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14.1) Nervous control in humans
Co-ordination is the way all the organs and systems of the body are made to work efficiently together.
A nerve impulse is an electrical signal that passes along nerve cells called neurons.
The human nervous system consists of:
- the central nervous system (CNS) – the brain and spinal cord
- the peripheral nervous system – nerve cells that carry information to or from the CNS
Nerve cells are also called neurons. They are adapted to carry electrical impulses from one place to another:
- The axon is an extended cymiddlelasm thread along which electrical impulses travel.
- Axons are coated by a layer of myelin called myelin sheath, this is an electrically insulating layer which is essential for the proper functioning of the nervous system.
- Dendrite’s function is to pick up electrical impulses from other cells.
- Motor end plate passes the electrical impulses from the neurone to the muscle fibres.
Sensory Neurones: carry electrical impulses in the direction different to that of motor neurones, from the receptors to the CNS.
Motor Neurone: Transmits electrical impulses from the Central nervous system to the effectors.
Relay Neurone: Relay neurones are located in the CNS. Their job is to pass electrical impulses from the sensory neurone onto the motor neurone, so it acts like a diversion.
A reflex action is the means of automatically and rapidly integrating and coordinating stimuli with the responses of effectors. (muscles and glands)
A well-known reflex is the knee-jerk reflex.
- Receptor in the skin detects a stimulus (the change in temperature).
- Sensory neurone sends impulses to relay neurone.
- Motor neurone sends impulses to effector.
- Effector produces a response (muscle contracts to move hand away).
Voluntary and involuntary actions:
The reflex arc is a reflex action. Reflex means it is automatically done without your choice. This is because when the electrical impulses reach the relay neurone in the CNS from the receptors, some impulses are carried by other neurons to the brain, and some impulses are passed onto the motor neurone to the effector muscle and the response takes place. The electrical impulses going to your brain are much slower that the ones going to the effector muscle directly. This is why the reflex action takes place before you realise it, it is uncontrollable.
Reflex actions are said to be involuntary actions. Involuntary actions start at the sense organ heading to the effector. They are extremely quick.
Voluntary actions are the ones that you make the choice to do. Like picking up a bag from the floor for example. Your brain sends electrical impulses to the effector muscles ordering them to contract so you could pick the bag up. Voluntary actions are slower than involuntary actions and they start at the brain.
Synapse: is a junction between two neurones.
- When an impulse arrives at the synapse, vesicles in the cytoplasm release a tiny amount of the neurotransmitter
- It rapidly diffuses across the gap (aka synaptic cleft) and binds with neurotransmitter receptor molecules in the membrane of the neuron on the other side of the synapse.
- This then sets off an impulse in the neurone.
- Sometimes several impulses have to arrive at the synapse before enough transmitter substance is released to cause an impulse to be fired off in the next eurone.
- Synapses control the direction of impulses because neurotransmitter substances are only synthesised on one side of the synapse, while receptor molecules are only present on the other side.
- They slow down the speed of nerve impulses slightly because of the time taken for the chemical to diffuse across the synaptic gap.
- Many drugs produce their effects by interacting with receptor molecules at synapses.
Heroin, stimulates receptor molecules in synapses in the brain, triggering the release of dopamine (a neurotransmitter), which gives a short-lived ‘high’.
Welcome to Anatomy and Physiology, an OpenStax resource. This textbook was written to increase student access to high-quality learning materials, maintaining highest standards of academic rigor at little to no cost.
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About Anatomy and Physiology
Coverage and Scope
The units of our Anatomy and Physiology textbook adhere to the scope and sequence followed by most two-semester courses nationwide. The development choices for this textbook were made with the guidance of hundreds of faculty who are deeply involved in teaching this course. These choices led to innovations in art, terminology, career orientation, practical applications, and multimedia-based learning, all with a goal of increasing relevance to students. We strove to make the discipline meaningful and memorable to students, so that they can draw from it a working knowledge that will enrich their future studies.
Unit 1: Levels of Organization
Chapters 1–4 provide students with a basic understanding of human anatomy and physiology, including its language, the levels of organization, and the basics of chemistry and cell biology. These chapters provide a foundation for the further study of the body. They also focus particularly on how the body’s regions, important chemicals, and cells maintain homeostasis.
Chapter 1 An Introduction to the Human Body
Chapter 2 The Chemical Level of Organization
Chapter 3 The Cellular Level of Organization
Chapter 4 The Tissue Level of Organization
Unit 2: Support and Movement
In Chapters 5–11, students explore the skin, the largest organ of the body, and examine the body’s skeletal and muscular systems, following a traditional sequence of topics. This unit is the first to walk students through specific systems of the body, and as it does so, it maintains a focus on homeostasis as well as those diseases and conditions that can disrupt it.
Chapter 5 The Integumentary System
Chapter 6 Bone and Skeletal Tissue
Chapter 7 The Axial Skeleton
Chapter 8 The Appendicular Skeleton
Chapter 9 Joints
Chapter 10 Muscle Tissue
Chapter 11 The Muscular System
Unit 3: Regulation, Integration, and Control
Chapters 12–17 help students answer questions about nervous and endocrine system control and regulation. In a break with the traditional sequence of topics, the special senses are integrated into the chapter on the somatic nervous system. The chapter on the neurological examination offers students a unique approach to understanding nervous system function using five simple but powerful diagnostic tests.
Chapter 12 Introduction to the Nervous System
Chapter 13 The Anatomy of the Nervous System
Chapter 14 The Somatic Nervous System
Chapter 15 The Autonomic Nervous System
Chapter 16 The Neurological Exam
Chapter 17 The Endocrine System
Unit 4: Fluids and Transport
In Chapters 18–21, students examine the principal means of transport for materials needed to support the human body, regulate its internal environment, and provide protection.
Chapter 18 Blood
Chapter 19 The Cardiovascular System: The Heart
Chapter 20 The Cardiovascular System: Blood Vessels and Circulation
Chapter 21 The Lymphatic System and Immunity
Unit 5: Energy, Maintenance, and Environmental Exchange
In Chapters 22–26, students discover the interaction between body systems and the outside environment for the exchange of materials, the capture of energy, the release of waste, and the overall maintenance of the internal systems that regulate the exchange. The explanations and illustrations are particularly focused on how structure relates to function.
Chapter 22 The Respiratory System
Chapter 23 The Digestive System
Chapter 24 Nutrition and Metabolism
Chapter 25 The Urinary System
Chapter 26 Fluid, Electrolyte, and Acid–Base Balance
Unit 6: Human Development and the Continuity of Life
The closing chapters examine the male and female reproductive systems, describe the process of human development and the different stages of pregnancy, and end with a review of the mechanisms of inheritance.
Chapter 27 The Reproductive System
Chapter 28 Development and Genetic Inheritance
Pedagogical Foundation and Features
Anatomy and Physiology is designed to promote scientific literacy. Throughout the text, you will find features that engage the students by taking selected topics a step further.
- Homeostatic Imbalances discusses the effects and results of imbalances in the body.
- Disorders showcases a disorder that is relevant to the body system at hand. This feature may focus on a specific disorder or a set of related disorders.
- Diseases showcases a disease that is relevant to the body system at hand.
- Aging explores the effect aging has on a body’s system and specific disorders that manifest over time.
- Career Connections presents information on the various careers often pursued by allied health students, such as medical technician, medical examiner, and neurophysiologist. Students are introduced to the educational requirements for and day-to-day responsibilities in these careers.
- Everyday Connections tie anatomical and physiological concepts to emerging issues and discuss these in terms of everyday life. Topics include “Anabolic Steroids” and “The Effect of Second-Hand Tobacco Smoke.”
- Interactive Links direct students to online exercises, simulations, animations, and videos to add a fuller context to core content and help improve understanding of the material. Many features include links to the University of Michigan’s interactive WebScopes, which allow students to zoom in on micrographs in the collection. These resources were vetted by reviewers and other subject matter experts to ensure that they are effective and accurate. We strongly urge students to explore these links, whether viewing a video or inputting data into a simulation, to gain the fullest experience and to learn how to search for information independently.
Dynamic, Learner-Centered Art
Our unique approach to visuals is designed to emphasize only the components most important in any given illustration. The art style is particularly aimed at focusing student learning through a powerful blend of traditional depictions and instructional innovations.
Much of the art in this book consists of black line illustrations. The strongest line is used to highlight the most important structures, and shading is used to show dimension and shape. Color is used sparingly to highlight and clarify the primary anatomical or functional point of the illustration. This technique is intended to draw students’ attention to the critical learning point in the illustration, without distraction from excessive gradients, shadows, and highlights. Full color is used when the structure or process requires it (for example, muscle diagrams and cardiovascular system illustrations).
By highlighting the most important portions of the illustration, the artwork helps students focus on the most important points without overwhelming them.
Micrograph magnifications have been calculated based on the objective provided with the image. If a micrograph was recorded at 40×, and the image was magnified an additional 2×, we calculated the final magnification of the micrograph to be 80×.
Please note that, when viewing the textbook electronically, the micrograph magnification provided in the text does not take into account the size and magnification of the screen on your electronic device. There may be some variation.
These glands secrete oils that lubricate and protect the skin. LM × 400. (Micrograph provided by the Regents of University of Michigan Medical School © 2012)
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About the Authors
Senior Contributing Authors
J. Gordon Betts, Tyler Junior College
Peter Desaix, University of North Carolina at Chapel Hill
Eddie Johnson, Central Oregon Community College
Jody E. Johnson, Arapahoe Community College
Oksana Korol, Aims Community College
Dean Kruse, Portland Community College
Brandon Poe, Springfield Technical Community College
James A. Wise, Hampton University
Mark Womble, Youngstown State University
Kelly A. Young, California State University, Long Beach
Kim Aaronson, Aquarius Institute Triton College
Lopamudra Agarwal, Augusta Technical College
Gary Allen, Dalhousie University
Robert Allison, McLennan Community College
Heather Armbruster, Southern Union State Community College
Timothy Ballard, University of North Carolina Wilmington
Matthew Barlow, Eastern New Mexico University
William Blaker, Furman University
Julie Bowers, East Tennessee State University
Emily Bradshaw, Florida Southern College
Nishi Bryska, University of North Carolina, Charlotte
Susan Caley Opsal, Illinois Valley Community College
Boyd Campbell, Southwest College of Naturopathic Medicine and Health Sciences
Ann Caplea, Walsh University
Marnie Chapman, University of Alaska, Sitka
Barbara Christie-Pope, Cornell College
Kenneth Crane, Texarkana College
Maurice Culver, Florida State College at Jacksonville
Heather Cushman, Tacoma Community College
Noelle Cutter, Molloy College
Lynnette Danzl-Tauer, Rock Valley College
Jane Davis, Aurora University
AnnMarie DelliPizzi, Dominican College
Susan Dentel, Washtenaw Community College
Pamela Dobbins, Shelton State Community College
Patty Dolan, Pacific Lutheran University
Sondra Dubowsky, McLennan Community College
Peter Dukehart, Three Rivers Community College
Ellen DuPré, Central College
Elizabeth DuPriest, Warner Pacific College
Pam Elf, University of Minnesota
Sharon Ellerton, Queensborough Community College
Carla Endres, Utah State University - College of Eastern Utah: San Juan Campus
Myriam Feldman, Lake Washington Institute of Technology Cascadia Community College
Greg Fitch, Avila University
Lynn Gargan, Tarant County College
Michael Giangrande, Oakland Community College
Chaya Gopalan, St. Louis College of Pharmacy
Victor Greco, Chattahoochee Technical College
Susanna Heinze, Skagit Valley College
Ann Henninger, Wartburg College
Dale Horeth, Tidewater Community College
Michael Hortsch, University of Michigan
Rosemary Hubbard, Marymount University
Mark Hubley, Prince George's Community College
Branko Jablanovic, College of Lake County
Norman Johnson, University of Massachusetts Amherst
Mark Jonasson, North Arkansas College
Jeff Keyte, College of Saint Mary
William Kleinelp, Middlesex County College
Leigh Kleinert, Grand Rapids Community College
Brenda Leady, University of Toledo
John Lepri, University of North Carolina, Greensboro
Sarah Leupen, University of Maryland, Baltimore County
Lihua Liang, Johns Hopkins University
Robert Mallet, University of North Texas Health Science Center
Bruce Maring, Daytona State College
Elisabeth Martin, College of Lake County
Natalie Maxwell, Carl Albert State College, Sallisaw
Julie May, William Carey University
Debra McLaughlin, University of Maryland University College
Nicholas Mitchell, St. Bonaventure University
Shobhana Natarajan, Brookhaven College
Phillip Nicotera, St. Petersburg College
Mary Jane Niles, University of San Francisco
Ikemefuna Nwosu, Parkland College Lake Land College
Betsy Ott, Tyler Junior College
Ivan Paul, John Wood Community College
Aaron Payette, College of Southern Nevada
Scott Payne, Kentucky Wesleyan College
Cameron Perkins, South Georgia College
David Pfeiffer, University of Alaska, Anchorage
Thomas Pilat, Illinois Central College
Eileen Preston, Tarrant County College
Mike Pyle, Olivet Nazarene University
Robert Rawding, Gannon University
Jason Schreer, State University of New York at Potsdam
Laird Sheldahl, Mt. Hood Community College
Brian Shmaefsky, Lone Star College System
Douglas Sizemore, Bevill State Community College
Susan Spencer, Mount Hood Community College
Cynthia Standley, University of Arizona
Robert Sullivan, Marist College
Eric Sun, Middle Georgia State College
Tom Swenson, Ithaca College
Kathleen Tallman, Azusa Pacific University
Rohinton Tarapore, University of Pennsylvania
Elizabeth Tattersall, Western Nevada College
Mark Thomas, University of Northern Colorado
Janis Thompson, Lorain County Community College
Rita Thrasher, Pensacola State College
David Van Wylen, St. Olaf College
Lynn Wandrey, Mott Community College
Margaret Weck, St. Louis College of Pharmacy
Kathleen Weiss, George Fox University
Neil Westergaard, Williston State College
David Wortham, West Georgia Technical College
Umesh Yadav, University of Texas Medical Branch
Tony Yates, Oklahoma Baptist University
Justin York, Glendale Community College
Cheri Zao, North Idaho College
Elena Zoubina, Bridgewater State University Massasoit Community College
Shobhana Natarajan, Alcon Laboratories, Inc.
OpenStax wishes to thank the Regents of University of Michigan Medical School for the use of their extensive micrograph collection. Many of the UM micrographs that appear in Anatomy and Physiology are interactive WebScopes, which students can explore by zooming in and out.
We also wish to thank the Open Learning Initiative at Carnegie Mellon University, with whom we shared and exchanged resources during the development of Anatomy and Physiology.
What does this mean for a person with persistent pain?
In acute pain (such as hitting your thumb with a hammer), the brain produces pain ‘alarm signals’ warning us of damage to our body: this is a helpful alarm and is designed to protect us and favour healing. This is good biological design that helps us to survive. The brain and nervous system have evolved over millions of years to amplify and memorise these alarm signals so we don’t ignore them and to link them with any associated surrounding danger. This is where the context of the alarm can become important: what position was I in when I hurt myself? I remember that the stove is hot and if I touch it, I can get a burn. People born with the rare condition of pain insensitivity die at a young age because they don’t realize they’ve been injured until it’s too late.
However, in people with persistent pain, the brain and nervous system can go into overdrive and become super-sensitive—this kind neuroplasticity is called ‘central sensitisation’ (or ‘wind-up’) 5 . The immune system is also thought to be involved in this process 6 .
A super-sensitive nervous system and immune cells (called ‘glia’) release chemicals which ‘turn up the volume’, increasing the number of connections and signals whizzing around in the brain and spinal cord. Because of this ‘turned up volume’, pain may be felt during activities and movements that should not normally provoke pain. Pain may even be felt without moving but just by thoughts alone. Sometimes pain may also spread to other parts of the body.
In people with persistent pain, central sensitization means the alarm ‘keeps on ringing’ and that pain ‘memories’ can persist long after the original cause of the pain has healed. People experiencing persistent pain can experience a memory or ‘echo’ of their original pain. This explains why people can experience pain when an x-ray or scan looks ‘normal’, or why a person with an amputated leg feels ‘phantom pain’. All of this doesn’t mean there’s anything wrong with your nervous system if you have persistent pain (there’s no problem with your ‘hardware’): persistent pain is best thought of as a glitch in the ‘software programme’ that processes danger signals in the body and which the brain interprets as pain. Sometimes this happens along with memory of the original injury or event that caused pain, and these memories become intertwined. For example, you might experience fear and pain with a certain movement.
The good news is that pain management can use helpful neuroplasticity to help re-programme the way the nervous system responds to danger signals and how the brain interprets this as pain 4 . The aim of pain treatments is to reduce central sensitization, decrease pain, favour normal movement and daily activity and restore well-being. Examples of using this plasticity in treatments for persistent pain include using ‘mirror therapy’ to treat phantom leg pain, taking pregabalin (Lyrica™) to decrease nerve sensitivity in nerve-related shingles pain, using mindfulness-based stress reduction (meditation or yoga) to help manage fibromyalgia or re-educating movement without the association of fear. Pain management is all about using helpful neuroplasticity to re-programme and reduce the over-active danger signals in the brain and nervous system. What each individual needs for helpful re-programming may be different and researchers are currently exploring new treatments using plasticity 4 .
Unhelpful neuroplasticity (central sensitisation) is one of the main reasons why people develop persistent pain 2 . Unusual painful sensations called ‘allodynia’ (Greek for ‘other pain’), are common with persistent pain and may include:
- pain caused by normal everyday activities (bending, lifting, sitting, running, playing sport, working)
- pain caused by sensations that don’t normally hurt such as clothes or bed sheets brushing the skin over a painful body area, cold air blowing on a body area (air conditioning), gentle pressure (a hand shake) or movements that are usually pain-free such as back stretches (if you over-stretch an already painful low back, it can REALLY hurt).
Apart from persistent pain, the negative effects of unhelpful neuroplasticity and central sensitization can include: withdrawing from valued activities like work or sports, poor sleep, low energy levels, low mood, negative and unhelpful thoughts, loss of control, increased stress and sickness behaviours, and being less able to care for yourself or others. These responses are not your fault, but are unhelpful when trying to recover from persistent pain, so it is important to seek help to address these issues.
The pain itself can soon become a major and unwelcome focus for our attention. The more concerned and distressed we are about our pain (or our partner’s or child’s pain), especially if we interpret the pain as harmful, the more pain dominates our thinking. In persistent pain it’s almost as if, the more we don’t want pain, the more the brain calls our attention to it.
Course assessments, activities, and outline
UNIT 1: Welcome to CC-OLI Anatomy and Physiology
Module 1: How to Succeed in Anatomy and Physiology
UNIT 2: Introduction to Anatomy and Physiology
Module 2: Anatomy and Physiology Introduction
Quiz: Vital Functions and Body Orientation
Module 3: Introduction of Systems
Quiz: Introduction of Body Systems
UNIT 3: Levels of Organization
Module 4: Levels of Organization IntroductionModule 5: Chemistry
Quiz: Levels of Organization – Chemistry
Quiz: Levels of Organization – Cells
Module 7: Higher Order Structures
Quiz: Levels of Organization – Cells
Module 8: Homeostasis and Feedback Loops
Quiz: Homeostasis and Feedback Loops
Module 9: Homeostatic Maintenance
Quiz: Homeostatic Maintenance
Module 10: Integration of Systems
Quiz: Homeostasis Integration of Systems
Module 11: Skeletal System Introduction
Quiz: Skeletal System Introduction
Module 12: Skeletal Structures and Functions
Quiz: Skeletal Structures and Functions
Module 13: Skeletal Levels of Organization
Quiz: Skeletal Levels of Organization
Module 14: Skeletal Homeostasis
Quiz: Skeletal Homeostasis
Module 15: Skeletal Integration of Systems
Quiz: Skeletal Integration of Systems
Module 16: Muscular System Introduction
Quiz: Muscular System Introduction
Module 17: Muscular Structures and Functions
Quiz: Muscular System: Muscular Structures and Functions
Module 18: Muscular Levels of Organization
Quiz: Skeletal Structures and Functions
Module 19: Muscular Homeostasis
Module 20: Muscular Integration of Systems
UNIT 7: Integumentary System
Module 21: Integumentary System Introduction
Quiz: Integumentary System: Introduction
Module 22: Integumentary Structures and Functions
Quiz: Integumentary System: Integumentary Levels of Organization
Module 23: Integumentary Levels of Organization
Module 24: Integumentary System Homeostasis
Quiz: Integumentary System: Integumentary System Homeostasis
Module 25: Endocrine Structures and Functions
Quiz: Endocrine Structures and Functions
Module 26: Endocrine Levels of Organization
Quiz: Endocrine Levels of Organization
Module 27: Endocrine System Homeostasis and Integration of Systems
Quiz: Endocrine System Homeostasis and Integration of Systems
Quiz: Endocrine System Unit
Module 28: Digestive System Introduction
Module 29: Digestive Structures and Functions
Quiz: Digestive Structures and Functions
Module 30: Digestive Levels of Organization
Quiz: Digestive Levels of Organization
Module 31: Digestive Homeostasis
Quiz: Digestive Homeostasis
Module 32: Digestive System Integration of Systems
Quiz: Digestive System Unit Exam
UNIT 10: Cardiovascular System
Module 33: Cardiovascular System Introduction
Quiz: Cardiovascular System: Introduction
Module 34: Cardiovascular Structures and Functions
Quiz: Cardiovascular System: Structures and Functions
Module 35: Cardiovascular Levels of Organization
Quiz: Cardiovascular System: Levels of Organization
Module 36: Cardiovascular Homeostasis
Quiz: Cardiovascular System: Homeostasis
Module 37: Cardiovascular System Integration of Systems
Quiz: Cardiovascular System: Integration of Systems 1
Quiz: Cardiovascular System: Integration of Systems 2
UNIT 11: Respiratory System
Module 38: Respiratory System Introduction
Module 39: Respiratory Structures and Functions
Quiz: Respiratory Structures and Functions
Module 40: Respiratory Levels of Organization
Quiz: Respiratory Levels of Organization
Module 41: Respiratory Homeostasis
Module 42: Respiratory System Integration of Systems
Module 43: Urinary System Introduction
Module 44: Urinary Structures and Functions
Quiz: Urinary Structures and Functions
Module 45: Urinary Levels of Organization
Quiz: Urinary Levels of Organization
Module 46: Urinary Homeostasis
Module 47: Urinary System Integration of Systems
Module 48: Lymphatic System Introduction
Module 49: Lymphatic Structures and Functions
Quiz: Lymphatic System and Immunity: Structures and Functions
Module 50: Lymphatic Levels of Organization
Quiz: Lymphatic System and Immunity: Levels of Organization
Module 51: Lymphatic Homeostasis
Quiz: Lymphatic System and Immunity: Homeostasis
Module 52: Lymphatic System Integration of Systems
Module 53: Nervous System Introduction
Module 54: Nervous System Structures and Functions
Quiz: Nervous System Structures and Functions
Quiz: Nervous System Structures and Functions
Module 55: Nervous System Levels of Organization
Quiz: Nervous System Levels of Organization
Quiz: Nervous System Levels of Organization
Module 56: The Sensory Functions of the Nervous System
Quiz: Nervous System Sensory Functions
UNIT 15: Review and Synthesis
Module 57: Review and Synthesis
Nervous System Worksheet Answers
i. Add the following labels to the diagram. Axon Myelin sheath Cell body Dendrites Muscle fibres ii. If you like, colour in the diagram as suggested below. Axon - purple Myelin sheath - yellow Cell body - blue Dendrites - green Muscle fibres – red iii. Now indicate the direction that the nerve impulse travels.
2. There are three different kinds of neurone or nerve cell. Match each kind with its function.
to the brain or spinal cord.
or spinal cord to a muscle or gland
3. Match the descriptions in the table below with the terms in the list.
the passage of nerve impulses.
to transmit the nerve impulse across the synapse.
within and outside the body.
4. The diagram below shows a cross-section of the spinal cord. Add the following labels to the diagram.
Central canal White matter Dorsal root Grey matter Ventral root Skin Muscle Sensory neuron Relay neuron Motor neuron Pain receptors in skin
a) List in order the 3 different neurons involved in a reflex arc from the stimulus to the response.
|Stimulus||sensory neuron||relay neuron||motor neuron||Response|
Reflex 1. Blink reflex.
Reflex 2. Paw pinch reflex.
Reflex 3. Swallowing reflex, plus many others.
6. The diagram below shows the nervous system of a horse. Add the following labels.
Brain Spinal cord Cranial nerves Spinal nerves Sciatic nerve Nerves of the autonomic nervous system Vagus nerve Network of nerves to forelimb.
7. Indicate whether the following parts of the nervous system are part
of the Central Nervous System CNS) or the Peripheral Nervous System (PNS).
|Part of nervous system||CNS or PNS?|
|Autonomic nervous system||PNS|
8. The diagram below shows a section of a dog’s brain. Add the labels
in the list below and, if you like, colour in the diagram as suggested.
Cerebellum - blue Spinal cord - green Medulla oblongata - orange Hypothalamus - purple Pituitary gland - red Cerebral hemispheres – yellow.
9. Match the descriptions below with the terms in the list. You may need to use some terms more than once.
10. Match the descriptions below with the parts of the nervous
system in the list. You may need to use some terms more than once.
brain and the spinal cord.
cranial and spinal nerves.
the activity of the heart and smooth muscle.
respiratory rates, increases blood flow to the skeletal muscles and
dilates the pupils of the eye.
and decreases heart and respiratory rates.
11. Name the nerves described below using the choices in the list.
Heterogeneity of neuroblastoma cell identity defined by transcriptional circuitries
Neuroblastoma is a tumor of the peripheral sympathetic nervous system, derived from multipotent neural crest cells (NCCs). To define core regulatory circuitries (CRCs) controlling the gene expression program of neuroblastoma, we established and analyzed the neuroblastoma super-enhancer landscape. We discovered three types of identity in neuroblastoma cell lines: a sympathetic noradrenergic identity, defined by a CRC module including the PHOX2B, HAND2 and GATA3 transcription factors (TFs) an NCC-like identity, driven by a CRC module containing AP-1 TFs and a mixed type, further deconvoluted at the single-cell level. Treatment of the mixed type with chemotherapeutic agents resulted in enrichment of NCC-like cells. The noradrenergic module was validated by ChIP-seq. Functional studies demonstrated dependency of neuroblastoma with noradrenergic identity on PHOX2B, evocative of lineage addiction. Most neuroblastoma primary tumors express TFs from the noradrenergic and NCC-like modules. Our data demonstrate a previously unknown aspect of tumor heterogeneity relevant for neuroblastoma treatment strategies.
'The goal of investigations of brain sexual dimorphism is not to declare a “winner” in some aspect of brain function. It is to elucidate mechanisms of typical and atypical brain development that may guide the search for more effective interventions.' - Giedd, Raznahan, Mills, Lenroot
Santiago Ramon y Cajal, WP
The Journal for Neuroscience, WS
Brain Research through Advanced Innovative Neurotechnologies, Brain Initiative, WP , WS
Center for Sleep and Consciousness, WS
McGovern Institute for Brain Research at MIT, YT
Society for Neuroscience, WS
Brain Map, Allen Institute, WS
The Organization of Behaviour, 1949, Donald Hebb,
The computer and the brain, 1957, John von Neumann, (Silliman Memorial Lectures), PDF , WP , YB
Corticonics: Neural Circuits of the Cerebral Cortex, 1991, M Abeles,
Cortex: Statistics and Geometry of Neural Connectivity, 1991/1998, V Braitenburg, A Schuz,
Brain Sex: The Real Difference Between Men and Women, April 1991, Anne Moir (Author), David Jessel (Author), Lyle Stuart 1st Carol Pub. Group ed edition (April 1991), ISBN-10: 0818405430, ISBN-13: 978-0818405433
Sex Differences In The Brain, Volume 61: The Relation Between Structure And Function (Progress in Brain Research), 15 January 1984, G. J. De Vries, Elsevier Science (15 January 1984), ISBN-10: 044480532X, ISBN-13: 978-0444805324
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Perception is an individual’s interpretation of a sensation. Although perception relies on the activation of sensory receptors, perception happens not at the level of the sensory receptor, but at higher levels in the nervous system, in the brain. The brain distinguishes sensory stimuli through a sensory pathway: action potentials from sensory receptors travel along neurons that are dedicated to a particular stimulus. These neurons are dedicated to that particular stimulus and synapse with particular neurons in the brain or spinal cord.
All sensory signals, except those from the olfactory system, are transmitted though the central nervous system and are routed to the thalamus and to the appropriate region of the cortex. Recall that the thalamus is a structure in the forebrain that serves as a clearinghouse and relay station for sensory (as well as motor) signals. When the sensory signal exits the thalamus, it is conducted to the specific area of the cortex (Figure 17.3) dedicated to processing that particular sense.
How are neural signals interpreted? Interpretation of sensory signals between individuals of the same species is largely similar, owing to the inherited similarity of their nervous systems however, there are some individual differences. A good example of this is individual tolerances to a painful stimulus, such as dental pain, which certainly differ.
Figure 17.3. In humans, with the exception of olfaction, all sensory signals are routed from the (a) thalamus to (b) final processing regions in the cortex of the brain. (credit b: modification of work by Polina Tishina) Scientific Method Connection
The Importance of Homeostasis
The failure of homeostatic regulation in just one body system will cause conditions to deteriorate and it may be fatal. For the health of an organism, all homeostatic regulation mechanisms must function properly. The information below describes how various body systems contribute to overall homeostasis.
The nervous system maintains homeostasis by controlling other parts of the body. It comprises the central nervous system and the peripheral nervous system. The peripheral nerves are those outside of the brain and spinal cord which go to the limbs and organs. The brain and spinal cord make up the central nervous system. The hypothalamus in the brain is particularly important for maintaining homeostasis because it controls the actions of the medulla oblongata (involuntary functions), the autonomic nervous system (smooth muscle and glands), and the pituitary gland (hormone excretion).
This system comprises the glands that excrete hormones into the bloodstream. Hormones have a myriad of functions in the body that maintain homeostasis by targeting certain tissues. Besides regulating bone growth, muscle metabolism, and energy production, there are hormones that regulate fluid balance, the production of red blood cells, blood pressure, and inflammation.
The bones of the skeleton protect the brain, spinal cord, and internal organs and serve as a reservoir of calcium, phosphorous, and other minerals. Calcium, for example, is needed for muscle contraction. Red and white blood cells and other cells of the immune system are made and stored in the bone marrow. The skeleton also makes movement of the body possible which is important for homeostasis. An example of this is when an animal’s core temperature becomes too hot, it can move into the shade of a tree or into the water to cool itself.
Muscles not only work with the skeleton to move the body, but they make digestion and breathing possible. The layers of muscle also protect internal organs and generate heat when they contract (useful for shivering when the body is cold). Finally, the heart is made of cardiac muscle and its pumping of blood is necessary for many of the homeostatic control systems in the body.
This system is key to maintaining homeostasis by controlling blood volume and tissue fluids. The lymphatic system works with the capillaries in the cardiovascular system to remove excess fluid which can build up and cause edema and swelling. The lymphatics are also a critical part of the immune system and immune response. After B cells mature in the bone marrow, they migrate to the lymph nodes where they stand guard against foreign invaders in the body. Other parts of the lymphatic system that help maintain homeostasis are the lymph glands, tonsils, adenoids, spleen, and thymus gland.
The respiratory system transports gases like oxygen and carbon dioxide in and out of the lungs. This is critical to maintaining the proper pH of the blood. If the blood is too acidic, the brain slows the breathing to increase the amount of bicarbonate ions (carbon dioxide) in the blood. Conversely, to adjust the blood chemistry when the pH is too low, respiration increases so that more carbon dioxide is expelled. The respiratory system also acts to dissipate heat when the body temperature gets too hot. This is done through open-mouth breathing or panting in animals that don’t have sweat glands.
The digestive system helps maintain homeostasis by eliminating toxins and waste and supplying nutrients to the body. It also serves the critical immune system function of destroying bacteria and viruses than enter the body through food and water intake. Also, the heat generated during the digestive process contributes to regulation of the core temperature.
The body eliminates nitrogenous waste through urine which is important for maintaining homeostasis in the body. The urinary system also helps control blood pressure by regulating the amount of fluid and ions in the body. Also, the kidneys produce the hormone erythropoietin which stimulates red blood cell production in the bone marrow.