Lecture Final: Chapter 26

Question 1

INTERCELLULAR COMMUNICATION BY SECRETED MOLECULES

+ integration of what (5)

Answer 1

Chemical communication is slow / long lasting / and coordinates / integrates multiple organs and organ systems
– In reality, chemical and nervous communication are integrated

MAIN FOCUS = endocrine release of hormones into bloodstream → control and integrate the following

1. Reproduction
2. Growth and development
3. Maintenance of electrolyte / H2O / nutrient balance → remember ADH?
4. Regulation of cellular metabolism → thyroid hormone
5. Mobilization of body defenses

Question 2

Define the following:

• endocrine
• neurocrine
• paracrine
• autocrine

Answer 2

Endocrine: no duct; release into blood by true epithelial cell; only those with receptors will respond

Neurocine: same but released by neural cell

Paracrine: same but release into local interstitial fluid to stimulate neighbors

Autocrine: same but stimulate self

Question 3

Water Soluble Hormones (3)

• hypothalamus (3)
• pituitary 2, A and P
• pancreas (2)
• pineal
• adrenal medulla (2)

Answer 3

1. hydrophilic, therefore can be stored in secretory vesicles
2. captured transmembrane receptors for secondary messenger systems, which will amplify the message
3. transported through blood but short half-life bc removed by kidneys

Hypothalamus: luteinizing hormone, follicle stimulating hormone; also stimulates hormones from pituitary as well

Pituitary: growth hormone, thyroid stimulating hormone (thyroxine)

• • anterior: ACTH
• • posterior: oxytocin

Pancreas: insulin, glucagon

Pineal: melatonin

Adrenal medulla: norepinephrine, epinephrine (aka tyrosine based catecholamines)

Question 4

Lipid soluble hormones (3)

• adrenal cortex (5)
• thyroid glands

Answer 4

1. hydrophobic, therefore cannot be stored in secretory vesicles bc will diffuse right through – instead, will be created on demand
2. captured by receptors inside the cell, activating genes and the synthesis of new proteins
3. bound to plasma proteins, therefore long half life bc metabolized in liver

Adrenal cortex: glucocorticoids, mineralcorticoids; estrogen; progesterone; androgens (last three are steroid hormones)

Thyroid glands: thyroid hormones (tyrosine based)

Question 5

Transmembrane receptors

Answer 5

G protein coupled receptors (GPCR) – incl ADH, glucagon, rhodopsin (captures photons)
– GPCR is the largest family of hormone receptors

Protein / peptides / catecholamines cannot pass through membrane bc WATER SOLUBLE – will need to bind to something on extracellular face

THREE DOMAINS

1. Extracellular, high affinity hormone binding domain –induces a conformational shift in all three domains
2. One to seven hydrophobic transmembrane domain
3. Cytosolic domain linked to signaling proteins in a single transduction pathway
   - - transduces into activation of one or more intracellular signalling molecules
   - - Intracellular signalling molecules will act on effector proteins, which will modify cellular function

Question 6

Intracellular Receptors

Answer 6

Concerns steroid hormones and thyroid hormones
– structurally similar and belong to same nuclear hormone receptor family THEREFORE nuclear hormone receptors act as transcriptional regulators

1. Hormone-receptor complex binds to specific DNA sequence (aka hormone response element close to promoter of a gene)
2. HRC acts like a transcription factor to stimulate gene expression
3. pre-mRNA processed inside nucleus into mRNA, exported into cytoplasm, and translated into protein by ribosomes

Question 7

Endocrine Glands throughout the body

H
T(PT)
A
P
P
OT

Answer 7

Hypothalamus - pituitary: main center for homeostatic regulation of the body

Thyroid gland: thyroid hormone influences metabolism and growth; calcitonin with clinical affects of Ca2+ regulation
– Parathyroid gland: PTH involved in Ca2+ regulation

Adrenal glands: cortical hormones influence energy metabolism and osmotic balance; medullary hormones interact with sympathetic nervous system

Pancreas

• • exocrine for digestive enzymes
• • endocrine for insulin and glucagon to regulate blood sugar level

Pineal gland: melatonin with diverse effects

Ovaries and Testes: synthesize steroidal sex hormones

Question 8

Endocrine Glands in the human brain

• hypo
• post lobe (3)
• ant lobe (2)

Answer 8

Hypothalamus: main homeostatic control center; monitors physiological status of body; affects changes by controlling release of hormones from pituitary glands

POSTERIOR lobe of pituitary: aka neurohypophysis; derived from neural tissue;

1. oxytocin: milk creation in mammals and uterine contractions during childbirth
2. vasopressin: influences polygamy / monogamy desire; affects water conservation
3. ADH: reduces urine volume at collecting duct in kidney

ANTERIOR: aka adenohyophysis; derived from epithalial tissue; location of third portal system
– THREE LEVEL ENDOCRINE AXES: tropic, therefore target and regulate other endocrine glands»_space;> 1. GH – 2. LH, FSH – 3. ACH
– PATHWAY: hypothalamus secretes releasing hormones
into portal system > bind to receptors of hormone producing cells of anterior > anterior hormones released into capillary bed > enter general circulation and affect target organs