Ture capillaries do not have smooth muscle.

Ventilation in birds is accomplished by expansion and contraction of the ( ). A: air sacs B: trachea C: lungs D: diaphragm E: air capillaries

Which of the following structures can not be found in the epidermis？ A: Duct of sweat glands B: Capillaries C: Nerve endings D: Melanocytes

Which of the blood vessels conduct blood away from the ventricles of the heart and lead to the capillaries? A: arteries and veins B: arterioles and venules C: arteries and venules D: arteries and arterioles

Which of the followings is NOT correct about endocrine glands?() A: No duct. B: Rich in blood capillaries. C: Cells are arranged in cord, follicle, aggregation or net-like<br/>structures. D: Production is hormone. E: Production is secreted to the outside.

The arterial blood pressure: A: The mean arterial pressure of a normal young adult averages about 100 mmHg. B: Depends solely on the cardiac output. C: Is the arithmetic average of the systolic and diastolic pressures. D: Is due to the vascular resistance of the capillaries.

Moisture in food can be divided into "bound water" and "free water" according to different properties. Which of the following is not bound water? A: The first layer of water molecules adsorbed to glucose molecules B: Water molecules with unpaired electrons entering the outer empty orbits of sodium ions C: Water molecules adsorbed in capillaries in food tissue D: Water molecules bound to the negative ion of glutamic acid on the protein peptide chain