BIOL 1030H Lecture Notes - Lecture 2: Homeostasis, Threshold Potential, Action Potential
13 May 2018
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Department
Course
Professor
Homeostasis and Animal Nervous System
Environmental changes
Animals must deal with constantly changing environments.
• External
• Endogenous (self-imposed)
The organism must maintain a suitable internal environment
Homeostasis
What is homeostasis?
“The active regulation and maintenance, in animals, organs, or cells, of a stable physiological
state in the face of changing environmental conditions” Morris et al (2016)
What is so stable about homeostasis?
Skin temperature, breathing rate, heart rate, sweating, and heat production all vary
Not all systems are variable
Some systems change greatly in order to buffer others from damaging change.
Least variable systems are in the “core.”
Homeostasis is widespread
Nearly universal in all living things.
Allows animals to invade “physiologically unfriendly” environments
Homeostasis requires physiological control systems
Essential components
1. Sensors (touch receptors)
2. Integrator/control centre (brain)
3. Effectors (muscles, sweat glands)
Tied together in negative feedback loop
Environmental change
• Maintenance of steady state is complex in an unchanging environment
– Heat, high altitude (low oxygen), cold temperatures
• When the environment is continuously changing it gets really complicated!
Organisms fall into two categories when
responding to environmental change:
Document Summary
Animals must deal with constantly changing environments: external, endogenous (self-imposed) The organism must maintain a suitable internal environment. The active regulation and maintenance, in animals, organs, or cells, of a stable physiological state in the face of changing environmental conditions morris et al (2016) Skin temperature, breathing rate, heart rate, sweating, and heat production all vary. Some systems change greatly in order to buffer others from damaging change. Essential components: sensors (touch receptors, integrator/control centre (brain, effectors (muscles, sweat glands) Environmental change: maintenance of steady state is complex in an unchanging environment. Heat, high altitude (low oxygen), cold temperatures: when the environment is continuously changing it gets really complicated! Organisms fall into two categories when responding to environmental change: conformers (cannot maintain homeostasis, regulators (maintain homeostasis) In animals, homeostasis is maintained by the endocrine and nervous systems: endocrine system. Releases hormones: a chemical substance released into bloodstream, which circulates throughout the body, and exerts influence on distant cells.
