Biology & Behavior

Fact or Falsehood! 1. All behavior is governed by whether or not a neuron, the basic cell of the nervous system, is activated (fires). 2. Strong emotions, like anger, result from more intense firing of neurons. 3. Neurons never actually touch one another. 4. Drugs work either to mimic or mask one of the body’s naturally occurring chemicals, called neurotransmitters. 5. The brain directly processes all sensory information that comes into the body. 6. Your voluntary movements and your involuntary movements (breathing, digestion, heartbeat, etc.) are controlled by two different nervous systems. 7. You have a specialized nervous system that is responsible for calming you down after a stressful situation. 8. The adrenal glands are responsible for telling the rest of the body what hormones to secrete.

Answers 1. T 2. F 3. T 4. T 5. F 6. T 7. T 8. F

Neuron The neuron or nerve cell is adapted for receiving and sending signals. Three major regions of the neuron enable the cell to communicate with other cells.

Parts of the Neuron

Dendrites 1. The dendrites are branching tubular processes capable of receiving information.

Parts of the Neuron - Dendrites Dendrite – The branching extensions of a neuron that receive information and conduct impulses toward the cell body

The Cell Body 2. The cell body (a.k.a. cyton or soma) contains cytoplasm and the nucleus which directs synthesis of such substances as neurotransmitters.

Parts of the Neuron - Soma Soma – The cell body of a neuron, which contains the nucleus and other parts that keep the cell healthy

Axon 3. The axon emerges from the cell body as a single conducting fiber (longer than a dendrite) which branches and ends in tips called axon terminals (a.k.a. terminal boutons, terminal buttons, synaptic knobs or end feet).

Parts of the Neuron - Axon Axon – The extension of a neuron through which neural impulses are sent

Axon The axon may be covered by an insulating myelin sheath. Spaces between segments of myelin are called nodes of Ranvier. (This was on our slide from the play-doh yesterday.)

Parts of the Neuron – Myelin Sheath

Parts of the Neuron - Terminals Axon terminals – The endpoint of a neuron where neurotransmitters are stored

Thinking time! Why aren’t we “hard-wired?” In other words, why don’t our nerves actually connect to each other?

Nervous System The electrochemical communication system of the body Sends messages from the brain to the body for movement Brings information to the brain from the senses

How Neurons Communicate: The Neural Impulse Module 6: The Nervous System and the Endocrine System How Neurons Communicate: The Neural Impulse

Activity Time! Everyone line up in one long line around the classroom. Put your hands on the shoulders of the person in front of you and follow my instructions. Why were the slow times slower and why were the quicker times fast? First practice with hands on shoulders a couple of times. Then switch to ankles. Then do both hands with squeezing same shoulder. Finally, both hands, squeezing opposite shoulder from what the person behind you did.

Action Potential A neural impulse; a brief electrical charge that travels down the axon of a neuron Considered an “on” condition of the neuron

Action Potential

Refractory Period The “recharging phase” during which a a neuron, after firing, cannot generate another action potential Once the refractory period is complete the neuron can fire again

Refractory Period

Resting Potential The state of a neuron when it is at rest and capable of generating an action potential The neuron is set and ready to fire

Resting Potential

All-or-None Principle The principle stating that if a neuron fires it always fires at the same intensity All action potentials are of the same strength. A neuron does NOT fire at 30%, 45% or 90% but at 100% each time it fires.

How Neurons Communicate: Communication Between Neurons Module 6: The Nervous System and the Endocrine System

Synapse The tiny, fluid filled gap between the axon terminal of one neuron and the dendrite of another neuron The action potential cannot jump the gap

Neurotransmitters A chemical messenger that travels across the synapse from one neuron to the next Can influence whether the second neuron will generate an action potential or not

Neurotransmitters

Work time! Complete the diagram.

Neurotransmitters

Excitatory Effect A neurotransmitter effect that makes it more likely that the receiving neuron will generate an action potential or “fire” The second neuron is more likely to fire.

Inhibitory Effect A neurotransmitter effect that makes it less likely that the receiving neuron will generate an action potential or “fire” The second neuron is less likely to fire.

How Neurons Communicate: The Neural Chain Module 6: The Nervous System and the Endocrine System

Receptor Cells Specialized cells in the sensory systems of the body that can turn other kinds of energy into action potentials (neural impulses) that the brain can process Receptor cells in the eye turn light into a neural impulse the brain understands.

Sensory Nerves Nerves that carry information from the sensory receptors to the spinal cord and brain. Connect the sense organs to the brain and spinal cord

Interneurons Nerve cells in the brain and spinal cord responsible for processing information Related to sensory input and motor output

Motor Nerves Nerves that carry information from the brain and spinal cord to the muscles and glands. Carries messages from the brain and spinal cord to other parts of your body

The Structure of the Nervous System Module 6: The Nervous System and the Endocrine System

The Nervous System

Central Nervous System (CNS) The brain and spinal cord The brain is the location of most information processing. The spinal cord is the main pathway to and from the brain. Also has spinal reflexes

Divisions of the Nervous System

Peripheral Nervous System (PNS) The sensory and motor nerves that connect the brain and the spinal cord to the rest of the body Peripheral means “outer region” The system is subdivided into the somatic and autonomic nervous systems.

Divisions of the Nervous System

Somatic Nervous System The division of the peripheral nervous system that controls the body’s skeletal muscles Contains the motor nerves needed for the voluntary muscles

Divisions of the Nervous System

Autonomic Nervous System The division of the peripheral nervous system that controls the glands and muscles of the internal organs Monitors the autonomic functions Controls breathing, blood pressure, and digestive processes Sub-divided into the sympathetic and parasympathetic nervous systems

Divisions of the Nervous System

Sympathetic Nervous System The part of the autonomic nervous system that arouses the body to deal with perceived threats Fight or flight response

Divisions of the Nervous System

Sympathetic nervous system Why does it do this, using our bear example?

Parasympathetic Nervous System The part of the autonomic nervous system that calms the body Brings the body back down to a relaxed state

Divisions of the Nervous System

Parasympathetic Why does it do this, still using our example?

Module 6: The Nervous System and the Endocrine System

Endocrine System One of the body’s two communication systems A set of glands that produce hormones-- chemical messengers that circulate in the blood

Hormone Chemical messengers produced by the endocrine glands and circulated in the blood Similar to neurotransmitters in that they are also messengers Slower communication system, but with longer lasting effects

Pituitary Gland The endocrine system’s gland that, in conjunction with the brain, controls the other endocrine glands Called the “master gland” Located at the base of the brain and connects to the hypothalamus

Endocrine System – Pituitary Gland

Thyroid Gland Endocrine gland that helps regulate the energy level in the body Located in the neck

Endocrine System – Thyroid Gland

Adrenal Gland Endocrine glands that help to arouse the body in times of stress Located just above the kidneys Release epinephrine (adrenaline) and norepinephrine (noradrenaline)

Endocrine System – Adrenal Gland

Pancreatic Gland Regulates the level of blood sugar in the blood

Endocrine System – Pancreatic Gland

Sex Glands Ovaries (females) and testes (males) are the glands that influence emotion and physical development. Testosterone – primary males hormone Estrogen – primary female hormone Males and females have both estrogen and testosterone in their systems.

Endocrine System – Sex Glands

The End! Thank you for your attention. Go Eagles.