Presentation on theme: "9 How Nerve Signals Maintain Homeostasis"— Presentation transcript:
1 9 How Nerve Signals Maintain Homeostasis 9.1 The Importance of the Nervous SystemPage1
2 9.1: The Importance of the Nervous System The nervous system is an elaborate communication system that has more than 100 billion nerve cells in the brain alone.Memory, learning and language are all a part of the nervous system.Has two divisions: the central nervous system (CNS) and the peripheral nervous system (PNS).
3 Vertebrate Nervous System Central nervous System (CNS):The nerves in the brain and spinal cordPeripheral Nervous System (PNS):Nerves that carry info. Between the organs and the CNS
4 CNS is all the nerves of the brain and spinal cord and is the coordinating centre for incoming and outgoing information.The PNS include the nerves that carry information between the organs of the body and the CNSPNS can be divided further into the somatic and autonomic nerves.Somatic: controls the skeletal muscle, bones and skin.Autonomic: special motor nerves that control the internal organs of the body.Autonomic can be subdivided into the sympathetic and the parasympathetic.
5 Peripheral Nervous System Somatic Nerves:Controls skeletal muscles, bones and skinBrings information from the external environment to the CNSMotor somatic nerves
6 Controls the skeletal muscles What do the somatic nerves control?Controls the skeletal muscles
7 Peripheral Nervous System Autonomic Nerves:Motor nerves that control organs
9 Is this sensory, integrative, or motor input? monitor:temperature, light, and sound, ETC.Inside the body receptors detect variations in:pressure, pH, carbon dioxide concentration, and the levels of various electrolytes.
10 Is this sensory, integrative, or motor input? signals are brought together to:create sensations, to produce thoughts, or to add to memory.Decisions are made based on the sensory input. This is integration.Integrative
11 Is this sensory, integrative, or motor input? nervous system responds by:sending signals to muscles, causing them to contract, or to glands, causing them to produce secretions.muscles and glands are called effectorsthey cause an effect in response to directions from the nervous system.This is the motor output or responsemotor input
12 Anatomy of a Nerve Cell Glial Cells: Structural support and metabolism of nerve cellsNon-conductingNeurons:Sensory neuronsInterneuronsMotor Neurons
13 Sensory Neurons Afferent neurons Sense and relay stimuli (information) from the environment to the CNSLocated in clusters outside of the spinal cord
14 Interneurons/Association Neurons Neurons that link together neurons in the bodyMainly in the spinal cord and brainhuman brain contains ~100 billion (1011) interneurons averaging 1000 synapses on each or some 1014 connections
15 Motor Neurons Efferent Neurons Relay information to the effectors Muscles, organs and glandsThe axons connecting your spinal cord to your foot can be as much as 1 m long (although only a few micrometers in diameter).
16 What are the three parts of all neurons? DendritesThe cell bodyThe axon
18 Neuron Structure Dendrites: Receive information Conduct nerve impulses toward the cell bodyAxon:Sends nerve impulses from the cell body to other neurons (effectors)Myelin Sheath:White coat of fatty protein that covers some axons
19 Neuron Structure Schwann Cells: Individual cells that compose the myelin sheathInsulates the nerve cellNodes of Ranvier:Areas between the sections of myeline sheath
26 What are the 3 overlapping nervous system functions? SensoryIntegrativeMotor
27 Does this describe the autonomic or somatic nervous system? Control the internal organs of the bodyoperate without conscious controlconstant interplay of balance between sympathetic and parasympatheticautonomic nerves
29 increases the release of glucose, Does this describe the sympathetic nervous system or parasympathetic?Prepares the body for stress:increases heart rate,increases the release of glucose,dilates the pupils,increases blood flow to the skin,causes release of epinephrinesympathetic nervous system
30 parasympathetic nervous system Restores normal balance: decreases heart rate,stores glucose,constricts pupils,decreases blood flow to the skin
32 Neuron Repair Neurilemma: Thin membrane that surrounds the axon Promotes regeneration of damaged neuronsNot in all nerve cellsWhite Matter:Nerve cells in the brain that contain myelinated fibres and a neurilemmaGrey Matter:Nerve cells in the brain and spinal cord that lack a myelin sheath and neurilemmaWhy are spinal and brain injuries often permanent?
33 How to Fix “Irreparable” Damage to the CNS Reattach two torn nervesLimited success2. Grafts from the PNSMore successful…CNS cells that are left alone however, had no regeneration
34 Stem Cells Cells that have not specialized into tissue cells Experiments are being done on replacing damaged cells using stem cellsE.g. pp. 415…rats with reconnected spinal cordsPage 417 # 1-6