The Heart Anatomy

Human Heart Size and Structure

• The human heart is approximately the size of a fist, averaging around 12 cm in length and 8-10 cm in width.
• The heart consists of four chambers: two atria and two ventricles.

Heart Valves Function

• Heart valves prevent the backflow of blood, ensuring it flows in the correct direction through the heart and into the arteries.

Layers of the Heart Wall

• The heart wall is made up of three layers: the epicardium (outer layer), myocardium (muscular middle layer), and endocardium (inner layer).

Mammalian Heart Chambers

• Most mammals, including humans, have a four-chambered heart which efficiently separates oxygenated and deoxygenated blood.

Heart Location in Vertebrates

• The heart is typically located in the thoracic cavity, slightly left of the midline, between the lungs.

Circadian Adjustment and Signal Cells

• Specialized cells called retinal ganglion cells send signals to the suprachiasmatic nuclei of the hypothalamus to help regulate circadian rhythms.

Primary Function of Eyes

• The primary function of eyes is to collect and process light, allowing for vision and perception of the surrounding environment.

Collection of Light in Higher Organisms

• In higher organisms, the lens focuses and collects light entering the eye to form clear images on the retina.

Eye-spots and Light Angle Reduction

• Eye-spots, known as ocelli, may be set into a pit to minimize the angle of light entering, enhancing directional vision.

Brain Area Controlling Pupillary Light Reflex

• The pretectal area of the midbrain is responsible for controlling the pupillary light reflex, adjusting pupil size in response to light.

Test your knowledge on the anatomy and function of the heart in the circulatory system. Learn about the four chambers of the heart and its role in pumping blood and distributing oxygen and nutrients throughout the body.