Homeostasis

What are the different ways the body does homeostasis from the video of marathon runner?

Adrenaline is released which increases the heart rate. More fuel is available Muscles needed more oxygen. She starts to breathe faster to supply that oxygen. The heart rate also increases because of the needed oxygen Blood is going to the muscles and heart more because it is needed more in those areas The sweat glands releasing moisture. Evaporation occurs and it carries heat away from the body. When the level of glucose is too low fat is turned into glucose to be used as energy. Sensors in the brain detect the blood is becoming too concentrated. Hormones are released, and triggers a response in the kidneys. Urine levels go down, stabilizing the blood.

What are two mechanisms the body uses to heat itself?

Blood vessels in skin constrict, reducing heat loss and muscles begin to shiver, generating heat.

What are two mechanisms the body uses to cool itself?

Blood vessels in skin dilate to radiate heat and sweat glands increase sweat production.

What is an example of a positive feedback loop in human physiology?

Childbirth. Pressure on cervix causes oxytocin release and contractions which causes more pressure on the cervix which causes more oxytocin release and contractions.

Is thermoregulation when someone is hot a positive or negative feedback loop?

Negative because it is decreasing the temperature (decreasing the stimulus)

Is thermoregulation when someone is cold a positive or negative feedback loop?

Negative because it is increasing the temperature (decreasing the stimulus)

What type of feedback is part of homeostasis?

Negative feedback

Which of the feedback mechanisms would be most useful for stopping a condition that is detrimental or limiting a condition to specified levels?

Negative feedback

Which of the feedback mechanisms would be most useful for amplifying a condition that is advantageous for the organism?

Positive feedback

Negative feedback

Stimulus causes a response which DECREASES the stimulus. You get hungry - eat food - get less hungry

Positive feedback

Stimulus causes a response which INCREASES the stimulus (up-regulates). This is more common behaviorally than in the body.

What portion of the brain contains sensors that monitor body Temperature?

The hypothalamus

Define Thermoregulation

The process by which animals maintain an internal temperature within a tolerable range. A process that takes place when your body temperature is to high or low and your body needs to regulate its temperature.

When a human increases physical activity, the amount of fuel burned in its cells also increases, which in turn increases the concentration of dissolved CO2 in the blood. The CO2 reacts with water in the blood to make a weak acid, which lowers the pH of the blood. Sensory cells in the medulla of the brain register this drop in pH and send signals to the diaphragm and heart to increase respiration. This will clear the CO2 from the bloodstream. What is stimulus, what is response, is this positive or negative feedback?

The stimulus is an increase in physical activity and increase in CO2 and acidity in the blood and the response is clearing CO2 from the bloodstream. This is an example of negative feedback.

When a person has not taken in sufficient water they become dehydrated. This may cause a loss of blood pressure, which will trigger the release of antidiuretic hormone (ADH) from the hypothalamus and pituitary glands. This hormone signals the kidney to allow reabsorption of water by the blood vessels to bring the blood pressure back to normal conditions. What is stimulus, what is response, is this positive or negative feedback?

The stimulus is not drinking enough water and the response is the release of antidiuretic hormone and resorbing water into the blood vessels. This is an example of negative feedback.

When human tissue, such as skin or a blood vessel, is torn or cut, the cells near the damage send out a signal that activates platelets in the vicinity. As the platelets begin to form a plug, they release more chemical signals to attract more platelets and other clotting factors until the bleeding is stopped. What is stimulus, what is response, is this positive or negative feedback?

The stimulus is skin or blood vessel being cut and the response is they release more chemical signals to attract more platelets and other clotting factors until the bleeding is stopped. This is an example of negative feedback.

Identify a "stimulus" and "response" in the thermoregulation feedback loop.

The temperature being to high is the stimulus and the response is the blood vessels in skin dilate to radiate heat and sweat glands increase sweat production.

Consider the feedback loop that heats the body when it is too cold. Identify the "stimulus" and "response" in the feedback loop

The temperature being too low is the stimulus and the blood vessels in skin constricting, reducing heat loss and muscles beginning to shiver, generating heat is the response

What are two more ways our bodies maintain homeostasis?

Waste removal and temperature control