Test 1 Outline: BIO 203Lecture 1:- Homeostasis, a control systemo Physiological regulation – maintaining “similar conditions” in the internal environmento Cannon’s Postulates (4): 1) The nervous system has a role in preserving the “fitness” of the internal environment- Fitness: conditions compatible with normal function- Regulated variables (parameters):o body temperatureo blood pressureo blood volumeo blood osmolality o Others… 2) Some systems of the body are under tonic control (tone)- The response is always on, but the strength can be increased or decreasedo radio: it is always on, but you can turn the volume up or down 3) Some systems of the body are under antagonistic control- If a system is not under tonic control – it is usually under antagonistic control. Hormones or the nervous system.o Nervous system: sympathetic and parasympathetic divisions often have opposing effects.  Heart rate: one slows, one increaseso Example: insulin and glucagon  4) One chemical signal can have different effects in different tissues- Homeostatic agents that are antagonistic in one region could be cooperative in another region of the body- Caused by receptorso Alpha and beta2 receptors act differently in response to epinephrine. One causes blood vessels to constrict, while the other causes dilation. o Homeostasis is NOT the same as equilibrium  Equilibrium implies that there is no reaction occurring The body is constantly undergoing reactionso When an internal or external change occurs, homeostasis is lost The organism then attempts to compensate Compensation is a success: homeostasis restored, wellness Compensation is a failure: homeostasis is not returned, illness or disease- Feedback Systemso Elements: Sensor- Monitors conditions- Can detect stimuli – a change in the condition Integrating center- Compares the current state to a setpoint Threshold- Point that needs to be reached before triggering a response Effector- Performs an action Response- Resulting outputo Positive Feedback  Response is in the same direction as the change- Reinforces the change- Produces large, rapid changes  Less common Examples:- Trail of gunpowder. Rapid signal that keeps going until it explodes. Self-limiting- First portion of the action potential. Sodium causes it to go on and on. Potassium corrects it.- During childbirth: as baby pushes against the cervix, oxytosin is released, causing contraction wave. Continues until delivery stops the cycle – there is no more pressure on the cervix. o Negative Feedback Response is opposite to the change- If too cold, machine raises the temperature- If too hot, the machine lowers the temperature Because it opposes the change, it returns it to the setpoint  Homeostatic- Operates in a narrow range- Does not compensate for small changes- Present at cellular and organ levels- Regulation:o If you have a lot of the “rate limiting” ingrediento If you have a lot of the desired producto Allostatic Alter the range of function- Altered setpoint New conditions to support the situationo Feedforward Regulation: Prediction Not a closed loop (feedback) system Involves learning- Example: Pavlov’s dogs- Prediction of an event (feeding) Helps to smooth transitions  Physiological Example:- Before a race, your heart rate is up, breathing is increased. Preparing forthe gun shot. This makes a smoother transition into sprinting.o Properties Delays are detectable - Dependent upon anatomy and processing- Example: even a simple reflex takes time if the brain is involved Gain – expresses the intensity or magnitude of the effector action  Oscillation – may often be observed as the feedback system functions- Especially noticeable with long delay and high gain - Fluctuates around an acceptable setpoint Not everything is controlled by a feedback or feedforward systemLecture 2:- Endocrine vs. Paracrineo Endocrine Regulation releases a chemical (hormone) into the blood, and often works at a distance from the glando Paracrine Regulation is local. Uses chemical signaling among neighboring cells Transportation via blood is not required Takes longer because the signal must travel Example: nervous systemo Autocrine Cell self-regulates Have receptors for their own signals- Neural vs. Hormonalo Some regulation is purely through the nervous system Goes to skeletal muscles, leads to a twitch Discrete. Motor neuron, goes to a skeletal muscle, to some of the fibers within that muscle Does not activate neighbors Very quick o Some regulation is purely endocrine Via hormones carried through the blood Insulin release. Pancreas stimulates itself – beta cells serve as glucose sensors.- When glucose levels increase, insulin is releasedo Some regulation is hybrid: neurohormonal  Nervous system has sensors, integration for hormone release and actions on distant targets Multiple hormones may be involved  Most hormones (thyroid, testosterone, etc) are driven by signals that come from the central nervous system of the brain- Regulatory Componentso Sensors Often local Can be long range: hearing, visiono Effectors Movement Includes glands and secretionso Integrating Regions bring in sensory info and issue commands to effectors May be large and circuitry, such as the nervous system, or within single cells- Reflexo Smallest unit of regulatory function o Components: Sensory Integrating Effector functionso Can study by looking at animals that have much simpler nervous systems- Nervous systemo Specializes in regulationo The most complex system Billions of cells Diverse cell types and shapes Various functions Complex biochemistry and regulation Emergent functionso The ability to measure action potentials – HUGE o Phineas Gage – first time the brain and CNS could be studiedo Cells within the nervous system Neuron- Cell body is the enlarged region surrounding the nucleus- Variable numbers of extensions reach outward from the cell body- Neuron sizes widely varieso Large neurons can interconnect distant structureso Small neurons can from “local circuit” connections- Polarized function: one region specializes in biochemistry output, another region is input, another region are carriers- Structure: branches that extend all throughout the body Neuron Cell Body- Nucleus – large and paleo Has a highly