WARM UP #1 12/14 You are walking alone and someone jumps out at you. 1.List 3 behavioral responses 2.List 3 physiological responses

CH 5 NOTES #1 12/14 Nervous System

Nervous system: Our body needs to communicate with its parts to know if there are any changes and to get it back to normal (homeostasis) PURPOSE: Sends messages around the body through nerves

PARTS: Brain, spinal cord, nerves Nerve cells: neurons

Nervous system and homeostasis 1. VOLUNTARY - you control BEHAVIORAL - Allows you to choose to do something Part of the brain used – CEREBRUM EX: running away, talking, jumping, walking, *any movement

HOW IT WORKS - VOLUNTARY Sensor Nerves Spinal cord Brain – cerebrum Spinal cord Nerves Muscles

DID YOU KNOW? The right side of your brain controls the left side of your body and vice versa

DID YOU KNOW? Different parts of the brain control different parts of your body

2. INVOLUNTARY - you don’t control PHYSIOLOGICAL - Causes your body do something on its own Part of the brain – BRAIN STEM EVERY SECOND – heartbeat, breathing, blinking, swallowing (medulla) WHEN NEEDED: blood pressure changes, temperature, sugar level, pain, goosebumps, digestion, pupil changes, sweat, etc.

QUESTION – BONUS POINTS 1.What does involuntary mean? 2.What part of your brain controls the voluntary? 3.Is physiological voluntary or involuntary?

HOW IT WORKS - INVOLUNTARY Sensors Nerves Spinal cord Brain – brain stem Spinal cord Nerves Glands or organs

2 divisions of the nervous system to help maintain homeostasis a. SYMPATHETIC – works in times of stress on your body “ fight or flight” - makes adrenaline release Prepares body to survive main priority = brain, heart, lungs, muscles

b.PARASYMPATHETIC – works in times of relaxing; brings your body back to normal AKA: “rest and digest” Main priority: digestive; being back to normal

BONUS POINTS S or P? 1.Heart beats faster 2.Digestion happens 3.Muscles tense up 4.Breath slower

How fast does all this happen? Around 280 miles per hour! Feels like it is instant

How does your body know that it needs to do something? SENSORS – cells that detect changes in our body. PURPOSE: so your body can respond and go back to homeostasis

REFLEX A fast reaction to protect the body that skips the brain. EX: blink, cough, move from hot, flinch, duck sneeze, gag

HOW IT WORKS - Reflex Sensor Nerves Spinal cord Nerves Muscle movement

NEGATIVE FEEDBACK Body senses change and it causes it to change back in the opposite direction EX: heart beats faster - heart beats slower blood pressure decreases - blood pressure increases

EX: BLOOD PRESSURE Increase in blood pressure Detected by the brain Message to heart message to arteries decrease dilate Blood pressure drop back to normal

ENDOCRINE SYSTEM Sends messages around the body through chemicals Glands – release hormones Hormones – chemicals released in blood that cause a reaction in the body

Endocrine system and homeostasis 1.Chemicals will cause your body to respond and maintain homeostasis EX: sugar balance water calcium balance ph

EXAMPLE

EXAMPLE: Blood sugar goes up after a meal Pancreas detects the rise and secrete insulin Insulin causes the liver and body cells to store the extra sugar Sugar back to normal

EXAMPLE: Body detect not enough water Message to brain Pituitary gland releases hormone Makes kidney hold onto water; thirsty Water balanced