REGULATION Endocrine Nervous Systems AP Biology Homeostasis Homeostasis

REGULATION: Endocrine & Nervous Systems AP Biology

Homeostasis § Homeostasis u maintaining internal balance in the body § organism must keep internal conditions stable even if environment changes § also called “dynamic equilibrium” u example: body temperature § humans: w too cold = shiver w too warm = sweat § lizard: w too cold = bask in sun w too warm = hide in shade Regents Biology

Regulation § How we maintain homeostasis u nervous system § nerve signals control body functions u endocrine system § Hormones secreted from glands § chemical signals control body functions Regents Biology

Nervous System Controlling Body Temperature Negative Feedback nerve signals brain sweat high body temperature low brain constricts surface shiver blood vessels Regents Biology nerve signals dilates surface blood vessels

Nervous System cerebrum cerebellum spinal cord § Central nervous system u brain & spinal chord § Peripheral nervous system nerves from senses u nerves to muscles u cervical nerves thoracic nerves lumbar nerves femoral nerve sciatic nerve tibial nerve Regents Biology 2003 -2004

Nervous system cells § Neuron signal u direction a nerve cell dendrites cell body § Structure fits function many entry points for signal u one path out u transmits signal u axon signal direction myelin sheath Regents Biology dendrite cell body axon synaptic terminal synapse

Myelin coating signal direction § Axon coated with insulation made of Schwann cells u speeds signal § signal hops from node to node u 330 mph vs. 11 mph myelin coating Multiple Sclerosis Regents Biology § immune system (T cells) attacks myelin coating 2003 -2004 § loss of signal

Synapse Junction between nerve cells u u 1 st cell releases chemical to trigger next cell where drugs affect nervous system synapse Regents Biology

Types of neurons sensory neuron (from senses) interneuron (brain & spinal chord) Regents Biology motor neuron (to muscle)

Transmission of a nerve signal § Neuron protein channels are set up u once first one is opened, the rest open in succession u § all or nothing response a “wave” action travels along neuron u have to re-set channels so neuron can react again u Regents Biology

Cells have voltage! § Opposite charges on opposite sides of cell membrane u membrane is polarized § negative inside; positive outside § charge gradient § stored energy (like a battery) + + + + – – – – – – – + + + + Regents Biology

How does a nerve impulse travel? § Stimulus: nerve is stimulated u reaches threshold potential § open Na+ channels in cell membrane § Na+ ions diffuse into cell u charges reverse at that point on neuron § positive inside; negative outside § cell becomes depolarized – + + + + – – – – Na+ + – – – – + + + + Regents Biology

How does a nerve impulse travel? § Wave: nerve impulse travels down neuron u u u Gate + change in charge opens + – + next Na gates down the line § “voltage-gated” channels channel Na+ ions continue to diffuse into cell closed “wave” moves down neuron = action potential + channel open – – – + + + + – – – Na+ + – – – – + + + Regents Biologywave

How does a nerve impulse travel? § Re-set: 2 nd wave travels down neuron u K+ channels open § K+ channels open up more slowly than Na+ channels u u K+ ions diffuse out of cell charges reverse back at that point § negative inside; positive outside K+ + – – + + + + + – – – – – Na+ – + + – – – – – + + + + + Regents Biologywave

How does a nerve impulse travel? § Combined waves travel down neuron u u wave of opening ion channels moves down neuron signal moves in one direction § flow of K+ out of cell stops activation of Na+ channels in wrong direction K+ + – – + + + + – – – – Na+ – – – + + – – – – + + + + Regents Biologywave

How does the nerve re-set itself? § Sodium-Potassium pump u active transport protein in membrane § requires ATP 3 Na+ pumped out u 2 K+ pumped in u re-sets charge across membrane u Regents Biology ATP

Chemical synapse axon terminal § Events at synapse action potential u synaptic vesicles synapse u u Ca++ receptor protein u neurotransmitter acetylcholine (ACh) muscle cell (fiber) Regents Biology action potential depolarizes membrane neurotransmitter vesicles fuse with membrane release neurotransmitter to synapse diffusion neurotransmitter binds with protein receptor u neurotransmitter degraded or reabsorbed

Neurotransmitters § Acetylcholine u transmit signal to skeletal muscle § Epinephrine (adrenaline) u fight-or-flight response § Dopamine u u widespread in brain affects sleep, mood, attention & learning lack of dopamine in brain associated with Parkinson’s disease excessive dopamine linked to schizophrenia § Serotonin widespread in brain u affects sleep, mood, attention & learning Regents Biology u

Primitive brain § The “lower brain” medulla oblongata u pons u cerebellum u § Functions u basic body functions § breathing, heart, digestion, swallowing, vomiting homeostasis u coordination of movement u Regents Biology 2003 -2004

Higher brain § Cerebrum 2 hemispheres u left = right side of body u right = left side of body u § Corpus callosum u connection between 2 hemispheres Regents Biology 2003 -2004

Division of Brain Function § Left hemisphere u u u “logic side” language, math, logic operations, vision & hearing details fine motor control § Right hemisphere u u “creative side” pattern recognition, spatial relationships, non-verbal ideas, emotions, multi-tasking Regents Biology 2003 -2004

Cerebrum specialization § Regions specialized for different functions § Lobes u frontal parietal § speech, control of emotions u temporal § smell, hearing u occipital § vision u parietal § speech, taste reading temporal Regents Biology occipital 2003 -2004

Simplest Nerve Circuit § Reflex, or automatic response rapid response § automated u signal only goes to spinal cord § no higher level processing u advantage § essential actions § don’t need to think or make decisions about § blinking § balance § pupil dilation § startle u Regents Biology

Endocrine System Hormones & Homeostasis AP Biology

Hormones § Why are hormones needed? chemical messages from one body part to cells in other parts of body u communication needed to coordinate whole body u maintaining homeostasis u Regents Biology growth hormones

Endocrine System § Endocrine system releases hormones u glands which secrete (release) chemical signals into blood § chemicals cause changes in other parts of body w growth hormones w sex hormones w response hormones w metabolism hormones w and more…. Regents Biology

Responding to hormones § Lock and key system u hormone fits receptor on “target” cell target cell secreting cell Regents Biology can’t read signal nontarget cells can’t read signal

Glands § Pituitary u many hormones: master gland § Thyroid u thyroxine § Adrenal u adrenaline § Pancreas u insulin, glucagon § Ovary u estrogen § Testes u testosterone Regents Biology

Negative Feedback § Response to changed body condition u if body is high or low from normal level § signal tells body to make changes that will bring body back to normal level u once body is back to normal level, signal is turned off gland hormone 1 lowers body condition high Regents Biology specific body condition

Positive Feedback § Response to changed body condition u u Causes an increase in product from normal level § signal tells body to continue to produce more of the product § enhances the response Once the changed body condition returns to normal, the synthesis of product returns to normal Regents Biology

Pituitary gland hormones GH § growth hormone u ADH § Water reabsorption in kidneys Sex & reproductive hormones u FSH § follicle stimulating hormone § stimulates egg & sperm production u LH § luteinizing hormone § stimulates ovaries & testes § prepares uterus for fertilized egg hormones u oxytocin § stimulates childbirth contractions u § Regents Biology hormones

Thyroid Gland § Thyroxine Stimulates metabolism u Influences development and maturation u § Hyperthyroidism, excessive secretion of thyroid hormones u Can cause Graves’ disease in humans Regents Biology

Insulin and Glucagon: Control of Blood Glucose § Two types of cells in the pancreas u Two antagonistic hormones that help maintain glucose homeostasis and § Islets of Langerhans w Glucagon Raises blood glucose w Insulin n Lowers blood glucose n Regents Biology

Endocrine System Control Regulation of Blood Sugar insulin liver stores sugar body cells take up sugar from blood pancreas Negative Feedback high liver blood sugar level (90 mg/100 ml) low triggers hunger Regents Biology liver releases sugar liver pancreas glucagon reduces appetite

Diabetes Mellitus § Diabetes mellitus, perhaps the best-known endocrine disorder Is caused by a deficiency of insulin or a decreased response to insulin in target tissues u Is marked by elevated blood glucose levels u Regents Biology

§ Type I diabetes mellitus (insulin-dependent diabetes) u Is an autoimmune disorder in which the immune system destroys the beta cells of the pancreas § Type II diabetes mellitus (non-insulindependent diabetes) u Is characterized either by a deficiency of insulin or, more commonly, by reduced responsiveness of target cells due to some change in insulin receptors Regents Biology

Adrenal Glands § Adrenal Medualla u Epinepherine u Stress activated u Fight or flight response http: //learn. genetics. utah. edu/co ntent/cells/cellcom/ Regents Biology

Gonads § Testosterone u u from testes sperm production & secondary sexual characteristics § Estrogen u u from ovaries egg production, preparing uterus for fertilized egg & secondary sexual characteristics Regents Biology

Body Regulation § Nervous system & Endocrine system work together u hypothalamus § “master nerve control center” § receives information from nerves around body about internal conditions u communicates with pituitary gland § “master gland” § releases many hormones w sexual development, growth, Regents Biology milk production, pain-relief hormones

Regulation by chemical messengers § Neurotransmitters released by neurons § Hormones release by endocrine glands endocrine gland neurotransmitter axon hormone carried by blood receptor proteins Regents Biology receptor proteins target cell