Biology

• homeostasis is the maintenance of a constant internal environment despite changes in the external environment
• negative feedback is when the body responds to a change in the environment to restore the original condition if the system deviates too far from the set point
• positive feedback is when, instead of getting a counteracting response to some variable, you instead intensify the variable
• the hypothalamus monitors the conditions inside the body and sends signals to the pituitary gland
• vasoconstriction is when blood vessels contract to reduce blood flow to the skin. Less blood near the surface means less heat will be lost.
• vasodilation is when the blood vessels dilate to increase blood flow to the muscles. When blood is near the skin's surface, the heat is able to leave the body
• sweating helps reduce body temperature by evaporating sweat from the skin and cooling the body. The heat from blood moves into the sweat and it absorbs enough heat it evaporates.
• Sweating is most effective in low humidity environments
• piloerection is when hairs on the skin stand up to trap a layer of insulating air close to the body which prevents further heat loss. The small muscles at the base of your hairs contract which caused the hairs to stand up.
• goosebumps are contracted muscles at the base of your hairs
• shivering is involuntary contractions of the body's muscles. Whenever chemical reactions (metabolism) happens in the body, heat is produced.
• Shivering is the result of chemical reaction and therefore it produces heat
• hormones are chemical substances that are produced by glands and travel in the bloodstream
• hormones are sent by the bloodstream that travel through the circulatory system to the target cell's receptors.
• adrenal glands produce the hormone adrenaline
• adrenaline is a hormone that increases the heart rate and blood pressure to prepare the body for fighting or fleeing danger
• positive feedback loop

  pressure of childs head on cervix -> pain/pressure receptor -> brain detects stimulus -> oxytocin released which causes more contractions -> baby is born