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endocrine glands are ____ glands
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hormones are transported via ____ and the ____ system.
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Block 4
Overview and hypophysis (pituitary) 1
| Question | Answer |
|---|---|
| endocrine glands are ____ glands | ductless |
| hormones are transported via ____ and the ____ system. | connective tissue spaces, vascular |
| What three classes of compounds do hormones include? | 1. steroid 2. small peptides, proteins, and glycoproteins 3. amino acid analogues and derivatives including catecholamines (norepinephrine and epinephrine) |
| What are steroid hormones derived from? | cholesterol |
| steroid hormones are synthesized and secreted by cells of the what? | OVARIES, TESTES, ADRENAL CORTEX |
| small peptide hormones, proteins, and glycoprotein hormones are synthesized and secreted by what cells? | hypothalamus, pituitary, thyroid, parathyroid, pancreas, enteroendocrine |
| amino acid derivative hormones are synthesized and secreted by what? | neurons and adrenal medulla |
| what are thyroid hormones? | IODINATED AMINO ACIDS |
| what are two types of hormone receptors? | 1. cell surface receptors 2. intracellular receptors |
| what do cell surface receptors interact with? | peptide hormones or catecholamines (unable to pass through cell membrane) |
| what does the activation of cell surface receptors generate? | large amounts of intracellular molecules called SECOND MESSENGERS |
| second messengers are produced by the activation of _____ proteins? | membrane-associated G proteins |
| What is the adenylate cyclase/cAMP system for? | most protein hormones and catecholamines |
| tyrosine kinase is a system for what? | insulin and epidermal growth factor. |
| phosphatidyl inositol is a system for what hormones? | oxytocin, gonadotropin-releasing hormone, angiotensin II, and neurotransmitters such as epinephrine |
| guanylate cyclase/cGMP system is for what? | ANTAGONISTIC SYSTEM FOR ACTION OF cAMP in some protein hormones |
| what do a majority of second messengers stimulate? | cell metabolism |
| what are some stimulatory second messenger molecules? | cAMP, 1,2 diacylglycerol (DAG), inositol triposphate (IP3), and calcium |
| What is an inhibitory second messenger and what does it interfere with? | cyclic guanosine monophosphate (cGMP) interferes with production of cAMP |
| second messengers alter the cell's ___ and produce ____-____ responses. | metabolism, hormone-specific |
| where are intracellular receptors localized? | mainly in nucleus |
| intracellular receptors are used by what and why? | steroid hormones and thyroid hormones because both can easily pass through cell membrane |
| intracellular receptors have 3 binding domains. they are... | 1. hormone binding region 2. dna binding region 3. amino-terminal region |
| gene expression is directly influenced by what hormones? | steroid hormones and thyroid hormones... NO SECOND MESSENGER REQUIRED |
| binding of intracellular receptors causes allosteric transformation of receptor to form that binds chr. dna and activates rna polymerase. this causes... | an increase in mRNA which results in production of new proteins that regulate cell metabolism |
| what is the largest collection of endocrine cells in the body | gastroenterohepatic system (GEP) |
| GEP cells also exercise ____ and ____ control of their own activity and ______ cells by diffusion of peptide secretions through the extracellular spaces. | autocrine, paracrine, adjacent epithelial cells |
| _____ gland and _____ gland are MORPHOLOGICALLY and FUNCTIONALLY linked in ENDOCRINE and NEUROENDOCRINE control of other endocrine organs. | pituitary gland and hypothalamus |
| what are the master organs of the endocrine system? | pituitary and hypothalamus |
| The pituitary is larger in what people? | multiparous women (who have given birth 2 or more times) |
| where does the pituitary gland reside? | sella turcica of sphenoid bone, covered by flap of dura mater called diaphragma sellae |
| how is the pituitary connected to the hypothalamus? | via infundibulum and vascular network |
| What are the two functional components of the pituitary which are derived from different embryologic structures? | 1. anterior lobe (adenohypophysis) 2. posterior lobe (neurohypophysis) |
| What does the anterior lobe of the pituitary develop from? | evagination from oropharynx ectoderm, also known as RATHKE'S POUCH, grows toward brain |
| What are the derivatives of Rathke's pouch? ** | Pars distalis (anterior wall of pouch), pars intermedia (remnant of posterior wall of pouch), pars tuberalis (lateral walls of pouch, forms collar/sheath around infundibulum) |
| What does the posterior lobe of the pituitary consist of and what is it derived from? | neural secretory tissue from diencephalon |
| What are the 2 parts of the posterior lobe of the pituitary? | PARS NERVOSA (neurosecretory axons and endings), INFUNDIBULUM (neurosecretory axons that form hypothalamohypophyseal tracts) |
| What two sets of vessels is the blood supply of the pituitary derived from? | 1. superior hypophyseal arteries supply pars tuberalis, median eminence, and infundibulum (from internal carotid and circle of willis) 2. Inferior hypophyseal arteries primarily supply pars nervosa (from internal carotid arteries) |
| arteries that supply pars tuberalis, median eminence, and infundibulum give rise to _____ capillaries | fenestrated |
| fenestrated pituitary capillaries drain into portal veins called... | hypophyseal portal veins |
| hypophyseal portal veins run along the ____ and give rise to what? | pars tubaralis, second fenestrated sinusoidal capillary network (secondary capillary plexus) |
| the hypothalamohypophyseal portal system does what? | carries neuroendocrine secretions of hypothalamic nerves from sites of release in the median eminence and infundibulum directly to the cells of the pars distalis |
| Where does most of the blood from the pituitary drain? | CAVERNOUS SINUS |
| anterior lobe of pituitary secretes hormones that regulate what? | other endocrine glands and some non-endocrine tissues |
| how are the cells of the anterior pituitary lobe arranged? | clumps and cords separated by fenestrated sinusoidal capillaries |
| Growth Hormone (GH) | growth of body |
| Prolactin (PRL) | mammary gland development, milk formation |
| Adrenocorticotropic hormone (ACTH) | maintains structure and stimulates hormone secretion from adrenal cortex |
| Follicle stimulating hormone (FSH) | follicle development in ovary, spermatogenesis in testes |
| Luteinizing hormone (LH) | stimulates formation of corpus luteum; stimulates interstitial cells of Leydig in testes to secrete testosterone |
| Thyroid stimulating hormone (TSH) | stimulates growth of thyroid gland and release of thyroid hormones |
| What are the tropic hormones of the anterior pituitary? Why? ** | ACTH, TSH, FSH, LH... regulate activity of cells in other endocrine glands |
| What are the non tropic hormones of the anterior pituitary? why? ** | GH, PRL... act directly on target organs that are not endocrine glands |
| What cells make up the pars distalis? | BASOPHILS, ACIDOPHILS, CHROMOPHOBES (identified by staining properties... better methods of identification include histochemistry, histophysiologic studies, electron microscopy, and immunocytochemistry |
| all known hormones of the anterior pituitary are ______ or _______. | small proteins or glycoproteins |
| what are the 5 functional cell types in the pars distalis? | 1. somatotropes (GH cells) 2. Lactotropes (PRL cells) 3. Corticotropes (ACTH) 4. Gonadotropes (FSH, LH) 5. Thyrotropes (TSH) |
| What do somatotropes produce? | somatotropin or growth hormone |
| What to lactotropes produce? | prolactin, INCREASE IN SIZE DURING PREGNANCY |
| What do corticotropes produce? what does it fragment into? | strong reaction with PAS reagent. produce proopiomelanocortin (POMC), which when cleaved fragments into: ACTH, B-LIPOTROPHIC HORMONE, MELANOCYTE STIMULATING HORMONE (MSH)*, B-ENDORPHIN, ENKEPHALIN |
| what do gonadotropes produce? | (basic stains) fsh, lh, may produce both, or one or the other |
| What do thyrotropes produce? | stain positively w/ PAS, produce thyrotropic hormone |
| Pars intermedia surrounds what?** | series of small cystic cavities that REPRESENT REMNANTS OF RATHKE'S POUCH, function unclear |
| Pars tuberalis cells often show immunoreactivity for what hormones? | ACTH, FSH, LH |
Created by:
shuckybean
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