ENDOCRINE VS. NERVOUS SYSTEM

Function?  Coordinate body functions (Both)  Often work together

Method?  Use chemical messengers  Nervous system: neurotransmitters  Endocrine: hormones

Hormones- 2 classes  1. Amino-Acid-derived Hormones  Water-soluble  2. Steroid Hormones  Hydrophobic

Cell Signaling follows 3 Steps 1. Reception  A signal binds to a receptor on the receiving cell 2. Transduction  The receptor binding causes a change (sometimes a series of changes) on the inside of the cell. 3. Response  This will result some sort of response by the receiving cell. Passing on a signal, releasing a protein, begin transcription, etc.

AA vs. Steroid Hormones

Target? Both deal with receptor specificity!  Nervous: Other adjacent neurons, effectors (glands, muscles)  Specific! Very local target, w/ specific NT receptors  Endocrine: Cells throughout the body  Global release of message, but specific response  Like a radio broadcast, it requires a receiver (receptor) to get the message

Speed?  Nervous: Fast! (meters per second)  Endocrine: Slow(er), more prolonged  May affect same cell, adjacent cell, cell on other side of body

Example: simple endocrine pathway & negative feedback

Example: simple neurohormone pathway & positive feedback

Nervous & Endocrine systems linked  Hypothalamus = “master nerve control center”  nervous system  receives information from nerves around body about internal conditions  releasing hormones: regulates release of hormones from pituitary  Pituitary gland = “master gland”  endocrine system  secretes broad range of “tropic” hormones regulating other glands in body hypothalamus pituitary posterior anterior

Thyroid gland hypothalamus anterior pituitary gonadotropic hormones: follicle- stimulating hormone (FSH) & luteinizing hormone (LH) Mammary glands in mammals Muscles of uterus Kidney tubules posterior pituitary thyroid-stimulating hormone (TSH) antidiuretic hormone (ADH) Adrenal cortex Bone and muscle Testes Ovaries Melanocyte in amphibian adrenocorticotropic hormone (ACTH) melanocyte-stimulating hormone (MSH) oxytocin prolactin (PRL) growth hormone (GH) tropic hormones = target endocrine glands

Regulation of Blood Calcium blood calcium level (10 mg/100mL) calcitonin parathyroid hormone (PTH)  Ca ++ uptake in intestines high low  kidney reabsorption of Ca ++ bones release Ca ++  kidney reabsorption of Ca ++ Ca ++ deposited in bones activated Vitamin D thyroid parathyroid

liver pancreas liver Regulation of Blood Sugar blood sugar level (90mg/100ml) insulin body cells take up sugar from blood liver stores glycogen reduces appetite glucagon pancreas liver releases glucose triggers hunger high low beta cells alpha cells

Pathways with Friends