The Pituitary Gland: Functional Relationship with the Hypothalamus, Structure, and Physiology

Abstract

The pituitary gland is the most important endocrine gland as it controls many of the body’s functions such as growth, maturation, metabolism, reproduction and coping, responding to stress, daily rhythm, and ageing. The pituitary performs a key role in the regulation of several physiological functions in association and interactions with different hormones and growth factors. The pituitary gland is small in size and is located at the base of the skull within a depression in the sphenoid bone (sella turcica). This site allows for functional and anatomical connections with the hypothalamus via the portal blood system. The pituitary consists of two lobes: the posterior lobe (neurohypophysis) which has a rich supply of nerves and contains pituicytes, whereas the anterior lobe (adenohypophysis) has less of a nerve supply. The adenohypophysis is divided into three parts entirely derived from Rathke’s pouch; they are: (1) Pars distalis. (2) Pars intermedia located between the pars distalis and the posterior pituitary. (3) Pars tuberalis, a longitudinal collection of secretory cells with a good blood supply. The pituitary gland also contains stem cells which play role in turnover, cell differentiation, and response to physiological, pathological, and stress factors and to respond to hormonal signals. The hypothalamus is a neuroendocrine structure in the human brain involved in many body physiological functions, such as pituitary functions, circadian rhythm, stress response, homeostasis, behaviour, growth, and reproduction. This regulation is carried out partially through the hypothalamic-pituitary-adrenal axis, hypothalamic-pituitary-gonads axis, and hypothalamic-pituitary-thyroid axis. The pituitary gland secretes many hormones, the anterior pituitary produces most pituitary hormones such as growth hormones, prolactin, thyroid-stimulating hormones, adrenocorticotrophic hormone, melanocyte-stimulating hormone, follicle-stimulating hormone, and luteinizing hormone, while the posterior lobe release two neurohormones such as vasopressin and oxytocin. In addition, the pituitary gland is also involved in releasing antidiuretic hormone, somatostatin, dopamine, and gonadotropin-inhibitory hormone, appetite-regulating hormone (leptin), and vasopressin. This chapter discusses the topics related to the pituitary gland and its functional relationship with the hypothalamus.KeywordsPituitary glandHypothalamusPhysiologyAnatomyStructureStem cells