Endocrine System Test 3

What is the endocrine system?
-Major regulatory system of the body serving to maintain homeostasis
-Composed of glands that secrete chemical signals (hormones) into the circulatory system, those hormones act on specific target organs to influence its activity
Which organs function as exocrine and endocrine?
-Pancreas (Exocrine- Secrete pancreatic juices into the pancreatic duct. Endocrine portion delivers hormones directly into the bloodstream)
-Ovaries (Exocrine- Secretion of the ova directly into the fallopian tube. Endocrine- Secretion of progesterone and estrogen directly into the bloodstream)
-Testis (Exocrine- Secrete sperm into the vas deferens. Endocine- Secretion of the hormone testosterone and androgens into the bloodstream)
-Exocrine means that the glands secrete their chemical signal functions into a duct
-Endocrine mean that the hormones are being secreted directly into the bloodstream
What is the pineal gland?
-AKA pineal body
-A tiny pine cone shaped endocrine organ size of the rice grain
-Located at the Center/Posterior aspect of the cerebral hemispheres in between the medial aspect of the right and left cerebral hemispheres
-Secretes melatonin which is responsible for wake/sleep patterns in vertebrates
What is the pituitary gland?
-AKA hypophysis and chief endocrine gland because of all of the hormones it secretes that affect other organs
-Size of a pea
-Sits in the hypophyseal fossa space inferior to the sella turcica of the sphenoid bone
-Inferior to the hypothalamus and connected to the hypothalamus by the infundibulum (Hypothalamus affects the activity of the pituitary gland and acts as a link between the CNS and Endocrine System)
-Divided into two parts the posterior and anterior pituitary
-Located in the anterior aspect between the right and left cerebral hemispheres
What are the parts of the pituitary gland?
-Anteriorly anterior pituitary (Adeno-hypophyses) inhibits or stimulate other glands. Most hormones are released from this area
-Posteriorly posterior pituitary (neurohypophyses) an extension of the nervous system that stores and secretes hormones that are synthesized by the hypothalamus (Oxytoxin and ADH)
What are the parts of the anterior pituitary gland?
-Pars tuberalis (Between infundibulum and pars intermedia)
-Pars intermedia (Between posterior pituitary and pars distalis)
-Pars distalis (Fat enlarged area) (Most hormones are synthesized here)
Which glands are located in the thoracic region?
What is the thyroid gland?
-Butterfly shaped
-Bilobed gland
-Both lobes are connected by a band of thyroid tissue known as the isthmus
-Produces, stores and secretes T4, T3 and calcitonin (Secreted when calcium levels are high)
What are the boundaries of the thyroid gland?
-Inferior to the thyroid cartilage
-Lobes are lateral to the trachea
-Isthmus is anterior to the trachea
What is the function of the vagus nerve (Right and Left) in the thyroid gland? What are its branches?
-Innervates the thyroid and the larynx
-Damaged to these nerves can lead to total loss of sound
The two branches are:
-Right recurrent laryngeal nerve
-Left recurrent laryngeal nerve
What are the parathyroid glands?
-Located in the posterior aspect of the lobes of the thyroid gland
-Usually two pairs (Superior and inferior)
-Its function is to secrete parathyroid hormone in response to a decrease in calcium levels in the bloodstream
What is the pancreas?
-Sits in the posterior aspect of the greater curvature of the stomach
-Exocrine portion produces enzymes for digestion delivered by the pancreatic duct to the duodenum
-Endocrine portion delivers hormones directly into the bloodstream
-Delivers hormones in relationship to blood sugar levels
-Two hormones are insulin and glucagon
What are the 3 parts of the pancreas?
-Head (Close to the duodenum)
-Tail (Close to the spleen)
What is the thymus gland?
-Involved in the development and maturation of the immune system (T cells)
-Largest and most active in childhood
-After puberty it undergoes gradual shrinkage and its replaced by fat
What are the boundaries of the thymus gland?
-Inferior aspect of the neck to the thoracic region
-Anterior to the fibrous pericardium (heart)
-Posterior to the manubrium (sternum)
-Sits in the mediastinum
What are the adrenal glands?
-AKA Suprarenal glands
-Two glands located on the superior aspect of each kidney
-Right adrenal gland is pyramid shaped and is anterior/lateral to the inferior vena cava
-Left adrenal gland is crescent shaped and lateral to the descending/abdominal aorta
-Both are completely surrounded by fat which prevents them from moving and act as a shock absorber
-Each gland has a outer cortex (secrete corticosteroids-involved in stress) and an inner medulla (Release Epinephrine and norepinephrine)
-Chief function is to regulate stress levels