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Systems of Communication and Regulation Cells of the body all interact with one another in order to maintain homeostasis Nervous system Conveys high-speed electrical signals along specialized cells called neurons Enables body to adjust quickly to changes in its environment Endocrine system Made up of endocrine glands Glands secretes hormones that coordinate slower but longer-acting responses to stimuli

Nervous System Conveys messages: From brain to spinal cord to organs From organs to spinal cord to brain

Neuron Synapse – connection between two neutrons OR between a neuron and another type of cell

Glands of the Endocrine System Secrete (release) hormones Hypothalamus Pineal gland Pituitary gland Thyroid gland Parathyroid glands Adrenal glands Pancreas Ovary (female) Testis (male)

Glands endocrine glands – organs producing molecules delivered by blood stream exocrine glands – organs producing molecules delivered by ducts (cellular tubes) salivary glands sweat glands Pancreas is both endocrine and exocrine Secretes hormones (endocrine) Produces digestive enzymes (exocrine)

Endocrine Hormones Hormone Is a molecule that is secreted (released) into the circulatory system (blood) communicates regulatory messages (signals) within the body to increase/decrease processes Hormones may reach all parts of the body But only certain types of cells, target cells, are equipped to respond PathwayExample Stimulus Low blood glucose Receptor protein Pancreas secretes glucagon ( ) Endocrine cell Blood vessel Liver Target effectors Response Pathway Example Stimulus Suckling Sensory neuron Hypothalamus/ posterior pituitary Neurosecretory cell Blood vessel Posterior pituitary secretes oxytocin ( ) Target effectors Smooth muscle in breast Response Milk release Pathway Example Stimulus Hypothalamic neurohormone released in response to neural and hormonal signals Sensory neuron Hypothalamus secretes prolactin- releasing hormone ( ) Neurosecretory cell Blood vessel Anterior pituitary secretes prolactin ( ) Endocrine cell Blood vessel Target effectors Response Mammary glands Milk production (c) Simple neuroendocrine pathway (b) Simple neurohormone pathway (a) Simple endocrine pathway Hypothalamus Glycogen breakdown, glucose release into blood

Insect metamorphosis is regulated by hormones

Endocrine Hormone Pathway All regulatory pathways include three steps: 1. Stimulus 2. Target Effectors (Cell/Tissue/Organ) 3. Response PathwayExample Stimulus Low blood glucose Receptor protein Pancreas secretes glucagon ( ) Endocrine cell Blood vessel Liver Target effectors Response Pathway Example Stimulus Suckling Sensory neuron Hypothalamus/ posterior pituitary Neurosecretory cell Blood vessel Posterior pituitary secretes oxytocin ( ) Target effectors Smooth muscle in breast Response Milk release Pathway Example Stimulus Hypothalamic neurohormone released in response to neural and hormonal signals Sensory neuron Hypothalamus secretes prolactin- releasing hormone ( ) Neurosecretory cell Blood vessel Anterior pituitary secretes prolactin ( ) Endocrine cell Blood vessel Target effectors Response Mammary glands Milk production (c) Simple neuroendocrine pathway (b) Simple neurohormone pathway (a) Simple endocrine pathway Hypothalamus Glycogen breakdown, glucose release into blood

Hormone Discovery Joseph van Mering & Oscar Minkowski removed pancreas from dogs rapid weight loss fatigued ants gathered around urine CONCLUSION: Chemical messenger, produced by the pancreas, is responsible for regulating body sugars

How do hormones signal cells? hormones are specific to target cells How do they know where to go? target cells have protein receptors (lock and key) If a cell does not have receptors that fit a specific hormone, the hormone will have no effect!

What happens when a hormone binds to its receptor? Signal Transduction Pathway A series of Phosphorylations (activation of enzymes) 1. specific responses in the cytoplasm 2. change in gene expression Signal Transduction Pathway TARGET CELL

Example: Puberty Testosterone from testes (males) responsible for the development of “secondary male sexual characteristics” in specific tissues, for example: Development of facial and body hair Growth of larynx (deepens voice) These are essentially changes in gene expression (usually transcription)

Hormone Types 1. steroid hormones 2. protein hormones

Steroid Hormones made from cholesterol – lipid compound not soluble in water (hydrophobic) E.g. male and female sex hormones and cortisol 1. diffuse from cell of origin (through membranes) 2. diffuse into target cell 3. often moves into nucleus to affect transcription SECRETORY CELL Hormone molecule VIA BLOOD TARGET CELL Signal receptor Signal transduction and response DNA mRNA NUCLEUS Synthesis of specific proteins (b) Receptor in cell nucleus

Protein Hormones short peptide sequences water soluble (hydrophillic) E.g. Insulin and Growth Hormone 1. transported from cell of origin (secretory vacuoles) 2. attach to surface receptors of target cells 3. activates enzymes to make other internal signals SECRETORY CELL Hormone molecule VIA BLOOD Signal receptor TARGET CELL Signal transduction pathway Cytoplasmic response Nuclear response NUCLEUS DNA OR (a) Receptor in plasma membrane

Protein Hormone Action R H ATP cyclic AMP + PPi other enzymes Cyclic AMP

Pituitary Gland

overlooks operation of all other glands – “Master Gland” Two lobes: posterior lobe – stores and releases hormones produced in hypothalamus; released upon signal anterior lobe – produces own hormones; released upon hypothalamus signal

Pituitary Gland: Closer Look Produces and stores hormones Interaction of Endocrine System and Nervous System Hypothalamus stimulates the release of hormones in the posterior pituitary gland by way of nerves E.g. secretion of ADH

Posterior Pituitary Hormones

Anterior Pituitary Hormones

How do hormones travel from the hypothalamus to the pituitary gland? Neurosecretory Cells Hormones are secreted from nerve cells of hypothalamus via vesicles and exocytosis Transported in the blood to the pituitary gland

Hypothalamus & Pituitary Gland Animation - Pituitary and Hypothalamus.mov McGraw Hill - Hormonal Communication.swf

PathwayExample Stimulus Low blood glucose Receptor protein Pancreas secretes glucagon ( ) Endocrine cell Blood vessel Liver Target effectors Response Pathway Example Stimulus Suckling Sensory neuron Hypothalamus/ posterior pituitary Neurosecretory cell Blood vessel Posterior pituitary secretes oxytocin ( ) Target effectors Smooth muscle in breast Response Milk release Pathway Example Stimulus Hypothalamic neurohormone released in response to neural and hormonal signals Sensory neuron Hypothalamus secretes prolactin- releasing hormone ( ) Neurosecretory cell Blood vessel Anterior pituitary secretes prolactin ( ) Endocrine cell Blood vessel Target effectors Response Mammary glands Milk production (c) Simple neuroendocrine pathway (b) Simple neurohormone pathway (a) Simple endocrine pathway Hypothalamus Glycogen breakdown, glucose release into blood

Online Resources Bozeman Biology – Endocrine System McGraw Hill – Steroid Hormones hill.com/olcweb/cgi/pluginpop.cgi?it=swf::535::535::/sites/dl/free/ /120109/bio46. swf::Mechanism%20of%20Steroid%20Hormone%20Action McGraw Hill – Lipid Soluble Hormones McGraw Hill – Hormone Communication hill.com/sites/ /student_view0/chapter20/animation__hormonal_communicati on.html McGraw Hill – Blood Sugar Regulation in Diabetics hill.com/sites/ /student_view0/chapter20/animation__blood_sugar_regulation_ in_diabetics.html