The main difference between pineal gland and pituitary gland is that pineal gland is important for the production of melatonin and circadian cycle regulation, while pituitary gland helps to regulate many biological processes like growth, secretion of hormones, contraction of the uterus, ovulation, spermatogenesis, and milk ejection.
There are two types of glands in the human body, namely duct glands and ductless glands. Duct glands secrete their secretions into hollow organs through ducts, while ductless glands secrete hormones. Some examples of ductless glands in the body are pituitary glands, pineal glands, gonads, thymus, pancreas, and adrenal glands. Pineal glands and pituitary glands are two types of neuroendocrine glands in the brain.
Key Areas Covered
1. What is Pineal Gland
– Definition, Structure, Function
2. What is Pituitary Gland
– Definition, Structure, Function
3. Difference Between Pineal Gland and Pituitary Gland
– Comparison of Key Differences
Key Terms
Pineal Gland, Pituitary Gland
What is Pineal Gland
The pineal gland is a highly vascularised, secretory neuroendocrine organ located in the brain. It is a small gland the size of a pea, with a weight of about 100-150mg. This gland takes the shape of a pine cone. It is located in the midline of the brain, outside the blood-brain barrier, and attached to the root of the third ventricle by a short stalk. Therefore, it is a midline brain structure that is unpaired, but it shows a left-sided bias. The pineal gland is reddish-grey in color. It consists of portions of neurons, neuroglial cells, and specialized secreting cells known as pinealocytes. These pinealocytes create melatonin.
The main function of the pineal gland is to release melatonin when the light stimuli from the eyes decrease. Melatonin is a neurohormone signal that triggers the body to fall asleep. Melatonin mainly regulates biological rhythms. This happens by increasing its concentration in blood during night time and decreasing it during the day time. It also helps in the regulation of reproductive cycles in some vertebrates.
Moreover, in very rare situations, the pineal gland is removed by surgery if a person has a pineal tumor. This is called pinealectomy.
What is Pituitary Gland
The pituitary gland is a pea-sized gland that is enclosed within a bony structure (sella turcica) at the base of the brain. The sella turcica protects the pituitary. We call it the master gland because it controls the functions of other glands. Moreover, the hypothalamus, which is a region of the brain that lies just above the pituitary, controls the pituitary gland.
Furthermore, there are two parts of the pituitary, namely the frontal lobe and the back lobe. The frontal lobe accounts for 80% of the pituitary glands’ weight. These lobes are connected to the hypothalamus by a stalk that contains blood vessels and nerve cell projections that are nerve fibers or axons. The hypothalamus controls the anterior lobe by releasing hormones through the connecting blood vessels. It also controls the posterior lobe through nerve impulses. However, hormonal production by the pituitary is not continuous. It produces hormones in time intervals of 1-3 hours, and there are alternating periods of activity and inactivity.
Additionally, the anterior lobe releases six main hormones. They are adrenocorticotropic hormone, follicle-stimulating hormone and luteinizing hormone, growth hormone, prolactin, and thyroid-stimulating hormone. Meanwhile, posterior lobe hormones are vasopressin and oxytocin.
Difference Between Pineal Gland and Pituitary Gland
Definition
The pineal gland is a highly vascularised, secretory neuroendocrine organ located in the midline of the brain, while the pituitary gland is a pea-sized gland that is enclosed within a bony structure (sella turcica) at the base of the brain.
Location
The pineal gland is located on the roof of the third ventricle of the brain, whereas the pituitary gland is located at the base of the brain.
Structure
While the pineal gland is not divided into parts, the pituitary gland is divided into two parts.
Hormones
The pineal gland secretes only one hormone, whereas the pituitary gland secretes nine hormones.
Function
Moreover, the pineal gland helps in the regulation of biological rhythms, while the pituitary gland helps to regulate many biological processes like growth, secretion of other hormones, contraction of the uterus, ovulation, spermatogenesis, and milk ejection.
Conclusion
The human body has duct glands and ductless glands. Two examples of ductless glands are the pineal gland and the pituitary gland. Moreover, the main difference between pineal gland and pituitary gland is their function. The pineal gland helps in the regulation of biological rhythms, while the pituitary gland helps to regulate many biological processes like growth, secretion of other hormones, contraction of the uterus, ovulation, spermatogenesis, and milk ejection.
Reference:
1. “Pituitary Gland.” Cleaveland Clinic.
2. “Physiology of the Pineal Gland and Melatonin.” National Library of Medicine.
Image Courtesy:
1. “Illu pituitary pineal gland” (Public Domain) via Commons Wikimedia
2. “Pituitary gland-optic chiasm-sella turcica” By Gray’s Anatomy – File:Gray715.png (Public Domain) via Commons Wikimedia
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