Presentation on theme: "What would happen to me if I stuck my head in cold water??"— Presentation transcript:
1 What would happen to me if I stuck my head in cold water??
2 Mammalian Dive Reflex Homeostatic Responses During: Vasoconstriction in extremities to conserve heatDecrease in heart rateBlood flow returning to heart is increasedKidneys release urine in effort to counter high blood volume in core
3 WHY ??Optimizes respiration to allow staying underwater for extended periods of time.It is exhibited strongly in aquatic mammals (seals, otters, dolphins, etc.), but exists in a weaker version in other mammals, including humans
4 What is a homeostatic response?? Homeostatic Responses After:Vasodilation in extremities (face) to bring heat and oxygen backHeart rate increases and re-sets rhythmWhat is a homeostatic response??Homeostasis – process by which a constant internal environment is maintained despite changes in the external environment
6 All homeostatic control systems have: Dynamic Equilibrium – condition that remains stable within fluctuating limits (homeostasis is a dynamic equilibrium)All homeostatic control systems have:Monitors and sensorsCoordinating centreRegulator and effectors
7 Hire-wire Artist Model Variable:position of bodySetpoint:directly over the wireMonitors and Sensors:nerve receptors (eyes, inner ears, muscle stretch receptors, etc.)Regulator:brainEffectors:skeletal muscles High-wire artist uses negativefeedback to maintain relativelyconstant position on wire.
8 signal CHANGES in environmental temperatures Heat and cold receptors, rather than detecting specific temperatures as does like a thermostat, are adapted tosignal CHANGES in environmental temperaturesExtension #1: Using this information, explain why you might feel a chill when you step out of a warm shower even though room temperature is comfortableExtension #2: Using this information, explain why when a frog is placed in a beaker of water above 40°C, the frog will leap out immediately, but when the frog is placed in room-temperature water and the temperature is slowly elevated, the frog does not leap out
9 Negative Feedback Systems (common) Bring system back to acceptable rangePrevents small internal adjustments from getting out of handEg. When body temperature continues to drop, body begins to shiver to reverse the temperature (bring back to norm)Blood glucose
10 Positive Feedback Systems (uncommon) Amplify a small change, moves away from equilibriumAllows a discrete event to happen rapidlyEg. Lactation – suckling baby stimulates production of oxytocin, in turns causes contraction of milk duct muscles, causing milk flow… and flow of milk increases suckling
11 A reflexA specific, involuntary, unpremeditated response to a particular stimulus.A stimulus being a detectable change in the internal or external environment. The pathway meditating a reflex is called a reflex arc.
12 We will be examining 3 systems that help maintain homeostasis The excretory systemThe nervous systemThe endocrine system
13 Excretory System Why do we really pee??? Average person consumes more protein than necessaryWhile most are converted to carbohydrates, the leftover nitrogen must be eliminatedProcess is called deamination which produces urea - N2COH2Kidneys play a crucial in:Removing wasteBalancing blood pHMaintaining water balance
14 Excretory SystemBladderSphincter at base allows storage of urineWhen 200 ml is collected, bladder stretches which sends nerve message to the brain600 ml or more – bladder relaxes and you urinate!Urine is voided via the urethra
15 The nervous systemNeurons: Cells which can transmit nerve impulses in the form of electrochemical messagesThe axon sends a wave of depolarization along its lengthThe wave of depolarization is primarily the movement of Na+ and K+ ions across the axon’s membrane
16 Endocrine systemThe endocrine system is the system of glands, each of which secretes a type of hormone directly into the bloodstream to regulate the body.Endocrine hormones are produced in glands and are secreted into the bloodstream find target cells