Biological Bases of Behavior Nervous system and the endocrine system module 4

Module Overview Neurons: The Building Blocks of the Nervous System How Neurons Communicate The Structure of the Nervous System The Endocrine System

Neurons: The Building Blocks of the Nervous System Module 04: The Nervous System and the Endocrine System

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

Neuron A nerve cell; the basic building block of the nervous system. Neurons perform three basic tasks Receive information Carry the information Pass the information on to the next neuron

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

How Neurons Communicate: The Neural Impulse Module 04: The Nervous System and the Endocrine System

1. Action Potential A neural impulse: a brief electrical charge that travels down the axon of a neuron. Considered an “on” condition of the neuron – the neuron is ready to fire

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

The neuron is set and ready to fire 3. 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, then it always fires at the same intensity; all action potentials have the same strength. A neuron always fires at100% each time it fires.

How Neurons Communicate: Communication Between Neurons Module 04: The Nervous System and the Endocrine System

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

Neurotransmitters A chemical messenger that travels across the synapse from one neuron to the next and influences whether a neuron will generate an action potential.

Neurotransmitters

Neurotransmitters

Excitatory Effect/Inhibitory Effect Neurotransmitters (the chemical messenger between neurons) signal the next neuron to either fire (Excitatory) or not fire (Inhibitory)

How Neurons Communicate: The Neural Chain Module 04: The Nervous System and the Endocrine System

Four Types of Nerve Cells in the Neural Chain Receptor Cells Sensory Cells Interneurons Motor Nerves

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

A Neural Chain

Module 04: The Nervous System and the Endocrine System

Endocrine System

The Structure of the Nervous System Module 04: 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.

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.

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

Autonomic Nervous System The division of the peripheral nervous system that controls the glands and muscles of the internal organs; its subdivisions are the sympathetic (arousing) division and the parasympathetic (calming) division. Monitors the autonomic functions Controls breathing, blood pressure, and digestive processes

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

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

The Sympathetic and Parasympathetic Divisions of the Autonomic Nervous System

Studying the Brain: Scanning Techniques Module 05: The Brain

Computerized Axial Tomography (CT or CAT) Many X-ray photographs - combined into a representation of a slice of the brain or body

Magnetic Resonance Imaging (MRI) A technique that uses magnetic fields and radio waves to produce computer-generated images of the brain

Electroencephalogram (EEG) Amplified recording of the waves of electrical activity that across the brain’s surface measured by electrodes placed on the scalp -helpful in evaluating brain function.

Positron Emission Tomography Scan (PET scan) A visual display of brain activity. Injection of a radioactive glucose Reveals the brain’s functioning

Lower-Level Brain Structures: The Brainstem Module 05: The Brain

The oldest part and central core of the brain; Brainstem The oldest part and central core of the brain; begins with the spinal cord and swells as it enters the skull responsible for automatic survival functions.

Brainstem

Medulla Located at the base of the brainstem controls life-supporting functions like heartbeat and breathing. Damage to this area can lead to death.

Medulla

Reticular Formation A nerve network in the brainstem that plays an important role in controlling wakefulness and arousal. Extending up and down the spinal cord into the brain Controls an organism’s level of alertness Damage to this area can cause a coma.

Brainstem

Thalamus is Greek for “inner chamber.” The brain’s sensory switchboard, located on top of the brainstem; directs traffic to the sensory receiving areas in the cortex. Thalamus is Greek for “inner chamber.”

Thalamus

Thalamus

Cerebellum The “little brain”, attached to the rear of the brainstem; it helps coordinate voluntary movements and balance. If damaged, the person could perform basic movements but would lose fine coordination skills.

Cerebellum

Cerebellum

Lower-Level Brain Structures: The Limbic System Module 05: The Brain

Limbic System Ring of structures at the border of the brainstem and cerebral cortex; Helps regulate functions such as memory, fear, aggression, hunger, and thirst Includes the hypothalamus, hippocampus, and the amygdala.

Hypothalamus helps regulates the body’s maintenance activities, eating, drinking, body temperature, and is linked to emotion. Plays a role in emotions, pleasure, and sexual function

Hypothalamus

Hippocampus wraps around the back of the thalamus; it helps processing new memories for permanent storage. Looks something like a seahorse Hippo is Greek for “horse.”

Amygdala An almond shaped cluster in the limbic system that controls emotional responses such as fear and anger.

Amygdala

Cerebral Cortex The wrinkly upper portion of the brain forms body’s ultimate control and processing center Divided into four lobes Covers the brain’s lower level structures Contains an estimated 30 billion nerve cells

Corpus Callosum Longitudinal Fissure Band of neural fibers connecting the two brain hemispheres Allows communication between hemispheres The crevice that divides the cerebral cortex into left and right hemispheres.

Frontal Lobes Portion of the cerebral cortex just behind the forehead: involved in planning and judgment Also includes the motor cortex: A strip of brain tissue at the rear of the frontal lobes that controls voluntary movement

Frontal Lobe: Motor Cortex

Parietal Lobes Portion of the cerebral cortex on the top back portion of the head Includes the somatosensory cortex At the front of the parietal lobes: registers and processes body sensations. Regions available for general processing, including mathematical reasoning

Parietal Lobe: Somatosensory Cortex

Somatosensory Cortex

Temporal Lobes Portion of the cerebral cortex lying roughly above the ears Includes the auditory (hearing) areas of the brain. Where sound information is processed

Occipital Lobe Portion of the cerebral cortex lying at the back of the head it includes the primary visual processing areas of the brain.

Differences Between the Brain’s Two Hemispheres Module 05: The Brain

Hemispheric Differences “Left-brained” and “right-brained” debunked Brain is divided into two hemispheres but works as a single entity. Both sides continually communicate via the corpus callosum, except in those with split brains.

Differences Between the Two Hemispheres: Language and Spatial Abilities Module 05: The Brain

The Brain’s Left Hemisphere For most people, language functions are in the left hemisphere. For a small percentage of people, language functions are in the right hemisphere.

Broca’s Area A brain area of the left frontal lobe that directs the muscle movements involve in speech. If damaged the person can form the ideas but cannot express them as speech

Wernicke’s Area A brain area of the left temporal lobe involved in language comprehension and expression. Our ability to understand what is said to us

The Brain’s Right Hemisphere Houses the brain’s spatial abilities Our spatial ability allows us to perceive or organize things in a given space, judge distance, etc. Helps in making connections between words

Split Brain Research