Homeostasis

Negative Feedback

-depresses or stops the conditions to return toward set point -Most conditions in the body

Positive Feedback

-enhances or continues the response away from set point -Examples: childbirth, blood clotting

Regardless of external conditions or activities, the body's internal temperature should be what?

37 degrees C 98.6 degrees F

Negative Feedback

A mechanism of homeostasis that acts in opposition to the stimulus. (Example: homeostasis of body temperature is an example of negative feedback. A stimulus takes the body away from the normal temperature and negative feedback mechanisms act to bring the temperature back to normal).

Positive Feedback

A physiological mechanism that acts to ENHANCE the original stimulus. Examples of positive feedback are less common for obvious reasons... blood clotting and labor during pregnancy are a couple of examples of positive feedback.

Receptors

A structure (sensory nerve ending) of the nervous system that detects stimuli. A structure which, on receiving environmental stimuli, produces an informative nerve impulse that is sent to the control center.

Examples of positive feedback

Blood clotting, oxytocin release in childbirth, milk release

What conditions must your body keep stable?

Body temperature, amount of water in body cells, amount of sugar in blood, amount of salt in body cells, chemical makeup of cells

Homeostasis

Body's ability to maintain internal stability, even when the external environment changes

Why do you breathe faster and deeper when you run?

Breathing changes to get more air into the lungs and more oxygen to the cells, which need it to release energy from nutrient molecules.

Function of the nervous system in maintaining homeostasis

Controls the secretion of endocrine glands

Control Center

Determines the levels to be maintained, analyzes information, and determines the appropriate response

What can long periods of stress do to homeostasis?

Disrupt homeostasis.

What is one main part of our body that helps keep balance?

Ear

Component of homeostasis that receivs informtin from the control center and returns the set point back to the appropriate level

Effector

Body systems involved in maintaining homeostasis

Endocrine and nervous

Purpose of antagonistic effectors

Finer degree of control for homeostasis

Typical control center in homeostasis

Hypothalamus

Skin (dermis layer) & the brain

Identify 2 places that temperature receptors are located in the body:

SWEAT GLANDS BLOOD VESSELS (smooth muscle of blood vessel that allows contraction or dilation of blood vessel) MUSCLES that contract (shivering)

Identify 3 specific EFFECTORS utilized in the homeostasis of body temperature.

example of negative feedback

In a negative feedback mechanism, the output shuts off the original stimulus. An example is the regulation of blood glucose levels. If there is a rise in blood glucose levels, those levels are detected by insulin secreting cells of the pancreas. Those insulin secreting cells are stimulated to release insulin into the blood. The liver then takes up the glucose and stores it as glycogen. Finally, the blood glucose levels decline to a set point,the stimulus for insulin release diminishes, and the body returns to homeostasis.

positive feedback example

In a positive feedback mechanism, the output exaggerates or enhance the original stimulus. An example is labor. During childbirth, a chemical called oxytocin is released causing more frequent and intensified contractions. As more contractions occur, the release of oxytocin increases. The mechanism is shut off when the baby exits the uterus.

Why is breathing deeper an example of homeostasis?

In homeostasis, the organ systems work together to keep conditions inside the body balanced. If your body needs more energy because it is expending lots of energy, the respiratory system will speed up the rate and amount of oxygen intake.

Effectors

Muscles or glands that receive a message from the control center and produce a desired EFFECT. Ex: produce sweat that allows water to evaporate from the surface of the skin and cool the body.

Functionof the control center in homeostasis

Receives information of system change (ie, set point) from sensors and sends instructions via effectors to make corrections

Component of homeostasis that detects changes in the body and sends the informtion to the control center

Receptor/Sensors

Control Center

Region of the brain (hypothalamus) that receives, interprets, and acts on the message sent from the receptors. The control center will then send an electrochemical message along the efferent pathway of nerves to the effectors (muscles and glands).

Function of the endocrine system in maintaining homeostasis

Secrete hormones to effect the function of the nervous system

Examples of negative feedback

Temperature, blood glucose, blood sodium, blood pressure

Set point

The average of a normal range of measurements. Conditions are stabilized above and below this "point"

Negative feedback

The body responds to a parameter change in the opposite direction of the change in order to maintain homeostasis. I.E., if temperature rises, the control center will send a response that lowers the temperature

Positive feedback

The body responds to a parameter change in the same direction of the change in order to amplify the change and is a subpart of negative feedback to maintain homeostasis. I.E., if the blood clots, the control center sends a response to continue the clotting

How does your body help maintain homeostasis when you are cold?

The body shivers when it is cold, burns more calories and moves blood to the core of the body.

How does you body help maintain homeostasis when you are hot?

The body sweats and pumps blood to the extremities.

Homeostasis

The body's ability to maintain relatively stable internal conditions even though the outside world is continuously changing.

Homeostasis

The condition in which the body's internal environment is kept stable.

Homeostasis

The mechanisms involved in the maintenance of a stable, internal environment. The body's ability to physiologically regulate its inner environment to ensure its stability in response to fluctuations in the outside environment.

Efferent Pathway

The nerve pathway sending an electrochemical message from the control center (hypothalamus of brain) to the effectors (muscles and glands).

Afferent pathway

The nerve pathway sending an electrochemical message from the receptors to the control center (hypothalamus of brain).

Why must conditions in you body keep stable?

The processes that keep an organism alive involve many kinds of chemical reactions that can take place only in specifically balanced environments.

Antagonistic effectors

The set point of a parameter is continually controlled by multiple effectors with opposing functions

Get enough Sleep, Eat a healthful diet, get plenty of exercise

What are three good ways to manage stress?

Sweating and thirst

What is the body's response to the stimulus of getting overheated?

What are some other ways in which the body maintains homeostasis other than cold and hot?

When the body needs water, you get thirsty. When the body needs food for energy, you get hungry.

What happens to your breathing when you run?

You breathe faster and deeper.

Effector

causes a response to change conditions

Stimulus

causes change

Nutrients

chemical substances used for energy and cell building

Receptors

monitors changes then sends information to the control center

Maintaining body temperature

necessary for chemical reactions to occur at life-sustaining rates

Oxygen

needed for metabolic reactions

What are the 5 survival Needs

nutrients oxygen water maintaining body temperature atmospheric pressure

Water

provides the necessary environment for chemical reactions

Atmospheric pressure

required for proper breathing and gas exchange in the lungs

Response

result of the stimulus

Set Point

the level that is to be maintained