Presentation on theme: "What would happen to me if I stuck my head in cold water??"— Presentation transcript:
What would happen to me if I stuck my head in cold water??
Mammalian Dive Reflex Homeostatic Responses During: Vasoconstriction in extremities to conserve heat Decrease in heart rate Blood flow returning to heart is increased Kidneys release urine in effort to counter high blood volume in core
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
Homeostatic Responses After: Vasodilation in extremities (face) to bring heat and oxygen back Heart rate increases and re-sets rhythm What is a homeostatic response?? Homeostasis – process by which a constant internal environment is maintained despite changes in the external environment
Poor old me, trying to get back in shape
Dynamic Equilibrium – condition that remains stable within fluctuating limits (homeostasis is a dynamic equilibrium) All homeostatic control systems have: – Monitors and sensors – Coordinating centre – Regulator and effectors
Hire-wire Artist Model Variable: position of body Setpoint: directly over the wire Monitors and Sensors: nerve receptors (eyes, inner ears, muscle stretch receptors, etc.) Regulator: brain Effectors: skeletal muscles High-wire artist uses negative feedback to maintain relatively constant position on wire.
Heat and cold receptors, rather than detecting specific temperatures as does like a thermostat, are adapted to signal CHANGES in environmental temperatures Extension #1: Using this information, explain why you might feel a chill when you step out of a warm shower even though room temperature is comfortable Extension #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
Negative Feedback Systems (common) Bring system back to acceptable range Prevents small internal adjustments from getting out of hand Eg. When body temperature continues to drop, body begins to shiver to reverse the temperature (bring back to norm) Blood glucose
Positive Feedback Systems (uncommon) Amplify a small change, moves away from equilibrium Allows a discrete event to happen rapidly Eg. Lactation – suckling baby stimulates production of oxytocin, in turns causes contraction of milk duct muscles, causing milk flow… and flow of milk increases suckling
A reflex A 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.
We will be examining 3 systems that help maintain homeostasis The excretory system The nervous system The endocrine system
Excretory System Why do we really pee??? Average person consumes more protein than necessary While most are converted to carbohydrates, the leftover nitrogen must be eliminated Process is called deamination which produces urea - N 2 COH 2 Kidneys play a crucial in: Removing waste Balancing blood pH Maintaining water balance
Excretory System Bladder Sphincter at base allows storage of urine When 200 ml is collected, bladder stretches which sends nerve message to the brain 600 ml or more – bladder relaxes and you urinate! Urine is voided via the urethra
Neurons: Cells which can transmit nerve impulses in the form of electrochemical messages The axon sends a wave of depolarization along its length The wave of depolarization is primarily the movement of Na + and K + ions across the axon’s membrane The nervous system
Endocrine hormones are produced in glands and are secreted into the bloodstream find target cells The endocrine system is the system of glands, each of which secretes a type of hormone directly into the bloodstream to regulate the body. Endocrine system