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The ovaries



The ovaries, a pair of tiny glands in the female pelvic cavity, are the most important organs of the female reproductive system. Their importance is derived from their role in producing both the female sex hormones that control reproduction and the female gametes that are fertilized to form embryos.

Each ovary is a small glandular organ about the shape and size of an almond. The ovaries are located on opposite sides of the uterus in the pelvic cavity and are attached to the uterus by the ovarian ligament. The open ends of the fallopian tubes rest just beyond the lateral surface of the ovaries to transport ova, or egg cells, to the uterus.

The endocrine glands of the lower torso



Many important organs of the endocrine system are found in the abdominal and pelvic regions of the body, including the adrenal glands and the pancreas. These glands produce hormones that play vital roles in the body’s regulation of minerals, glucose, and energy allocation. The digestive and excretory organs of this region also produce hormones to manage digestion, blood cell production, and mineral homeostasis as well.

The adrenal glands are a pair of triangular glands that are located along the superior edge of the kidneys. Each gland consists of two regions - an outer cortex and an inner medulla - that have distinct structures and functions within the gland. The medulla produces the stress hormones epinephrine (adrenaline) and norepinephrine (noradrenaline) under stimulation by the sympathetic division of the autonomic nervous system (ANS). These hormones help to augment the body’s “fight or flight” response to stress and exertion by increasing the heart’s blood output to the muscles; increasing the efficiency of the lungs; and releasing energy for the muscles to use.

The thymus gland



The thymus gland, despite containing glandular tissue and producing several hormones, is much more closely associated with the immune system than with the endocrine system. The thymus serves a vital role in the training and development of T-lymphocytes or T cells, an extremely important type of white blood cell. T cells defend the body from potentially deadly pathogens such as bacteria, viruses, and fungi.

The thymus is a soft, roughly triangular organ located in the mediastinum of the thoracic cavity anterior and superior to the heart and posterior to the sternum. It has two distinct but identical lobes that are each surrounded by a tough, fibrous capsule. Within each lobe is a superficial region of tissue called the cortex and a histologically distinct deep region called the medulla. Epithelial tissues and lymphatic tissues containing dendritic cells and macrophages make up the majority of both regions of the thymus.

The endocrine system of the upper torso



The endocrine system of the thorax contains only one gland, the thymus, but several other hormones are produced in this region by tissues containing endocrine cells. These hormones work to control aspects of the body’s immune, cardiovascular, and digestive systems.

The thymus gland is a small, triangular gland located deep to the sternum and superior to the heart. It forms a key component of the immune system that trains and develops T lymphocytes (T cells) to fight off infections. A class of hormones known collectively as thymosins are produced by the thymus and used to stimulate the production and development of T cells during childhood and puberty.

The thyroid gland



The thyroid gland is a butterfly-shaped organ located in the base of your neck. It releases hormones that control metabolism—the way your body uses energy. The thyroid's hormones regulate vital body functions, including:

- Breathing
- Heart rate
- Central and peripheral nervous systems
- Body weight
- Muscle strength
- Menstrual cycles
- Body temperature
- Cholesterol levels

The thyroid gland is about 2-inches long and lies in front of your throat below the prominence of thyroid cartilage sometimes called the Adam's apple. The thyroid has two sides called lobes that lie on either side of your windpipe, and is usually connected by a strip of thyroid tissue known as an isthmus. Some people do not have an isthmus, and instead have two separate thyroid lobes.

The pituitary gland



The pituitary gland is a pea-sized gland located in the center of the skull, inferior to the hypothalamus of the brain and posterior to the bridge of the nose. It is an important link between the nervous and endocrine systems and releases many hormones which affect growth, sexual development, metabolism and human reproduction.

The pituitary gland, also known as the hypophysis, is connected to the hypothalamus of the brain by a tiny isthmus of nervous tissue called the infundibulum. It sits within a small cavity in the sphenoid bone of the skull known as the hypophyseal fossa. Thus the sphenoid bone surrounds and protects the delicate pituitary gland from damage by external forces.

The pineal gland



The pineal gland, also known as the pineal body, is an important endocrine gland that produces the hormone melatonin. Melatonin plays a key role in the sleep/wake cycle and the body’s response to sunlight.

The parathyroid glands



The parathyroid glands are four small glands that have the sole purpose of secreting parathyroid hormone to regulate the calcium level in our bodies.

The parathyroid essentially helps the nervous and muscular systems function properly. Calcium is the primary element that causes muscles to contract, and calcium levels are very important to the normal conduction of electrical currents along nerves.

The hypothalamus

The hypothalamus


The hypothalamus is a section of the brain responsible for the production of many of the body’s essential hormones, chemical substances that help control different cells and organs. The hormones from the hypothalamus govern physiologic functions such as temperature regulation, thirst, hunger, sleep, mood, sex drive, and the release of other hormones within the body. This area of the brain houses the pituitary gland and other glands in the body.

The endocrine system of the head and neck



The endocrine system of the head and neck includes the vital structures responsible for governing the release of hormones to the entire body and maintaining the body’s homeostasis. Hormones released into the bloodstream from glands in the head and neck are transported throughout the body to affect every body system.

The pineal gland, a small pinecone-shaped mass of glandular tissue in the brain, plays an important role in controlling the body’s sleep cycle. The pineal gland is attached to the brain superior to the midbrain and posterior to the thalamus. Light striking the retinas of the eyes keeps the pineal gland inactive during the day, but in the absence of light the pineal gland produces the hormone melatonin. Melatonin has a sedative effect on the nervous system and helps to set the body’s sleep-wake cycle known as the circadian rhythm.