Human anatomy and glands and location
The Posterior Lobe of the Pituitary Gland or neurophpophysis stores and releases hormones secreted by the hypothalamus section of the brain including:. The thyroid is a butterfly shaped gland which is located at the base of the throat. It has two lobes separated in the middle by a strip of tissue the isthmus. The Thyroid itself secretes three main hormones:. People who have surgery to remove the thyroid gland thyroidectomy for cancer or other thyroid problems usually need to take thyroxine supplements in order to maintain normal weigh and body functions.
There are four Parathyroid glands which are small and rounded, arranged in two pairs usually located above and below the thyroid. Each Parathyroid is small, yellow and smooth, sometimes they imbed themselves in the thyroid itself.
The Adrenal Glands
Parathyroid hormone increases the blood concentrations of calcium and phosphorous, working to balance the Calcitonin which is secreted by the thyroid to maintain the body's balance of calcium. The pancreas is a long, narrow, lobed gland located behind the stomach. The Pancreas has two types of cells: exocrine and endocrine cells. The exocrine cells secrete Pancreatic juices which are used in the duodenum as an important part in the digestive system. The endocrine cells are arranged in clusters throughout the Pancreas, these known as Islets of Langerhans.
There are three types of endocrine cells; alpha cells which secrete glucagon, beta cells which secrete insulin, and delta cells which inhibit the secretion on glucagon and insulin:. The adrenal glands resemble small caps perched on top of each kidney. The Adrenal is actually a combination of two glands the adrenal cortex and the adrenal medulla.
The adrenal cortex is essential for life, as opposed to the adrenal medulla which is important but not indispensable. The anterior pituitary controls the adrenal cortex by secreting the hormone ACTH. All of the secretions of the adrenal cortex are known as steroids, many of which can now be manufactured synthetically. The adrenal cortex is made up of three layers associated with three classes of hormones:. The Adrenal Medulla is the inner part of the adrenal gland. The hormones secreted effect the structures in the body that are under the control of the sympathetic nervous system, aiding the body to deal with stressful situations such as fright, attack or pursuit.
They are both associated with an increased heart beat, higher blood pressure, and higher blood glucose levels, thus preparing the body for quick action. The gonads consist of ovaries in the female and testes in the male.
What Is a Gland?
These glands produce hormones important in the development and functioning of the reproductive organs. Male testes are egg shaped glands located in the sac like scrotum, and serve two main functions: i The production of sperm cells, and ii The secretion of testosterone. Testosterone is the masculizing hormone inducing male secondary sexual characteristics after puberty.
Female ovaries are two almond shaped glands on each side of the uterus. They have three main functions; i Containing immature ova eggs , ii The secretion of oestrogen, and ii the secretion of progesterone. Mucous glands are involved in the production of mucus, a viscid sticky glycoprotein. Mixed glands are comprised of both serous and mucous glands and secrete a mixed substance containing both serous fluid and mucus. Exocrine glands can also be categorised into another 3 subtypes according to their secretion mechanism:.
Merocrine glands are the most common and release their secretory products via exocytosis. The major secretory products of these glands are usually proteins. Apocrine glands release their secretory products contained within membrane-bound vesicles. This type of secretion is rare and these glands are found in the breast and constitute some sweat glands. Holocrine glands release whole secretory cells, which later disintegrate to release the secretory products.
This type of secretion is seen in sebaceous glands associated with hair follicles. The release of secretory products from the secretory unit is aided by some contractile cells, known as myoepithelial cells. These cells comprise characteristics of both muscle and epithelial cells and lie between the secretory unit and basement membrane. The cytoplasmic processes of these cells envelop the secretory unit so that contraction of these cells results in release of the secretory products from the secretory units and into the ducts.
Where in the human body is the pituitary gland located? | Socratic
Release of secretory products occurs in response to stimulation by hormones or autonomic nerve impulses. Endocrine glands release their secretory products directly into the bloodstream, rather than via a duct. These trabeculae provide internal support and give the gland a lobular appearance. Endocrine glands release secretions known as hormones , which travel via the bloodstream to reach their target cells, where they elicit functional changes. The hormones are commonly stored intracellularly within secretory vesicles and are released intermittently via exocytosis.
An exception to this is the thyroid gland , which stores its hormone extracellularly as an inactive precursor molecule. Secretion of hormones is usually regulated by negative feedback , where a rise in the level of hormone in the blood decreases its secretion. Sebaceous glands are simple, branched, acinar, exocrine glands located within the skin.
They secrete a fatty substance sebum , into the follicular duct , which surrounds the hair shaft. Sebum helps keep the skin flexible and prevents water loss.
These are known as holocrine glands, as sebum is released when the secretory cells degenerate. The pituitary gland is a small endocrine gland within the brain involved in hormone synthesis and regulation. It consists of two parts, the anterior pituitary or adenohypophysis , and the posterior pituitary , or neurohypophysis. The anterior pituitary secretes:. ACTH and TSH travel to their target organs, the adrenal gland and the thyroid gland , respectively in order to stimulate the release of further hormones.
The posterior pituitary secretes antidiuretic hormone ADH , otherwise known as vasopressin, and oxytocin. The pancreas is an organ comprised of both exocrine and endocrine glands. The majority of the pancreas has an exocrine function and secretes an enzyme-rich alkaline fluid into the pancreatic duct , which joins the common bile duct before emptying into the duodenum.
The exocrine glands secrete the proteolytic enzymes trypsinogen and chymotrypsinogen , which are activated to trypsin and chymotrypsin in the duodenum and aid in digestion. The exocrine pancreas also secretes bicarbonate ions , which neutralise the acidic chyme as it reaches the duodenum.
There are also clusters of endocrine glands located within the exocrine tissue and these are referred to as islets of Langerhans. The two main hormones released from the endocrine glands of the pancreas are insulin and glucagon. The pancreas also secretes:. They consist of abnormal glands and can secrete mucus. Treatment can involve solely surgery, chemotherapy or radiotherapy or a combination of these. Adenomas are the benign counterparts of adenocarcinomas and are commonly found in the pituitary gland.
Pituitary adenomas do not invade the surrounding tissues, but they can have serious consequences due to compression on surrounding structures such as the optic chiasm, which can lead to visual problems. Hyperfunctioning of an endocrine gland such as the thyroid gland, pituitary gland or adrenal gland can lead to increased secretion of hormones.
Treatment can involve pharmacotherapy such as carbimazole or propylthiouracil, surgery or radioiodine therapy. A hypofunctioning endocrine gland can also occur resulting in a reduced production of hormones. An example of this is hypopituitarism , where production of one or more of the hormones of the pituitary gland, is reduced. Treatment can involve hormone replacement, surgery or radiation therapy. Another example of a disease due to hypofunction is type I diabetes mellitus , where autoimmune destruction of the beta cells of the pancreas leads to reduced insulin in the bloodstream.
This can lead to polyuria increased urination and polydipsia Increased thirst due to a reduction in glucose storage.
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Treatment involves daily insulin injections and blood glucose monitoring to try and prevent complications such as diabetic nephropathy kidney damage and diabetic neuropathy damage to the nerves. Learning anatomy is a massive undertaking, and we're here to help you pass with flying colours. Login Register.
12: The Endocrine System (Hormones)
Basics Terminology First look at bones and muscles First look at neurovasculature First look at the systems. Upper extremity Shoulder and arm Elbow and forearm Wrist and hand Neurovasculature of the upper limb. Lower extremity Hip and thigh Knee and leg Ankle and foot Neurovasculature of the lower limb. Trunk wall Vertebral column Dorsal trunk Ventral trunk. Abdomen and pelvis Peritoneal cavity Stomach Spleen Liver Pancreas Small intestine Large intestine Kidneys Ureter Pelvis Urinary bladder and urethra Female reproductive organs Male reproductive organs Blood vessels of the abdomen and pelvis Lymphatics of the abdomen and the pelvis.
Neuroanatomy Cerebrum Subcortical structures Cerebellum and brainstem Ventricles, meninges and blood vessels of the brain Spinal cord Pathways of the nervous system Cranial nerves Peripheral nervous system. General Introduction to cells and tissues Epithelial tissue Connective tissue Nervous tissue Muscle tissue Cartilage and bone. Systems Cardiovascular system Nervous system Integumentary system Musculoskeletal system Respiratory system Excretory system Endocrine system Digestive system Lymphatic system Male reproductive system Female reproductive system.
Fetal tissues Head and neck Trunk and limbs. Medical imaging. Thorax Chest X-ray. Anatomy Basics First look at the systems. Glands: want to learn more about it? Sign up for your free Kenhub account today and join over 1,, successful anatomy students.