The Nervous and Endocrine The Nervous and Endocrine Systems…Communication…Systems…Communication…

The Nervous SystemThe Nervous System

How do we know when to eat?How do we know when to eat? How do we know if we are touching a How do we know if we are touching a

hot stove?hot stove? How does our body control breathing, How does our body control breathing,

the heart beat, and all other functions the heart beat, and all other functions without our thinking about them?without our thinking about them?

The answer to all of these is the The answer to all of these is the nervous systemnervous system

The Nervous SystemThe Nervous System

Our nervous system is Our nervous system is how all of the parts of how all of the parts of our body communicate our body communicate with all of the other with all of the other parts…its why we parts…its why we aren’t a bunch of aren’t a bunch of separate parts doing separate parts doing their own thing….their own thing….

NeuronsNeurons

The cells in the nervous system are called The cells in the nervous system are called neuronsneurons

Neurons contain a cell body with a nucleusNeurons contain a cell body with a nucleus They also have dendrites (dozens) that They also have dendrites (dozens) that

receive signals either from other neurons or receive signals either from other neurons or from the environmentfrom the environment

They have an axon (one) as well that sends They have an axon (one) as well that sends the signal on to the next neuron (away from the signal on to the next neuron (away from the cell body)the cell body)

A typical neuronA typical neuron

Nerve Nerve impulsesimpulses A bundle of axons make up nervesA bundle of axons make up nerves Nerve impulses travel really quickly (250 miles Nerve impulses travel really quickly (250 miles

per hour…400 km per hour)per hour…400 km per hour) When they get to the end of an axon they must When they get to the end of an axon they must

cross the synapse…the gap between the cross the synapse…the gap between the neuronsneurons

They do this by causing chemicals They do this by causing chemicals (neurotransmitters) to be released that cross (neurotransmitters) to be released that cross and create a new impulse at the other sideand create a new impulse at the other side

Structures of the nervous Structures of the nervous systemsystem

Neurons are the smallest parts of the Neurons are the smallest parts of the nervous system but they come together to nervous system but they come together to form two partsform two parts The central nervous systemThe central nervous system

The brain and spinal cordThe brain and spinal cord The peripheral nervous systemThe peripheral nervous system

The smaller nerves that send impulses to and from The smaller nerves that send impulses to and from the organs (sensory neurons) and the muscles the organs (sensory neurons) and the muscles (motor neurons)(motor neurons)

Questions…Questions…

How is the nervous system How is the nervous system involvedinvolved in controlling your digestion?in controlling your digestion?

helping you play soccer?helping you play soccer?

helping you read a book?helping you read a book?

in controlling our heart rate?in controlling our heart rate?

The Endocrine SystemThe Endocrine System

The endocrine system is The endocrine system is another way that your body another way that your body communicatescommunicates with itself. with itself.

Instead of a nerve impulse, Instead of a nerve impulse, your body secretes your body secretes hormoneshormones that regulate the that regulate the activity of other cells.activity of other cells.

HormonesHormones

HormonesHormones are substances secreted by cells are substances secreted by cells that regulate the activity of other cellsthat regulate the activity of other cells

The functions of hormones include:The functions of hormones include: Regulating growth, development, behavior, and Regulating growth, development, behavior, and

reproductionreproduction Coordinating the production, use, and storage of Coordinating the production, use, and storage of

energyenergy Maintaining homeostasis (temperature, salt Maintaining homeostasis (temperature, salt

balance, metabolism, excretion)balance, metabolism, excretion) Responding to stimuli from outside the bodyResponding to stimuli from outside the body

Examples:Examples:

Have you ever had a “fight or flight” response?Have you ever had a “fight or flight” response? You see a snake?You see a snake? You are about to get caught cheating on a big test?You are about to get caught cheating on a big test? You know that killer zombies are after your brains?You know that killer zombies are after your brains?

When you haven’t eaten in a while, how does When you haven’t eaten in a while, how does your body control blood glucose levels?your body control blood glucose levels? Glucagon and insulin tell the body to either store Glucagon and insulin tell the body to either store

glucose and glycogen or to convert the glycogen glucose and glycogen or to convert the glycogen back to glucoseback to glucose

Endocrine GlandsEndocrine Glands

Hormones are produced in the Hormones are produced in the endocrine endocrine glandsglands

These glands secrete hormones directly into These glands secrete hormones directly into the blood or the fluid around the cellsthe blood or the fluid around the cells

The endocrine glands can act independently or The endocrine glands can act independently or together to help maintain homeostasistogether to help maintain homeostasis

The The pituitary gland pituitary gland is the “master gland”- it is the “master gland”- it secretes hormones that regulate all of your secretes hormones that regulate all of your other glands.other glands.

Glands Hormones Function

Adrenal glands aldosterone

cortisol

Maintains salt-and-water balance Regulates carbohydrates and protein metabolism

Adrenal glands epinephrine

norepinephrine

“fight or flight” response

Ovaries estrogen

progesterone

Regulates female characteristics and Maintains growth of uterine lining

Pancreas Glucagon

Insulin

Stimulates the release of glucose

Stimulates the absorption of glucose

Testes Androgens (testosterone)

Regulates male characteristics

RelationshipsRelationships

The nervous system The nervous system and endocrine and endocrine system both help system both help regulateregulate ALL of our ALL of our body systems body systems because they are because they are how they how they communicatecommunicate with with each other!each other!