UNIT B Chapter 12 Nervous System Section 12

UNIT B Chapter 12: Nervous System Section 12. 3 The Central Nervous System • Receives sensory information and initiates motor control • Composed of the spinal cord and the brain. • Brain: controls breathing, heart rate, body temperature, blood pressure, emotions, reasoning, memory, and creativity • Spinal cord: a means of communication between the brain and the peripheral nerves that leave the cord TO PREVIOUS SLIDE

UNIT B Chapter 12: Nervous System Figure 12. 7 Organization of the nervous system. The CNS is composed of the spinal cord and brain. The PNS is composed of the motor and sensory pathways. TO PREVIOUS SLIDE Section 12. 3

Brain and Spinal Cord both: • Contain gray matter (cell bodies and short, nonmyelinated fibers) and white matter (myelinated axons that run in tracts), • protected by bone, • wrapped in protective membranes called meninges, • surrounded and cushioned with cerebrospinal fluid that is produced in the ventricles of the brain. • Composed of gray and white matter

Nerve - a whitish bundle of nerve fibers (axons)

Cerebral Spinal Fluid (CSF) • Produced by ventricles (hollow cavities) and the spinal cord’s central canal 1. Cushions the brain to prevent injury 2. Removes waste products of the brain's metabolism 3. Maintains a constant pressure within the brain — compensating for changes in blood pressure in the brain Improper drainage hydrocephalus

UNIT B Chapter 12: Nervous System Section 12. 3 The Spinal Cord Structure • Individual vertebra protect the spinal cord • Spinal nerves project from the cord between the vertebrae in the vertebral column • Fluid-filled intervertebral disks cushion and separate the vertebrae TO PREVIOUS SLIDE Figure 12. 8 Spinal cord. a. The spinal cord passes through the vertebral canal formed by the vertebrae.

Herniated Disk

UNIT B Chapter 12: Nervous System • Central canal: contains cerebrospinal fluid • Grey matter: inner “H” o parts of sensory, motor, and interneurons • Dorsal root: sensory fibres entering grey matter • Ventral root: motor fibres exiting grey matter • Spinal nerves: part of PNS TO PREVIOUS SLIDE Section 12. 3

UNIT B Chapter 12: Nervous System White matter: • ascending tracts take information to the brain, dorsal • descending tracts take information from the brain and are ventral • Tracts cross each other after entering and exiting CNS • Left side of brain: controls right side of body • Right side of brain: controls left side of body TO PREVIOUS SLIDE Section 12. 3

UNIT B Chapter 12: Nervous System Section 12. 3 Functions of the Spinal Cord 1. Communication between Brain and PNS o Example: Voluntary movement o When we move our limbs, motor impulses in the brain pass down descending tracts to the spinal cord and out to our muscles through motor fibres 2. Center for Reflex Arcs- Involuntary and nearly instantaneous movement in response to a stimulus. TO PREVIOUS SLIDE

Take on line Quiz https: //highered. mheducation. com/sites/0072351136/student_vie w 0/chapter 12/chapter_quiz. html

CNS Crash course: CNS https: //www. youtube. com/watch? v=q 8 Ntm. Drb_qo

1 7 1 6 The human brain

UNIT B Chapter 12: Nervous System TO PREVIOUS SLIDE Section 12. 3 Figure 12. 9 The human brain. a. The cerebrum, seen here in longitudinal section, is the largest part of the brain in humans. The right cerebral hemisphere is shown here.

Brain has 4 ventricles

UNIT B Chapter 12: Nervous System The Brain has 4 main parts All have primary function and adjacent association areas that integrate signals TO PREVIOUS SLIDE Section 12. 3

Forebrain – highest, differentiates humans from animals (Telencephalon, Diencephalon) 1. Cerebral Cortex 2. Thalamus – on top of brain stem; sorts and relays incoming info to appropriate forebrain areas (cerebellum to motor cortex). Also works with Retic Formation on reg sleep and wakefulness 3. Hypothalamus – below thalamus. Monitors pleasurable activties (eating, drinking, sex). Influences endocrine system, esp pituitary in response to emotions, stress and rewards. 4. Basal Ganglia –cluster of neurons b/t thalamus and cortex, works with cortex and cerebellum for coordinating voluntary movements and habitual behaviours (cycling, typing) 5. Limbic System – Amygdala (processes emotions) and hippocampus (memory storage)

UNIT B Chapter 12: Nervous System Section 12. 3 The Cerebrum (Telencphalon) • largest part of the brain in humans • Communicates with and coordinates activities of other parts of the brain • Higher thought processes (learning, memory, language, speech. TO PREVIOUS SLIDE

UNIT B Chapter 12: Nervous System Structure and Function Cerebrum • Two cerebral hemispheres communicate via the corpus callosum, a bridge of nerve tracts. • The cerebral cortex is a thin outer layer of grey matter covering the cerebral hemispheres • Grooves called sulci divide the hemisphere into four lobes: frontal, parietal, occipital, temporal • Gyri – bumps TO PREVIOUS SLIDE Section 12. 3

1 7 2 4 The lobes of a cerebral hemisphere

UNIT B Chapter 12: Nervous System Section 12. 3 Frontal Lobe of Cerebral Cortex • Primary motor area: involved in voluntary movement • Premotor area: organizes motor functions and sends signals to cerebellum for integration • Prefrontal area: processing centre involved in reasoning and planning (appropriate behaviour) • Broca’s area: involved in speech musculature (lips, tongue, larynx) TO PREVIOUS SLIDE

UNIT B Chapter 12: Nervous System Section 12. 3 Parietal Lobe (dorsal to central sulcus) • Primary somatosensory area: involved in somatic sensing • Primary taste area: involved in taste • Somatosensory association area: processes and analyzes sensory information from skin and muscles TO PREVIOUS SLIDE

UNIT B Chapter 12: Nervous System Section 12. 3 Temporal Lobe • Primary auditory area: involved in hearing • Auditory association area: associates new audio information with previous audio information • Wernicke’s area: helps us understand written and spoken words TO PREVIOUS SLIDE

UNIT B Chapter 12: Nervous System Section 12. 3 Occipital Lobe • Primary visual area: involved in vision • Visual association area: associates new visual information with previous visual information (e. g. , facial recognition) TO PREVIOUS SLIDE

UNIT B Chapter 12: Nervous System TO PREVIOUS SLIDE Section 12. 3 12. 11 The primary motor and somatosensory areas. In these drawings, the size of the body part reflects the amount of cerebral cortex devoted to that body part. For example, the amount of primary motor cortex (a) and somatosensory cortex (b) devoted to the thumb, fingers, and hand is greater than that for the foot and toes.

Homunculus

UNIT B Chapter 12: Nervous System Section 12. 3 Central White Matter • consists mostly of long myelinated axons forming tracts; • cross over so the left side of the brain handles right side information. • Most of the cerebrum beneath the cerebral cortex is composed of white matter TO PREVIOUS SLIDE

Basal Ganglia • masses of grey matter located deep within the white matter of the cerebrum • Integrate motor commands to ensure proper muscle groups are activated or inhibited • Habitual behaviour such as typing or biking

Gray and White Matter

UNIT B Chapter 12: Nervous System The Diencephalon • Hypothalamus and thalamus, pineal gland, third ventricle TO PREVIOUS SLIDE Section 12. 3

UNIT B Chapter 12: Nervous System Hypothalamus • Integrating centre that helps maintain homeostasis • Regulates hunger, sleep, thirst, body temperature, and water balance, pleasure and pain, satisfaction, anger and aggressive behavior • Controls the pituitary gland: a link between the nervous and endocrine systems TO PREVIOUS SLIDE Section 12. 3

UNIT B Chapter 12: Nervous System Section 12. 3 Thalamus • Two masses of grey matter that receive all sensory input except smell • Integrates visual, auditory, taste, and somatosensory information from spinal cord and sends it to the appropriate area in the cerebrum • Involved in higher mental functions (memory, emotions) Pineal gland • Secretes the hormone melatonin, which is involved in maintaining a normal sleep-wake cycle TO PREVIOUS SLIDE

1 7 3 7 Limbic system

1 7 3 8 The Limbic System • Controls our Emotions • Blends primitive emotions and higher mental functions, such as learning and formation of memories. • amygdala, hippocampus, thalamus, hypothalamus, basal ganglia, and cingulate gyrus. • hippocampus and amygdala are essential for learning and memory.

Amygdala Responsible for the response and memory of emotions, especially fear

Hippocampus Role in the formation of new memories about past experiences. Responsible for processing of long term memory and emotional responses. Prefontal area consults hippocampus in order or use memories to modify behaviour.

Check your progress 1. The ____ lobe contains the visual cortex. A) frontal B) parietal C) temporal D) Occipital 2. The ____ connects the two cerebral hemispheres. A) limbic system B) corpus callosum C) cerebellum D) pituitary

3. Neurons in the ____ control motor reflexes. A) thalamus B) spinal cord C) parietal lobe D) Hippocampus 4. What methods can be used to determine the function of a particular brain region? 5. What are the main functions of the spinal cord?

UNIT B Chapter 12: Nervous System Section 12. 3 The Brain Stem Contains the midbrain and hind brain (pons, and medulla oblongata, cerebellum) TO PREVIOUS SLIDE

Mid brain (mesencephalon) • Relays info between hind brain and forebrain • Has reflex centres for visual, auditory, and tactile responses 2 systems: 1. Reticular Formation – involved in patterns of behaviour such as walking, sleeping and other reflexes 2. Cluster of neurons with dopamine, serotonin, NE receptors,

Reticular Formation Reticular activating system (RAS) • Complex network of nuclei and fibers that extend the length of the brain. • Arouses cerebrum via the thalamus causing alertness. • Also involved in filtering out unnecessary sensory stimuli (e. g. , studying while the TV is on) • Inactive RAS causes sleep

Hind brain – brain stem, most ancient (Metencephalon, Myencephalon) Medulla Oblongata – breathing, other reflexes Cerebellum – coordinated motor movement Pons - cluster of neural fibres, bridge to midbrain, surrounding reticular formation, monitors sleep and arousal in autonomic Involved in alertness and in monitoring basic survival functions such as breathing, heartbeat, and blood pressure. It is also known as the "reptilian brain" because it is considered the entire brain of reptiles.

Medulla oblongata (Myencephalon) • Regulates heartbeat, breathing, and blood pressure • Contains reflex centres for vomiting, coughing, sneezing, hiccupping, and swallowing

UNIT B Chapter 12: Nervous System The Cerebellum (metencephalon) The cerebellum is located under the occipital lobe of the cerebrum. TO PREVIOUS SLIDE Section 12. 3

UNIT B Chapter 12: Nervous System Section 12. 3 Cerebellum Structure and Function • Two portions: white matter covered by thin layer of grey matter • Involved in maintaining posture and balance o Receives sensory input from eyes, ears, joints, muscles, and other sensory pathways about the position of body parts o Receives motor output from the cerebral cortex about where body parts should be located • Involved in producing smooth, coordinated voluntary movements (e. g. , playing piano, hitting a baseball) • Learning new motor skills (playing piano). TO PREVIOUS SLIDE

UNIT B Chapter 12: Nervous System Section 12. 3 Pons “bridge” (metencephalon) • Contains bundles of axons that relay messages between cerebellum and the rest of the CNS • Functions with medulla oblongata to regulate breathing heartbeat and vasoconstriction. • Key role in sleep and dreaming TO PREVIOUS SLIDE

What of the following activities would be hard to do if a person had an injured cerebellum? 1) Running in a race or marathon. 2) Talking and listening to a friend. 3) Playing baseball in the park. 4) Swimming or diving in a pool. 5) Singing a song out loud

1 7 5 3 Higher Mental Functioning Memory and Learning Memory is the ability to hold a thought in mind or recall events from the past. Learning takes place when we retain and utilize past memories.

1 7 5 4 Types of Memory Short-term memory involves activity in prefrontal area. Long-term memory includes semantic memory (numbers, words, etc. ) and episodic memory (persons, events, etc. ). Skill memory involves all motor areas of the cerebrum below the level of consciousness. Eg ability to ride a bike

1 7 5 5 Long-term Memory Storage and Retrieval Long-term memories are stored in bits and pieces throughout the sensory association areas of the cerebral cortex. • visions stored in visual association area • sounds stored in auditory association area The hippocampus is a bridge between sensory association areas and the prefrontal area where memories are utilized. The amygdala associates danger with sensory stimuli.

1 7 5 6 Long-term memory circuits

1 7 5 7 Long-Term Potentiation Long-term potentiation is increased response at synapses within the hippocampus and is essential to long-term memory. However, a postsynaptic neuron in the hippocampus can become too excited and then die. Excitotoxicity, a form of cell death, is due to the neurotransmitter glutamate rushing in too quickly.

1 7 5 8 Language and speech

1 7 5 9 Language and Speech Language and speech are dependent upon Broca’s area (a motor speech area) and Wernicke’s area (a sensory speech area) that are involved in communication. These two areas are located only in the left hemisphere; the left hemisphere functions in language in general and not just in speech.

Which hemisphere is being used? Drawing a picture of an imaginary castle. 2) Doing your math homework. 3) Daydreaming when you should be studying! 4) Talking to a friend. 5) Listening to a parent or teacher.

Brain Dissection Human Brain dissection video https: //www. youtube. com/watch? v=x. B 7 r. Xw_3 g. VY Sheep brain https: //www. biologycorner. com/anatomy/sheepbrain/sheep_disse ction. html