Chapter 9 Flashcards
Transport in Animals (19 cards)
Describe the circulatory system
a system of blood vessels with a pump and valves to ensure one-way flow of blood
Describe the circulatory system of a fish
single circulatory system – heart has two chambers (one receiving blood and one pumping it) – pumps blood to gills to get oxygenated – flows to al organs – returns to heart
blood goes through the heart only once for each complete circulation of the body;
Describe the circulatory system of a mammal
Double circulatory system:
Blood passes through the heart twice for each complete circulation of the body.
The right side of the heart collects deoxygenated blood from the body and pumps it to the lungs. The left side collects oxygenated blood from the lungs and pumps it to the body.
Explain the advantages of a double circulation
In single circulatory systems, pressure lost as the blood passes through the gills capillaries and is not gained back up again until the blood returns to the heart, oxygenated and deoxygenated blood are not kept separate. The double circulatory system helps to maintain blood pressure, and keeps oxygenated and deoxygenated blood separate, making circulation efficient.
Structure of heart
!! refer to diagram !!
The right atrium receives deoxygenated blood from the vena cava and contracts to pump it (through the atrioventricular valves) into the right ventricle which contracts to push the blood up the pulmonary artery (through the semilunar valves) which takes the blood from the <3 to the lungs to get oxygenated then returning via the pulmonary vein to the left atrium which contracts to pump it into the left ventricle (through the atrioventricular valves) which contracts to pump the blood into the aorta (through the semilunar valves) to be sent to all the organs
septum in between – separates oxygenated and deoxygenated blood
The wall of the left ventricle is much thicker than the wall of the right ventricle because it needs to build up enough pressure to pump the blood to all of the main organs. The right ventricle pumps blood only to the lungs, which is a shorter distance.
The walls of the atria are much thinner than those of the ventricles; contraction of the atria only needs to be powerful enough to move blood down into the ventricles, while the ventricles are moving blood around the body and through all of the organs
Ways of monitoring heart activity
– ECG
– pulse rate
– listening to sounds of valves closing
Describe and explain the effect of physical activity on the heart rate
During exercise, oxygen and glucose are needed to allow the muscles to respire aerobically, so they have sufficient energy to contract; the heart rate increases (to supply the muscles with more oxygen rich blood) and stays high until physical activity slows down or stops, after exercise, the heart rate gradually returns to normal.
Describe coronary heart disease
caused by blockage of the coronary arteries, which supply the heart muscle with oxygen and glucose. Without these, the muscle cells stop aerobic respiration no energy for contracting and die (a heart attack)
risk factors:
– Poor diet with too much saturated (animal) fat
→ leads to fatty deposits (atheroma) in arteries, which eventually block the blood vessel or allow a blood clot to form which can get trapped in capillaries and block them cuz of its size
– Lack of exercise: heart muscle loses its tone & becomes less efficient in pumping blood
– Obesity: puts extra strain on the heart and makes it more difficult for the person to exercise
– Smoking: nicotine damages the heart & blood vessels
– Stress: increase blood pressure, → fatty materials collects in the arteries
– Genetic predisposition: passed on in generations
– Age: risk increases with age
– Sex: males are more at risk than females
How risk of CHD is reduced
Maintaining a healthy, balanced diet will lower the chance of a person becoming obese., low intake of saturated fats that is part of a balanced diet reduces the chances of a build-up of fatty deposits and the formation of blood clots.
Regular, vigorous exercise increases muscle tone – not only of skeletal muscle, but also of cardiac muscle leads to an improved coronary blood flow and the heart requires less effort to keep pumping. An obese person is less likely to take regular exercise.
Describe the roles of the 3 blood vessels
Arteries: carry blood, at high pressure, away from the heart to the organs of the body.
Veins :return blood, at low pressure, from the organs towards the heart.
Capillaries: link arteries to veins, carry blood through organs and tissues, allowing materials to be exchanged.
Describe and explain the structure of arteries
Thick, tough wall with muscles, elastic fibres and fibrous tissue: high pressure – prevents bursting and maintains pressure wave
Narrow lumen, but increases as a pulse of blood passes through to maintain blood pressure
Valves absent - high pressure already prevents blood backflo
Describe and explain the structure of veins
Thin wall of mainly fibrous tissue, with little muscle and few elastic fibres - low blood pressure
Large lumen: reduces resistance to blood flow
Valves present to prevent backflow of blood
Describe and explain the structure of capillaries
Permeable wall, one cell thick, with no muscle or elastic tissue - allows diffusion of materials between capillary and
surrounding tissues WBC can squeeze between cells of the wall
Lumen approximately one RBC wide: RBCs pass through slowly to allow diffusion of materials and tissue fluid
Valves absent - blood is still under pressure
What are the blood vessels related to the heart, lungs, kidneys and liver
<3: vena cava and aorta + pulmonary artery and vein
lungs: pulmonary artery and pulmonary vein
kidney: renal artery and renal vein
liver: hepatic artery and hepatic vein + hepatic portal vein (brings products of digestion from the intestine)
List the components of blood
red blood cells, white blood cells, platelets and plasma
State the function of RBCs
biconcave discs with no nucleus - transport O₂ combines with haemoglobin to form oxyhaemoglobin. The O₂ is released from the RBCs in capillaries where surrounding O₂ levels are lower
State the function of WBCs
provide the body with immunity against pathogens
– phagocytes: engulf pathogens & digest them secreting enzymes (phagocytosis) → lobed nucleus
– lymphocytes: produce antibodies to fight bacteria and foreign materials → one large nucleus
State the function of plasma
State the function of platelets
form blood clots, which stop blood loss at a wound and prevent the entry of pathogens into the body
→ clump together when tissues are damaged and block the smaller capillaries, produce a substance that acts on a soluble plasma protein fibrinogen changing it to insoluble fibrin, which forms a network of fibres across the wound. RBCs get trapped in this network and so form a blood clot. The clot stops further loss of blood & prevents the entry of pathogens into the wound.
