Fig. 4.1 shows a closed double circulation in the circulatory system. Explain what is meant by a closed double circulation.
From Fig. 4.1, identify: blood vessel W blood vessel X valve Y heart chamber Z
State which component is present in the blood at location P but absent from the lymph at location Q in Fig. 4.1.
While blood travels through the lung capillary network, gas exchange takes place. Describe the process of gas exchange between the alveolus and the blood.
As blood moves through the small intestine, small soluble products of digestion such as glucose are absorbed into the capillaries and carried to the liver. Fig. 4.2 is a transmission electron micrograph of intestinal epithelial cells. (i) Write the names of cell structures F and G in the boxes on Fig. 4.2. (ii) At the surface labelled S, glucose molecules leave the intestinal epithelial cell by facilitated diffusion. Outline the features of facilitated diffusion of glucose molecules.
In the boxes provided on Fig. 4.2, write the names of cell structures F and G.
Glucose molecules exit the intestinal epithelial cell at the surface labelled S by facilitated diffusion. Outline the features of facilitated diffusion of glucose molecules.