The Brain and The Nervous System

Brain Facts The brain weighs 3 pounds. The brain consumes 20-30% of the body’s energy. There are about 100 billion neurons in the brain. The most sophisticated computer is currently only as complicated as a rat’s brain The brain weighs 3 pounds. The brain consumes 20-30% of the body’s energy. There are about 100 billion neurons in the brain. The most sophisticated computer is currently only as complicated as a rat’s brain

More Brain Facts By the age of 6, the brain has reached 90 to 95% of its adult size. A teenage brain keeps growing and changing throughout adolescence and well into the twenties. By the age of 6, the brain has reached 90 to 95% of its adult size. A teenage brain keeps growing and changing throughout adolescence and well into the twenties.

What is a Neuron? A nerve cell which is the basic unit of the nervous system It consists of:  Dendrites (nerve fiber) which carries impulses toward the cell body  Axon (single nerve fiber) which carries impulses away from the cell body A nerve cell which is the basic unit of the nervous system It consists of:  Dendrites (nerve fiber) which carries impulses toward the cell body  Axon (single nerve fiber) which carries impulses away from the cell body

Synapses The space between the axons and dendrites Impulses coming from one axon “jump” the synapse to get to the dendrite of another neuron Neurotransmitters allow the impulses to pass from one neuron to another The space between the axons and dendrites Impulses coming from one axon “jump” the synapse to get to the dendrite of another neuron Neurotransmitters allow the impulses to pass from one neuron to another

Neuron Networks

Myelin Fatty substance (called myelin sheath) that coats part of each neuron 1. Improves the neuron communication 2. Makes the brain more efficient 3. Facilitates multitasking Fatty substance (called myelin sheath) that coats part of each neuron 1. Improves the neuron communication 2. Makes the brain more efficient 3. Facilitates multitasking

Nervous System 2 main systems 1. The Central Nervous System (consist of the brain and the spinal cord) 2. The Peripheral Nervous System consists of: a. nerves b. separate division called Autonomic Nervous System 2 main systems 1. The Central Nervous System (consist of the brain and the spinal cord) 2. The Peripheral Nervous System consists of: a. nerves b. separate division called Autonomic Nervous System

Central & Peripheral Nervous Systems

Peripheral Nerves Includes: 12 pairs of cranial nerves 31 pairs of spinal nerves Includes: 12 pairs of cranial nerves 31 pairs of spinal nerves

Autonomic Nervous System Controls involuntary body functions Involves 2 divisions: 1. Sympathetic Prepares the body to act during an emergency/ “Fight or Flight” reaction 2. Parasympathetic Counteracts the body’s reaction to an emergency Both work together to create Homeostasis (balanced state) Controls involuntary body functions Involves 2 divisions: 1. Sympathetic Prepares the body to act during an emergency/ “Fight or Flight” reaction 2. Parasympathetic Counteracts the body’s reaction to an emergency Both work together to create Homeostasis (balanced state)

Sympathetic Nervous System Pupils: dilate (get larger) Saliva: decrease production Heart Rate: increase pulse Bronchi: dilation of airways Digestion: decrease activity Bladder: decrease urine output Pupils: dilate (get larger) Saliva: decrease production Heart Rate: increase pulse Bronchi: dilation of airways Digestion: decrease activity Bladder: decrease urine output

Parasympathetic Nervous System Pupils: return to normal Saliva: increase production Heart Rate: decrease pulse Bronchi: constriction of airway Digestion: increase activity Bladder: increase urine output Pupils: return to normal Saliva: increase production Heart Rate: decrease pulse Bronchi: constriction of airway Digestion: increase activity Bladder: increase urine output

Parasympathetic vs. Sympathetic Nervous Systems

What protects the Brain? MEMBRANE TISSUE CEREBROSPINAL FLUID SKULL BONES MEMBRANE TISSUE CEREBROSPINAL FLUID SKULL BONES

The Meninges Three membranes that cover and protect the brain and spinal cord Dura Mater – thick, tough, outer layer Arachnoid Membrane – delicate, weblike middle layer Pia Mater – innermost layer containing blood vessels Three membranes that cover and protect the brain and spinal cord Dura Mater – thick, tough, outer layer Arachnoid Membrane – delicate, weblike middle layer Pia Mater – innermost layer containing blood vessels

The Ventricles Four hollow spaces under the arachnoid membrane (subarachnoid space) Contains cerebrospinal fluid This fluid is produced by the choroid plexuses and continuously circulates through the ventricles Serves as a shock absorber to protect the brain Four hollow spaces under the arachnoid membrane (subarachnoid space) Contains cerebrospinal fluid This fluid is produced by the choroid plexuses and continuously circulates through the ventricles Serves as a shock absorber to protect the brain

Main Sections of the Brain 1. Cerebrum Largest part of the brain Outer part is arranged in folds called convolutions, and separated into lobes. Lobes: Frontal Parietal Temporal Occipital 1. Cerebrum Largest part of the brain Outer part is arranged in folds called convolutions, and separated into lobes. Lobes: Frontal Parietal Temporal Occipital

The cerebrum is responsible for reasoning, thought, memory, speech, sight, smell, hearing, and involuntary body movement.

Sections of the Brain 2. Cerebellum Located below the back part of the cerebrum Responsible for: Muscle Coordination Balance Posture Muscle Tone 2. Cerebellum Located below the back part of the cerebrum Responsible for: Muscle Coordination Balance Posture Muscle Tone

Brain Diagram Cerebellum

Sections of the Brain 3. Diencephalon Located between the cerebrum and midbrain Contains the thalamus and hypothalamus The thalamus acts as the relay center and direct sensory impulses to the cerebrum 3. Diencephalon Located between the cerebrum and midbrain Contains the thalamus and hypothalamus The thalamus acts as the relay center and direct sensory impulses to the cerebrum

The Hypothalamus regulates/controls: The Autonomic Nervous System Temperature Appetite Water Balance Sleep Constriction/Dilation of Blood Vessels Emotions: anger, fear, pleasure, pain, and affection The Autonomic Nervous System Temperature Appetite Water Balance Sleep Constriction/Dilation of Blood Vessels Emotions: anger, fear, pleasure, pain, and affection

Brain Diagram Thalamus Hypothalamus

Sections of the Brain 4. Midbrain Located below the cerebrum at the top of the brain stem Responsible for conducting impulses between the brain and certain eye and auditory (hearing) reflexes 4. Midbrain Located below the cerebrum at the top of the brain stem Responsible for conducting impulses between the brain and certain eye and auditory (hearing) reflexes

Sections of the Brain 5. Pons Located below the midbrain and in the brain stem Responsible for reflex actions such as: Chewing Tasting Saliva Production Spontaneous Respirations 5. Pons Located below the midbrain and in the brain stem Responsible for reflex actions such as: Chewing Tasting Saliva Production Spontaneous Respirations

Brain Diagram Midbrain Pons

Sections of the Brain 6. Medulla Oblongata Located on the lowest part of the brain stem Responsible for: Swallowing Coughing Regulation of heartbeat, respirations, & Blood Pressure 6. Medulla Oblongata Located on the lowest part of the brain stem Responsible for: Swallowing Coughing Regulation of heartbeat, respirations, & Blood Pressure

Brain Diagram

The Spinal Cord Continues down from the medulla oblongata Ends at the first or second lumbar vertebrae Responsible for many reflex actions Continues down from the medulla oblongata Ends at the first or second lumbar vertebrae Responsible for many reflex actions

Carries sensory (afferent) messages to the brain Carries motor (efferent) messages from the brain to nerves The Spinal Cord

How are you using your Brain? THE END