Homeostasis
And the digestive system
The digestive system
When blood is pumped from the left ventricle of the heart, much of it passes down the dorsal aorta to the organs of the abdomen. Chief among these organs are those of the digestive tract.Within the digestive tract the food is broken down to nutrient molecules small enough to be absorbed by the villi of the small intestine.
The Nervous System
The Nervous system does not store nutrients, it must receive a continuous supply from blood. Any interruption to the flow of blood may bring brain damage or death. The nervous system maintains homeostasis by controlling and regulating the other parts of the body. A deviation from a normal set point acts as a stimulus to a receptor, which sends nerve impulses to a regulating center in the brain. The brain directs an effector to act in such a way that an adaptive response takes place
The Respiratory System
Oxygen-laden air is inhaled into the alveoli of the lungs by way of the structures illustrated . Blood within the pulmonary artery is oxygen-poor and contains a large concentration of carbon dioxide. As blood passes through the capillaries surrounding the alveoli, oxygen diffuses into blood and carbon dioxide diffuses out of blood into the alveoli. Thereafter, carbon dioxide is exhaled by moving from the alveoli to the nose.
The Circulatory System
The Circulatory system is composed of vessels that take blood from the heart, thin-walled capillaries where exchange occurs, and vessels that return blood to the heart. Blood is pumped by the heart simultaneously into two circuits: the pulmonary and systemic circuits. The pulmonary system takes blood through the lungs where gas exchange occurs and the systemic system transports blood to all parts of the body where exchange with tissue fluid takes place.