Nervous system and coordination brian & friends para 4to

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Nervous system and coordination brian & friends para 4to

  1. 1. NERVOUS SYSTEM AND COORDINATION
  2. 2. Sensitivity Ability to detect STIMULI and react to them Useless to an organism unless it can respond to them in some useful way RECEPTORS  pick up the stimuli (pain or receptors) chemical EFFECTORS like MUSCLES and GLANDS A COMMUNICATION/ COORDINATION SYSTEM
  3. 3. Receptors groups of specialised cells. They can *detect changes in the environment (stimuli) *turn them into electrical impulses. Receptors are often located in the sense organs such as the ear, eye and skin Receptors often located in the sense organs such as the ear, eye and skin Sense organs Skin Tongue Nose Eyes Ears Effectors parts of the body that produce a response. Here are three examples: 1.a muscle contracting to move an arm 2.a muscle squeezing saliva from the salivary gland 3.a gland releasing a hormone into the blood Receptors sensitive to touch, pressure, pain and temperature chemicals in food chemicals in the air light sound and position of the head
  4. 4. Most animals have 2 methods of sending messages from RECEPTORS to EFFECTORS Nervous System Endocrine System Receptors, nerves and neurons Secretory cells ELECTRICAL impulses along the nerves faster Effect of the message only lasts a very short while Chemicals called HORMONES transported by the bloodstream to target organs Slower Effect of the message lasts longer
  5. 5. NERVOUS SYSTEM a system of organs working together to detect and respond to stimuli. made up of two systems, the Central Nervous System (C.N.S) and the Peripheral Nervous System (P.N.S) connects the central nervous system to the other parts of the body Central Nervous System (CNS) the processing center for the nervous system. It receives information from and sends information to the peripheral nervous system. The two main organs of the CNS are the brain and spinal cord. The brain processes and interprets sensory information sent from the spinal cord
  6. 6. Components of the Nervous System  Central Nervous System Social – Brain and Spinal Cord life  Peripheral Nervous System – Cranial and Spinal nerves  Autonomic Nervous Vegetative System – life parasympathetic and sympathetic
  7. 7. The human nervous system. The brain and spinal cord form together the CENTRAL NERVOUS SYSTEM. Nerves carry electrical impulses, from the central nervous system to all parts of the body  EFFECTORS (muscles and glands) go into action when they receive nerve impulses MOTOR IMPULSES Nerves carry electrical impulses BACKto the CNS from RECEPTORS in the sense organs the nerve impulses SENSORY IMPULSES
  8. 8. Nerve impulses from the sense organs (skin, eye, ears) to the central nervous system are called SENSORY IMPULSES. This is the way by which information from the peripheral receptors travel to the central nervous system. From the central nervous system, this impulses are carried to the EFFECTORS, resulting in action. These are called MOTOR IMPULSES.
  9. 9.  There are millions of neurons, which form the electrical connections that let us think.  Dendrite  Fine hair-like extensions on the end of a neuron. Function: receive incoming stimuli. Cell Body or Soma  The center of the neuron, containing the nucleus and the organelles  Function: Directs impulses from the dendrites to the axon. Nucleus  Control center Axon Pathway for the nerve impulse (electrical message) from the soma to the opposite end of the neuron. Some of them can reach a length of up to a metre in humans Myelin Sheath  An insulating layer around an axon (composed mainly of fat) letting the signal travel about 100 times faster than in an unmyelinated axon It is made up of Schwann cells.. Nodes of Ranvier  Gaps between schwann cells.  Function: Saltatory Conduction (Situation where speed of an impulse is greatly increased by the message ‘jumping’ the gaps in an axon).       
  10. 10. Types of Neurons
  11. 11. NEURONES. The central nervous system, and the peripheral nerves are made up of neurones. MOTOR NEURONE Carry impulses from the central nervous system to the muscles. MULTI POLAR NEURONES Are neither sensory nor motor but make connections to other neurones inside the central nervous system. SENSORY NEURONES Carry impulses from the sense organs to the central nervous system.
  12. 12. Automatic response to a stimulus REFLEX Pupillary reflex The brain is informed but you don’t waste time thinking about what to do Plantar reflex Achiles reflex Knee jerk Reflexes can be divided into: -innate/primitive -acquired
  13. 13. Passes the message on to the brain The brain is informed but you don’t waste time thinking about what to do We need to inform the CNS to allow a variety of behaviours under different circumstances
  14. 14. Reflex arc Dorsal root (SENSORY fibres) Ventral root (MOTOR fibres)
  15. 15. It is necessary for impulses to pass from one Synapse neurone to another. The regions where impulses are able to cross from one neurone to the next are called SYNAPSES. At a synapse a branch at the end of one fibre is in close contact with a dendrite of another neurone. When an impulse arrives at the synapse, it releases a tiny amount of a chemical substance called a NEUROTRANSMITTER SUBSTANCE, which sets off an impulse in the next neurone. (relay neurone) SYNAPSES ensure that nervous impulses only travel in
  16. 16. Sensory neurone Relay neurone
  17. 17. The NERVE IMPULSE The impulse is a series of electrical pulses, which travel down the fibre. All the impulses are similar. The difference is that each impulse is sent to different parts of the brain. For example, the nerves from the eye go to the part of the brain concerned with sight. Then the brain recognizes that the impulses comes from the eye and we SEE something.
  18. 18. *receives sensory impulses *sends motor impulses to glands and muscles *correlates the stimuli and the memory *stores information so as to modify behaviour *co ordinates the mechanisms and chemical reactions the body works efficiently
  19. 19. The Triune Brain  Neocortex - Thought (including planning, language, logic & will, awareness)  Limbic System - Emotion (feelings, relationship/nurturing, images and dreams, play)  Reptilian Brain - Instinct (survival, breathing/swallowing/h eartbeat, startle response) Three Brains in One
  20. 20. Sensory information such as vision, smell and hearing processed here. Higher cognitive functions. cerebral cortex hypothalamus Homeostasis: control of body temperature and osmoregulation. Secretes hormones pituitary gland Produces hormones that control growth, sexual development and metabolism midbrain Involved in control of visual and auditory systems. Also controls body movement corpus collosum Connects the left and right hemispheres to coordinate information cerebellum Fine motor control, posture and balance pons Links the medulla with the thalamus medulla oblongata Controls breathing, heart rate and blood pressure; reflex actions such as vomiting and sneezing
  21. 21. External Brain Structures
  22. 22. The Cerebrum The largest portion of the brain is the cerebrum. It consists of two hemispheres that are connected together at the corpus callosum. The cerebrum is often divided into five lobes that are responsible for different brain functions. Corpus callosum
  23. 23. The Cerebrum Neocortex (Multipolar neurones) The cerebrum’s surface—the neocortex—is convoluted into hundreds of folds. The neocortex is where all the higher brain functions take place.
  24. 24. Lobes of the Cerebrum Limbic Lobe Frontal Lobe Parietal Lobe Occipital Lobe Temporal Lobe
  25. 25. Frontal Lobe The frontal lobe is the area of the brain responsible for higher cognitive functions. These include: • • • • • • • • Problem solving Spontaneity Memory Language Motivation Judgment Impulse control Social and sexual behavior.
  26. 26. Temporal Lobe The temporal lobe plays a role in emotions, and is also responsible for smelling, tasting, percepti on, memory, understandi ng music, aggressiveness, a nd sexual behavior. The temporal lobe also contains the language area of the brain.
  27. 27. Parietal Lobe The parietal lobe plays a role in our sensations of touch, smell, and taste. It also processes sensory and spatial awareness, and is a key component in eye-hand co-ordination and arm movement. The parietal lobe also contains a specialized area called Wernicke’s area that is responsible for matching written words with the sound of spoken speech.
  28. 28. Occipital Lobe The occipital lobe is at the rear of the brain and controls vision and recognition.
  29. 29. Limbic Lobe The limbic lobe is located deep in the brain, and makes up the limbic system. area of the brain that regulates emotion and memory. It directly connects the lower and higher brain functions. A. Cingulate gyrus B. Fornix C. Anterior thalamic nuclei D. Hypothalamus E. Amygdaloid nucleus F. Hippocampus
  30. 30. The cerebellum is connected to the brainstem, and it is the center for body movement and balance. It receives sensory impulses from – muscles - semicircular canals - utriculus Cerebellum
  31. 31. Thalamus Thalamus means ―inner room‖ in Greek, as it sits deep in the brain at the top of the brainstem. The thalamus is called the gateway to the cerebral cortex, as nearly all sensory inputs pass through it to the higher levels of the brain.
  32. 32. Hypothalamus The hypothalamus sits under the thalamus at the top of the brainstem. Although the hypothalamus is small, it controls many critical bodily functions: • Controls autonomic nervous system • Center for emotional response and behavior • Regulates body temperature • Regulates food intake • Regulates water balance and thirst • Controls sleep-wake cycles • Controls endocrine system The hypothalamus is shaded blue. The pituitary gland extends from the hypothalamus.
  33. 33. The Brainstem The brainstem is the most primitive part of the brain and controls the basic functions of life: breathing, heart rate, swallowing, reflexes to sight or sound, sweating, blood pressure, sleep, and balance. The brainstem can be divided into three major sections.
  34. 34. The divisions of the brain are seen here in a Frontal (Coronal) Slice of the brain. 1- Cerebrum 2- Thalamus 3- Mesencephalon - Midbrain 4- Pons 5- Medulla oblongata 6- Medulla spinalis - Spinal cord
  35. 35. The Medulla Oblongata (=BULBO RAQUIDEO) The medulla oblongata merges seamlessly with the spinal cord and creates the base of the brainstem. The medulla is primarily a control center for vital involuntary reflexes such as swallowing, vomiting, sneezing, co ughing, and regulation of cardiovascular and respiratory activity. The medulla is also the origin of many cranial nerves.
  36. 36. The Pons (=PROTUBERANCIA) The pons is the rounded brainstem region between the midbrain and the medulla oblongata. In fact, pons means ―bridge‖ in Latin. The main function of the pons is to connect the cerebellum to the rest of the brain and to modify the respiratory output of the medulla. The pons is the origin of several cranial nerves.
  37. 37. The Ventricles The ventricles are a complex series of spaces and tunnels through the center of the brain. The ventricles secrete cerebrospinal fluid, which suspends the brain in the skull. The ventricles also provide a route for chemical messengers that are widely distributed through the central nervous system. Click image to play or pause video
  38. 38. The Meninges •The meninges are layers of tissue that separate the skull and the brain. *Cerebrospinal fluid is a colorless liquid formed within the ventricles of the brain that circulates throughout the central nervous system. *Cerebrospinal fluid fills the ventricles and meninges allowing the brain to ―float‖ within the skull. Skull Dura mater Arachnoid Layer Pia Mater Brain
  39. 39. GREY MATTER: bodies of neurons + dendrites concentrated WHITE MATTER: consists of all the axons PONS MEDULLAOBLONGATA SPINAL CORD  grey matter inside, surrounded by white matter CEREBELLUM CEREBRUM white matter inside, surrounded by grey matter

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