Which statement correctly describes two organ systems working together when the body increases its movement? A
B
The excretory system releases extra waste, and the digestive system breaks down nutrients quickly to replace the waste,
The digestive system breaks down nutrients quickly, and the respiratory system delivers the nutrients to the working muscles,
The respiratory system increases gas exchange, and the circulatory system circulates blood faster to deliver oxygen to muscles,
C
D
The circulatory system picks up more carbon dioxide waste from the muscles, and the excretory system releases the carbon dioxide,

d. the circulator system picks up more carbon

the abdomen (less formally called the belly, stomach, tummy or midriff) constitutes the part of the body between the thorax (chest) and pelvis, in humans and in other vertebrates. the region occupied by the abdomen is termed the abdominal cavity. the stomach secretes acid and enzymes that digest food. ridges of muscle tissue called rugae line the stomach. the stomach muscles contract periodically, churning food to enhance digestion. the pyloric sphincter is a muscular valve that opens to allow food to pass from the stomach to the small intestine.

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