Here's how it works:
* Sympathetic nervous system: This branch is responsible for the "fight-or-flight" response. When activated, it releases neurotransmitters like norepinephrine, causing:
* Increased heart rate: This pumps more blood per minute.
* Vasoconstriction (narrowing of blood vessels): This increases blood pressure by making it harder for blood to flow.
* Increased blood flow to muscles: This prepares the body for physical activity.
* Parasympathetic nervous system: This branch is responsible for the "rest-and-digest" response. When activated, it releases neurotransmitters like acetylcholine, causing:
* Decreased heart rate: This slows down the heart beat.
* Vasodilation (widening of blood vessels): This lowers blood pressure by making it easier for blood to flow.
* Increased blood flow to digestive organs: This promotes digestion.
The sympathetic and parasympathetic systems work together to maintain a balance in blood pressure, heart rate, and blood flow, ensuring the body's needs are met in various situations.
