Key Area 2.3 Metabolic rate Oxygen delivery and consumption Metabolic rates linked to oxygen Physiology of circulatory systems in variety of organisms Adaptations of animals in low oxygen environments

Starter Quizlet live! on respiration

Measuring metabolic rate Learning Outcomes How is metabolic rate determined? How can metabolic rate be measured?

glucose + oxygen  carbon dioxide + water + energy Metabolic rate The quantity of energy consumed by an organism per unit of time is called its metabolic rate. Energy is generated by aerobic respiration in cells glucose + oxygen  carbon dioxide + water + energy 4

Measuring metabolic rate glucose + oxygen  carbon dioxide + water + energy Metabolic rate can be measured as: Oxygen consumption per unit time. Carbon dioxide production per unit time. Energy production (heat) per unit time. 5

Basal metabolic rate Basal metabolic rate (BMR) is energy consumed by an organism at rest. Suggest 2 processes that will increase metabolic rate from BMR. Increased physical activity Digesting and processing food 6

Basal metabolic rate Animal Mass (kg) BMR (watt = J s-1) Watt/kg (to 1d.p) Dove 0.16 0.97 6.1 Rat 0.26 1.45 5.6 Sheep 45 50 1.1 Human (female) 60 68 Human (male) 70 87 1.2 Suggest why the dove has the highest wattage per Kg. They fly.... High SA:Volume ratio 7

Direct calorimetry A calorimeter measures heat produced by an organism over a period of time. Heat produced is transferred to surrounding water Temperature is measured over a period of time This allows metabolic rate top be calculated 8

Indirect calorimetry A respirometer measures O₂ uptake or CO₂ output of an organism over a period of time. Air with CO2 removed is used by the organism The CO2 it breaths out is also absorbed This decreases the volume of air in the system, drawing the liquid up the tube. Volume of CO2 absorbed = volume of O2 used. 9

Homework ERQ Questions Q1.Give an account of glycolysis and the citric acid cycle in cells (10) Q2. Give an account of the structure of a mitochondrion and the role of the cytochrome system in respiration (10)

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Physiology and metabolic rate Learning Intentions Describe physiology of circulatory systems in variety of organisms and relate differenced to oxygen consumption.

Demand An organisms metabolic rate increases to meet increasing energy demand, therefore; Consumption of oxygen increases Aerobic respiration increases Animals with high metabolic rates need efficient transport systems to deliver a large volume of oxygen to respiring cells. 14

Vertebrates Vertebrates have a closed circulatory system. All the blood is contained in a continuous circuit. The arrangement of the heart and vessels differs between vertebrate groups. State the function of capillaries in vertebrates. 15

Single circulatory system Blood only passes through the 2 chambered heart once in each circuit. Pressure goes from high in major vessels to low in the capillary beds. 16

Double circulatory system Blood passes through the heart twice in each circuit. Blood is pumped from high pressure ensuring flow to all parts. This is far more efficient than the single circulatory system. 17

Double incomplete In amphibians and reptiles the system is ‘incomplete’ because there is only one ventricle. Deoxygenated blood from the body and oxygenated blood from the lungs are mixed. Amphibians diffuse oxygen from their moist skin too. 18

Double complete In birds and mammals the system is ‘complete’ because there are two ventricles. This means that oxygenated and deoxygenated blood does not mix. This is the most advanced and efficient system. 19

Amphibian lungs Amphibians exchange gasses through their skin and mouth . They only use their lungs during vigorous activity. They have a limited surface area and few alveoli. 20

Reptiles and mammals These organisms have a system of branching tubes and many alveoli. This gives a large surface area for gas exchange. 21

Bird lungs Birds are the most active vertebrates so need more oxygen for respiration. They have several large air sacs below the lungs acting as bellows. 22

Bird lungs When the bird inhales the anterior sacs fill with stale air. When the bird exhales fresh air passes from posterior sacs to the lungs. Stale air moves from the anterior sacs to the external environment. Parabronchi Parabronchi increases uptake of oxygen. 23

Physiological adaptations to low oxygen environments Learning Intentions Describe the physiological adaptations animals possess in low oxygen environments.

Atmospheric oxygen As the level of atmospheric O₂ animals evolved and became more complex as they could be supported by the increasing concentration. As evolution continued, body size reached maximum level determined by other limiting factors. 26

Blood in humans Humans function best where oxygen in the air is 20%. If a person moves to higher altitude they gain less oxygen per breath because the air has a lower oxygen %. The body responds by producing a hormone to increase the number of red blood cells to carry more oxygen. 27

Cardiovascular fitness Maximum oxygen uptake (VO₂max) is the maximum volume of oxygen a person can take up and use during exercise. VO₂max increases with training and decreases with age. VO₂max is the best indicator of a person’s cardiovascular fitness. 28

Measuring VO₂max An O₂/CO₂ analyser is fitted and exercise is performed on a treadmill or exercise bike. Workload is gradually increased from moderate to maximum. VO₂max is reached when oxygen consumption is steady despite more challenging exercise. 29

Deep-diving Mammals like dolphins, seals and whales take deep water dives despite breathing air at the surface. Their cardiovascular systems are specially adapted. 30

Diving adaptations Heart rate slows from 125 to 10 BPM. Lungs partially collapse as external water pressure increases. Air in the alveoli is compressed so the animals are less buoyant and can sink. 31