Mechanisms of Homeostasis Homeostasis is like your homes

Mechanisms of Homeostasis

Homeostasis is like your home’s thermostat Thermostat’s set point is 75ºF heat Inside temperature = 72ºF 75ºF 74ºF 73ºF

• Defined: Process where the body maintains a constant internal environment • Importance: Internal reactions & enzymes work best in specific conditions • Control systems adjust to internal/external changes • Changes controlled: p. H, temp, fluids

Control Systems • Sensors (aka: receptors) – Gather information about the body and environment – Ex: skin senses pressure • Communication Center – Messages sent throughout the body to respond – Ex: Impulse travel through your nerves • Control Center – Receives information from the sensors – Ex: Brain interprets the impulse • Targets – Body part that changes its activity – Ex: Muscles in foot stretch/contract abruptly !*%!? %&#

Negative Feedback Loops • Regulates most of the body • Reverses any change that moves conditions from a set point – Ex: if your temp drops…you will shiver to reverse that 96. 8 97. 2 97. 5 97. 7 98. 1 98. 4 98. 6

Negative Feedback Loops • Regulates most of the body • Reverses any change that moves conditions from a set point – Ex: if your temp drops…you will shiver to reverse that – Ex: If your temp rises…you will sweat to reverse that 100. 1 99. 7 99. 5 99. 2 98. 8 98. 6

Negative Feedback Loop: Cold Response

Negative Feedback Loop: Breathing

Positive Feedback Loop • Increases the changes away from set points • Important when rapid change is needed • Ex: Pregnancy contractions – Uterus contractions begin slowly – Oxytocin released to speed up the contractions Negative Ask yourself… feedback would reverse and stop So how will the body respond to the If the this contractions. was negative feedback, if the feedback? contractions what would contractions if it’s. But positive happen next? stopped, would the baby be delivered?

Working Together • Thermoregulation: Maintenance of body temperature – Skin: sensors detect cold – Nervous system: electrical impulse sent to brain – Endocrine system: releases hormones into blood stream – Muscles: Hormones cause shivering

Homeostasis disruption • Some disruptions temporary – Infections, fever, sore throats, muscle soreness • Some disruptions too great for your body to control – Frost bite: Sensors are destroyed – Paralysis: Messages from brain doesn’t reach target Beck Weathers, thought to be dead, survived a night exposed to Mt. Everest cold.

Diabetes & Homeostasis glucose glucose glucose glucose insulin glucose • Normally – Glucose in blood rises after meals – Pancreas releases insulin – Cells remove the glucose • Type 1 – Immune system destroys pancreas cells – Pancreas unable to make insulin – Blood p. H decreases as glucose builds up • Type 2 – Pancreas does not make enough insulin – Blood p. H decreases as glucose builds up

Kobe Kuiz 1) 2) 3) 4) 5) Define homeostasis. Name and describe the four parts of the “control system. ” What is negative feedback? What is positive feedback? Is the following example positive or negative feedback? During heavy exercise your body loses water when you sweat. As a result of water loss, your body redirects the remaining water inside your body to vital parts of your body to replenish these vital organs. 6) What is diabetes? 7) How does Type I and Type II diabetes differ?