digestion lipids are transported from the intestines to the bloodstream by the lymph system

Answer 5

1. Wave of electrical excitation begins in SAN. This causes atria to contract and initiates heartbeat. 2. Electrical activity from SAN picked up by AVN. This stimulates the bundle of HIS 3. Bundle of HiS stimulated 4. Bundle of HiS splits into 2 branches, conducts the wave of excitation to the bottom of heart 5. The apex, the purkyne fibres spread out though the walls of the ventricles, starting at the apex. This contracts the septum starting at the apex to allow more efficient emptying of ventricle

Answer 6

lectrocardiography can be used to monitor and investigate the electrical activity of the heart Electrodes that are capable of detecting electric signals are placed on the skin These electrodes produce an electrocardiogram (ECG) An ECG shows a number of distinctive electrical waves produced by the activity of the heart A healthy heart produces a distinctive shape in an ECG

Answer 7

Caused by the depolarisation of the atria, which results in atrial contraction (systole)

Answer 8

Caused by the depolarisation of the ventricles, which results in ventricular contraction (systole) This is the largest wave because the ventricles have the largest muscle mass

Answer 9

Caused by the repolarisation of the ventricles, which results in ventricular relaxation (diastole)

Answer 10

Scientists are still uncertain of the cause of the U wave, some think it is caused by the repolarisation of the Purkyne fibres

Answer 11

When the heart beats too fast it is tachycardic An individual with a resting heart rate of over 100 bpm is said to have tachycardia

Answer 12

When the heart beats too slow it is bradycardic An individual with a resting heart rate below 60 bpm is said to have bradycardia A lot of fit individuals or athletes tend to have lower heart rates and it is usually not dangerous

Answer 13

This condition is caused by an early heartbeat followed by a pause It is common in the population and usually requires no treatment unless very severe

Answer 14

An irregular heartbeat will disrupt the rhythm of the heart Severe cases of fibrillation can be very dangerous, even fatal

Answer 15

1. HbO8 (oxyhaemoglobin) dissasociates ---> Hb + 4O2 2. O2 diffuses into plasma 3. Respiration releases CO2, carbonic anhydrase in RBC combines CO2 + H20 ---> H2CO3 (carbonic acid) 4. Dissasociation of H2CO3 ---> H+ + HCO3- (hyrodgencarbonate ions) 5. H+ + Hb ---> HHb (haemoglobonic acid) 6. HCO3- ions diffuse out of red blood cell 7. Cl- ions diffuse into red blood cell to maintain charge (chloride shift)