Body Structure, Function, and Regulation
Classified in Biology
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Basic Concepts
Anatomy - structure of the body
Physiology - function of each organ
Characteristics of Living Things
- Movement - motion where the organism will go from one place to the other
- Responsiveness - how any organism reacts
- Growth - an organism's ability to get bigger
- Reproduction - ability of an organism to produce offspring
- Respiration - the ability of an organism to gain oxygen from food
- Digestion - ability of an organism to break down food
- Absorption - ability of an organism to take in nutrients
- Circulation - ability of materials to go through the body
- Assimilation - food is taken in and changed to something essential
- Excretion - ability of our bodies to remove waste
Homeostasis and Regulation
Homeostasis - stability of a constant internal environment
There's this girl running a marathon, and she drank so much water she couldn’t run the rest of the race and she gained weight. Doctors observed her and said she had hyponatremia (too low sodium/salt concentration and too much water in body that isn’t being disposed of).
Water intoxication is extreme hyponatremia that could lead to a coma or even death.
Feedback Mechanisms
Feedback mechanisms maintain homeostasis. They detect when something in your body is off and fix it.
Receptor - Special cell that receives information.
Effector - Muscle or gland that reacts to the signal.
Negative Feedback
Negative feedback maintains homeostasis through receptors and a set point, helping retain normal environmental activities.
Insulin and Glucagon Example
Insulin - When blood sugar rises, receptors in the body sense a change and the pancreas releases insulin, which regulates the glucose level. This is negative because insulin stops pumping when the blood sugar goes down.
Glucagon - When there’s low blood sugar, the pancreas releases glucagon, which regulates the blood level. This is negative because once the blood sugar is regulated, it stops producing glucagon.
Thermostat Analogy
A good example of a negative feedback mechanism is a home thermostat (heating system). The thermostat contains the receptor (thermometer) and control center. If the heating system is set at 70 degrees Fahrenheit, the heat (effector) is turned on if the temperature drops below 70 degrees Fahrenheit. After the heater heats the house to 70 degrees Fahrenheit, it shuts off, effectively maintaining the ideal temperature.
Positive Feedback
Positive feedback maintains homeostasis by measuring the occurrence of events.
Examples include when someone is giving birth or nursing a baby:
- Giving birth - there’s a message sent through the body to “help” the mother push.
- Nursing - sensation produces hormones.
Vital Signs
Vital signs - the picture of how a person is doing.
This means temperature, blood pressure, heart rate, and pulse.
Vital signs relate to homeostasis because homeostasis is keeping the body stable, and vital signs show whether a person is maintaining homeostasis.