The Nervous system The nerve cell is the basic unit of communication in the vertebrate nervous system

Components of the Nervous System Bio 130 Human Biology Figure 11.1

Three Classes of neurons The Neural circuit consists of Sensory neurons receptor for stimulus Interneuron (CNS) integrate signals Motor neuron transfer signal to effector (muscle) Bio 130 Human Biology

Types of Neurons in the Nervous System Bio 130 Human Biology Figure 11.2

Anatomy of a Neuron Cell body: functional portion Dendrites: short extensions that receive signals Axon: long extension that transmits impulses Bio 130 Human Biology

Figure: 07-02a Title: The structure of a neuron. Caption:

How does a neuron hold and move info? A neuron at rest has a voltage difference across the plasma membrane called a resting voltage potential An action potential (AP) is when this charge across the membrane is briefly switched The action potential moves down the membrane at a rapid pace. Ap can move faster over mylenated portions is called saltatory conduction Bio 130 Human Biology

Myelinated Neuron Bio 130 Human Biology Figure 11.7a

Bio 130 Human Biology

Maintenance of the Resting Membrane Potential Bio 130 Human Biology Figure 11.3

Resting Membrane Potential, Graded Potentials, and an Action Potential Bio 130 Human Biology Figure 11.4

Figure: 07-04 Title: The plasma membrane of a neuron. Caption: The plasma membrane of a neuron contains two types of pathways through which ions can pass.

The Nerve Impulse Is a Bioelectrical Signal The sodium-potassium pump uses ATP to transport sodium ions out and potassium ions in The inside of a resting neuron has a negative charge relative to the outside An action potential is a reversal and restoration of the charge difference across the membrane The sodium-potassium pump restores the original distribution of ions Action potentials are all-or-none events A neuron cannot fire during the refractory period Bio 130 Human Biology

How does a signal move from one neuron to another? A synaptic cleft divides 2 neurons The AP will not move across the synaptic cleft Neuro transmitters are released by the signal cell to the receiver cell Move by diffusion Bio 130 Human Biology

Bio 130 Human Biology

Transfer of Information from Neuron to Target Synaptic transmission: Release of neurotransmitter: graded potential achieved Effects of neurotransmitter: Excitatory: depolarize postsynaptic cell Inhibitory: hyperpolarize postsynaptic cell Role of postsynaptic neuron: integrate and process information Bio 130 Human Biology

Types of chemical synapse Acetylcholine: neuromuscular junctions, glands, brain and spinal cord Norepinepherine: affects brain regions concerned with emotions, dreaming From table 11.1 Bio 130 Human Biology

Figure: 07-08 Title: Synapses are interaction points within the nervous system. Caption: A neuron may have as many as 10,000 synapses. Some synapses have an excitatory effect on the membrane of the postsynaptic neuron and increase the likelihood that the neuron will fire. Other synapses have an inhibitory effect and reduce the likelihood that the postsynaptic neuron will fire. The net effect of all synapses will determine whether an action potential is generated in the postsynaptic neuron.

The nervous System Bio 130 Human Biology

Paths of information flow Signals between the brain and spinal cord move to the body regions by nerves Sensory nerves move a signal towards the brain and spinal cord Motor neurons move a signal from the brain or spinal cord to the body Bio 130 Human Biology

Figure: 08-10 Title: A reflex arc. Caption: A reflex arc consists of a sensory receptor, a sensory neuron, usually at least one interneuron, a motor neuron, and an effector.

Divisions of the nervous System Central nervous system CNS Is the brain and spinal cord Peripheral nervous system PNS all nerves that carry signals to and from the CNS Bio 130 Human Biology

Figure: 08-01 Title: The nervous system. Caption: Although the human nervous system functions as an integrated whole, it is convenient to talk about its functional parts. The brain and spinal cord (shown in blue), form the central nervous system (CNS), which integrates incoming information and directs appropriate responses. Nerves carry information to and from the central nervous system. These nerves, together with collections of nerve cell bodies called ganglia, constitute the peripheral nervous system (PNS). The PNS may be divided into the somatic and the autonomic nervous systems. The somatic nervous system (shown in green) carries sensory information from the skin, skeletal muscles, and joints to the CNS and also directs our voluntary movements, such as those of the arms and legs. The autonomic nervous system (shown in pink) serves as an “automatic pilot" that regulates our involuntary bodily activities

Parts of the PNS Sensory Division carries info to the brain and spinal cord. Motor Division carries info from the brain to the bodies effectors (things that do the work) Bio 130 Human Biology

The Motor division of the PNS has 2 divisions Somatic nerves relay commands to and from skeletal muscle Voluntary control Autonomic nerves send signals to and from smooth muscles Involuntary control Sympathetic Parasympathetic Bio 130 Human Biology

The autonomic divisions Parasympathetic slow down the body activity when the body is not under stress Rest and digest Sympathetic increase overall body activity during times of stress, excitement or danger fight or flight response hormone epinephrine Bio 130 Human Biology

Figure: 08-12 Title: The structure and function of the autonomic nervous system. Caption: Most organs are innervated by fibers from both the sympathetic and the parasympathetic nervous systems. When this dual innervation occurs, the two branches of the autonomic nervous system have opposite effects on the level of activity of that organ. A chain of ganglia links the sympathetic nervous system. It usually acts as a unit, with all its effects occurring together. The ganglia of the parasympathetic nervous system are near the organ serviced. Its effects are more localized. Fig 11.12

Sympathetic and Parasympathetic Are Antagonistic Work towards the automatic, subconscious maintenance of homeostasis. Bio 130 Human Biology

Bio 130 Human Biology

Parts of CNS Figure: 08-09ab Title: The spinal cord. Caption: The spinal cord is a column of neural tissue that is protected by the bones of the vertebral column.

Components of the CNS Spinal cord Brain parts 31 pair of spinal nerves Grey matter White matter Controls some reflex actions like bladder emptying Brain parts Hindbrain medulla oblongata cerebellum pons Midbrain Forebrain cerebrum thalamus hypothalamus Bio 130 Human Biology

Figure: 08-02 Title: Protecting the central nervous system. Caption: The central nervous system is protected by the meninges, the cerebrospinal fluid, and the bones of the skull and vertebral column.

Ventricles of the Brain and Circulation of Cerebrospinal Fluid Bio 130 Human Biology Figure 11.13

Brain: Major Divisions Hindbrain: coordinates basic, automatic, vital functions Medulla oblongata: controls automatic functions of internal organs Cerebellum: coordinates basic movements Pons: aids flow of information Midbrain: coordinates muscles related to vision and hearing Bio 130 Human Biology

Brain: Processes and Acts on Information Forebrain: receives and integrates information concerning emotions and conscious thought Hypothalamus: helps regulate homeostasis Thalamus: receiving, processing, and transfer center Limbic system: neuronal pathways involved in emotions and memory Cerebrum/cerebral cortex: higher functions Bio 130 Human Biology

Sleep Sleep center: reticular activating system (RAS) Stages: based on electroencephalograms (EEGs): Stage 1: transitional, random small waves on EEG Stage 2: skeletal muscles relax, little eye or body movement, EEG shows sleep spindles Bio 130 Human Biology

Sleep (cont.) Stage 3: heart and respiration slower, EEG shows slow wave sleep Stage 4: difficult to awaken, heart and respiration slowest, body temperature decreased REM (rapid eye movement) sleep: dreaming, EEG same as awake Bio 130 Human Biology

Limbic System: Emotions of Fear, Anger, Sorrow, Love Bio 130 Human Biology Figure 11.19

Memory: Storing and Retrieving Information Short term: working memory, information from previous few hours Long term: information from previous days to years Bio 130 Human Biology

Other parts of the CNS The two cerebral hemispheres communicate through the corpus collosum left verbal skills right nonverbal skills such as music math, abstract Brain cavities and Canals cerebrospinal fluid surrounds and fills in cavities in the brain Blood Brain barrier- controls what moves into the brain. Will prevent infections. Bio 130 Human Biology

Our state of consciousness The CNS governs sleeping, dozing, daydreaming and full alertness neurons of the reticular activating system RAS control the changing levels of consciousness by releasing serotonin. Bio 130 Human Biology

Memory Association is the linkage of information to structural and chemical changes short term- few bits lasts a couple of hours Long term- permanent and limitless The most important info goes rapidly into long term storage memory is stored in a form resistant to degradation Possibly caused by changes in synapses. Bio 130 Human Biology

Tips on studying Concentrate on what you study. Minimize interference. Study takes time. Break material into smaller portions. Rephrase materials in your own words. Test yourself to see what you know. Bio 130 Human Biology

Primary somatosensory and motor areas of cerebral cortex Figure: 08-07 Title: Primary motor and primary somatosensory regions of the cerebral cortex. Caption: The primary motor and the primary somatosensory regions of the cerebral cortex are meticulously arranged, with each area corresponding to a particular part of the body. The general arrangement is similar in the two regions. However, the amount of sensory cortex devoted to each body part increases with the degree of sensitivity of that part. The largest portions of the cerebral motor cortex are devoted to the body parts over which we have the greatest degree of motor control. Primary somatosensory and motor areas of cerebral cortex

Disorders of the nervous system Trauma Infections Transmission and synaptic defects. Abnormal growth Headache Tumors Stroke Bio 130 Human Biology

Psychoactive Drugs Action: affects higher brain functions Psychological dependence: user craves the feeling associated with the drug Tolerance: takes more of the substance to achieve the same affect Addiction: the need to continue obtaining and using a substance; no free choice Withdrawal: physical symptoms that occur upon stopping the drug Bio 130 Human Biology

Know what the parts of the brain do Brain parts medulla oblongata cerebellum pons cerebrum thalamus hypothalamus Bio 130 Human Biology

Bio 130 Human Biology

Bio 130 Human Biology

seratonin Bio 130 Human Biology

Just a reminder to talk about drugs that interact with brain. Bio 130 Human Biology