Pituitary gland parts - Tamil \ Anterior & posterior lobe Infundibulum, Pituitary stalk‪@lovemedics‬

‪@lovemedics‬ Pituitary gland - parts HYPOTHALAMUS: It is a small, vital region in the diencephalon part of the brain, located below the thalamus & above the brainstem. It plays a crucial role in regulating various bodily functions, including: 1. Body temperature 2. Hunger and thirst 3. Sleep-wake cycles (circadian rhythms) 4. Hormone secretion 5. Emotional responses 6. Heart rate & blood pressure 7. Digestion & metabolism 8. Reproductive processes Pituitary gland: It is a small, pea-sized endocrine gland located at the base of the brain, below the hypothalamus. Functions: 1. Hormone regulation: Produces & secretes hormones that control other endocrine glands. 2. Growth & development: Regulates growth hormone production. 3. Metabolism: Influences thyroid hormone production. 4. Reproductive processes: Regulates reproductive hormones (FSH, LH, prolactin). 5. Electrolyte balance: Helps maintain electrolyte balance through ADH (antidiuretic hormone) regulation. 1. Pars tuberalis: It is a part of the adenohypophysis, which is the anterior (front) lobe of the pituitary gland. Location: Lateral portions of the pituitary gland Function: Produces hormones like thyroid-stimulating hormone (TSH) and follicle-stimulating hormone (FSH) 2. Pars intermedia: Location: Narrow zone b/w the pars distalis & pars nervosa Function: Produces hormones like adrenocorticotropic hormone (ACTH) & melanocyte-stimulating hormone (MSH) 3. Pars distalis: Location: Anterior (front) lobe of the pituitary gland Function: Produces hormones like growth hormone (GH), prolactin (PRL) , ACTH Median eminence: It connecting the hypothalamus to the pituitary gland. It is a vital structure in the hypothalamic-pituitary axis. 1. Hormone secretion 2. Growth & development 3. Metabolism 4. Electrolyte balance 5. Reproductive processes The median eminence acts as a bridge, allowing neurohormones produced by the hypothalamus to reach the pituitary gland, stimulating or inhibiting the release of pituitary hormones. Infundibulum: Funnel-shaped structure that connects the hypothalamus to the posterior pituitary gland. It plays a crucial role in the hypothalamic-pituitary axis, facilitating the transport of hormones & neurohormones b/w the two regions. Functions 1. Hormone transport: Allows hypothalamic hormones to reach the posterior pituitary gland. 2. Neurohormone secretion. 3. Pituitary gland connection. The infundibulum stalk / pituitary stalk: It connects the hypothalamus to the pituitary gland. It is a vital part of the hypothalamic-pituitary axis The infundibulum stalk contains: 1. Axons: Nerve fibers that transmit signals from the hypothalamus to the pituitary gland. 2. Blood vessels: Supplies oxygen and nutrients to the pituitary gland. 3. Hormone-producing cells: Produces and transports hormones like oxytocin and ADH. Funnel (infundibulum) Narrow tube (infundibulum stalk) The pars nervosa / neural lobe / posterior lobe: It is the posterior (back) part of the pituitary gland. It is a vital structure that plays a crucial role in hormone regulation and secretion. Functions of the pars nervosa: 1. Hormone storage and release: Stores and releases oxytocin and antidiuretic hormone (ADH) produced by the hypothalamus. 2. Neurosecretion: Releases hormones directly into the bloodstream. 3. Axonal transport: Allows axons from the hypothalamus to reach the pituitary gland. Characteristics of the pars nervosa: 1. Neural tissue: Composed of neural tissue, unlike the anterior pituitary gland, which is composed of epithelial tissue. 2. Axon terminals: Contains axon terminals from the hypothalamus, which release hormones. 3. Blood supply: Has a rich blood supply, allowing for efficient hormone transport. sella turcica is a small, saddle-shaped depression in the sphenoid bone of the skull. It is located: 1. In the middle cranial fossa 2. Behind the nasal cavity 3. Below the pituitary gland The sella turcica serves as a housing for the pituitary gland, protecting it and providing a secure environment. The hypothalamo-hypophyseal portal system (HHPS) is a specialized circulatory system that connects the hypothalamus & the pituitary gland. 1. Hypothalamic capillaries: Specialized blood vessels in the hypothalamus. 2. Portal veins: Small veins that carry blood from the hypothalamus to the pituitary gland. HHPS hormones: 1. Releasing hormones (e.g., TRH, CRH, GnRH): Stimulate pituitary hormone secretion. 2. Inhibiting hormones (e.g., somatostatin, dopamine): Inhibit pituitary hormone secretion. Optic chiasma / optic chiasm is a critical structure in the visual pathway, located at the base of the brain, directly above the pituitary gland. Function: 1. Crossing of optic nerves: It is the point where the optic nerves from each eye cross over. 2. Binocular vision: The optic chiasma enables the combination of images from each eye, creating a single, unified visual perception.