Human Circulatory System

This is the correct answer. In the circulatory system, blood flows through three types of vessels. These are veins, arteries and capillaries.

This is the correct answer as all the statements are correct.

Arteries are thick walled blood vessels which carry blood from heart to all parts of the body.

Veins are thin walled blood vessels that carry blood from organs to the heart.

The pulmonary and the umbilical arteries carry deoxygenated blood.

At high altitudes, atmospheric pressure decreases significantly while blood pressure remains relatively constant. This pressure differential causes blood vessels in the nose (which are delicate and close to the surface) to rupture, resulting in nosebleeds. The external pressure drops more than internal blood pressure adjusts, creating outward pressure on capillary walls.

Blood follows the path: heart (right ventricle) to lungs (oxygenation) back to heart (left atrium) then to body tissues. This describes the double circulation pattern with pulmonary and systemic circuits.

The hepatic portal vein carries nutrient-rich blood from the alimentary canal (stomach, intestines) directly to the liver for processing before it enters general circulation. The hepatic artery supplies oxygenated blood to the liver, and the hepatic vein drains processed blood FROM the liver. The portal vein's unique function is first-pass nutrient processing.

The skeletal system provides structural support and enables movement through bones, joints, and muscles working together. The excretory system removes waste (kidneys, bladder). The circulatory system transports blood (heart, blood vessels). The respiratory system handles gas exchange (lungs). The skeleton is literally the framework that supports the body.

Veins carry deoxygenated blood from body tissues back to the heart's right atrium, while arteries carry oxygenated blood away from the heart. The veins have valves to prevent backflow since the blood pressure is lower in the venous system. This distinction is fundamental to understanding circulatory system function.

Arteries are blood vessels that carry blood away from the heart to the body's tissues. They have thick, muscular walls to withstand the high pressure generated by the heart's pumping action. Veins carry blood back to the heart, not away from it.

Veins are blood vessels that return blood from the body's tissues back to the heart. They have thinner walls than arteries and contain valves to prevent backflow. Capillaries are tiny vessels where exchange of materials occurs, not the main transport vessels back to heart.

Animals with four-chambered hearts have double circulation: pulmonary circulation (heart to lungs and back) and systemic circulation (heart to body and back). This prevents mixing of oxygenated and deoxygenated blood. Single circulation occurs in fish with two-chambered hearts.

Fish have two-chambered hearts (one atrium, one ventricle) and single circulation. Blood passes through the heart once in a complete circuit: heart → gills → body → back to heart. This is less efficient than double circulation but adequate for their aquatic lifestyle.

Systolic pressure is the maximum pressure in arteries during ventricular contraction (systole). This is when blood is forcefully ejected from the heart into the aorta. Diastolic pressure is the minimum during relaxation, not the maximum.

Systemic circulation refers to the movement of blood from the heart to the entire body (excluding lungs) and back to the heart. Pulmonary circulation specifically involves circulation between heart and lungs. Since the question mentions 'rest of body' (not lungs), the correct answer is systemic circulation only.