Intro to Body Systems and the Nervous System

Intro to Body Systems and the Nervous System 12 major systems

Multicellular humans The human body contains 50 to 75 trillion cells Cells are organized and given a specific task to make the whole organism work

How are humans organized? Cells (~300 types) Tissues (4 tissue types) Organs Organ System (12 organ systems) Organism

Cell Differentiation All of your cells have the exact same DNA with the exact same information yet there are 300 types of cells How do they become differentheart, lung, skin, etc……? *Certain genes get turned on while others get turned off in each of the different types of cell

Homeostasis- The process by which organisms keep constant/near constant internal conditions despite changes in the external environment The nervous and endocrine systems are in charge of maintaining homeostasis.

Nervous System Function Body system made up of cells that control and coordinate the other body systems to maintain homeostasis and respond to internal and external condidtions Simplified—It’s the body’s major communication system

Neurons The cells that make up the nervous system are called neurons These cells carry information in the form of electric and chemical signals called nerve impulses Information is electric through the neuron and chemical between Resting potential- no electric signal Action potential- carrying an electric signal

3 types of neurons 1) sensory neurons = senses nerve cells that gather information and send it to the brain 2) Internerons = interpret information nerve cells that make up your brain 3) motor neurons = movement nerve cells that carry messages from the brain to the body for movement

Activating the nervous system Stimuilus- anything that activates a sensory neuron Name the stimulus sensory neurons in eyessensory neurons in earssensory neurons in bodysensory neurons in nosesensory neurons in mouth-