Download 5A Worksheet KEY

BIOL 255 SI, Molly
Unit 5A, 11/28/16
1) Endocrine glands secrete hormones into extracellular spaces to capillaries where they bind to the
receptors on target cells, exerting their effects.
2) The functions of endocrine glands are to maintain homeostasis, as in the chemical composition and
volume of interstitial fluid, metabolism and energy balance, smooth and cardiac muscle activity,
glandular secretions, the immune system, growth and development, reproduction, and circadian
rhythm.
3) The pituitary gland or hypophysis, is a two lobed organ that secretes nine major hormones. It is
referred to as the “Master Gland” under the control of its ”King” the hypothalamus. The
neurohypophysis which is the posterior pituitary gland, is made up of neural tissue and is an extension
of the nervous system. It is connected to the hypothalamus by the infundibulum by which it receives,
stores and releases hormones.
4) The adenohypophysis is the anterior pituitary gland which is made up of glandular tissue and is
more part of the endocrine system as it synthesizes and secretes hormones. It is inhibited or
stimulated by the hypothalamus.
5) The posterior pituitary is actually part of the brain with neural connections to the hypothalamus
which is referred to as the hypothalamic-hypophyseal tract. It is the nuclei of the hypothalamus that
synthesize oxytocin and antidiuretic hormone (ADH) and these hormones are transported to the
posterior pituitary to be released.
6) The anterior pituitary gland develops as an extension of the oral mucosa which means it is derived
from the endoderm and has no direct neural connection with the hypothalamus. It does have vascular
connection through the hypophyseal portal system which is comprised of the primary capillary plexus
of the hypothalamo-hypophyseal portal veins and the secondary capillary plexus.
7) Anterior pituitary hormones include the growth hormone that is made by the somatotroph cells
which stimulate the liver and other tissues to secrete insulin-like growth factors that stimulate
growth and repair.
8) Another anterior pituitary hormone is the thyroid-stimulating hormone (TSH) which is made by the
thyrotroph cells and these control thyroid hormone production, which control the metabolic rate.
Another hormone is the adrenocorticotropic hormone (ACTH) which is made by the corticotroph cells
that control the adrenal cortex’s corticosteroid production.
9) Also anterior pituitary hormones are Follicle-stimulating hormone (FSH) which is made by the
gonadotroph cells that control egg and sperm production, Luteinizing hormone (LH) that are also made
by the gonotroph cells that control sex hormone production, Prolactin (PRL) which is made by the
lactotroph cells that control milk production and finally Melanocyte-stimulating hormone (MSH) which
stimulates melanocytes of the epidermis.
10) The hormones that are released by the axon terminals of the posterior pituitary are Antidiuretic
hormone (ADH) - which influences water balance, preventing dilute urine formation - and Oxytocin
which stimulates smooth muscle contractions in breasts causing milk let down and the uterus during
child birth. Afterwards, it also plays a role in care-giving and sexual arousal and satisfaction.
11) The thyroid gland is the largest endocrine gland and has two lateral lobes just below the larynx
which is connected by the isthmus. It is composed of small follicles or sacs that produce
thyroglobulin which is a glycoprotein that is secreted by exocytosis into the colloid, a protein rich
fluid in the follicle lumen where iodine mixes with the thyroglobulin which becomes the precursor to
thyroid hormone. Other endocrine cells called parafollicular cells produce calcitonin.
12) Calcitonin is a peptide hormone produced by parafollicular cells that lowers blood calcium levels in
children as bone is mineralized and is an antagonist to the parathyroid hormone (PTH).
13) The pineal gland is a small gland hanging from the roof of the third ventricle of the brain which
secretes melatonin that increases at night and decrease during the day. Physiological processes
showing rhythmic variations such as in body temperature, sleep and appetite.