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Biological basis of behavior (new)
 

Biological basis of behavior (new)

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    Biological basis of behavior (new) Biological basis of behavior (new) Presentation Transcript

    • 1. To be familiar with the different parts of a neuron, as well as it types and functions.2. To be able to trace how neurons communicate with one another.3. To be familiar with different parts of the nervous system and their functions4. To identify parts of the endocrine system and their influence in human behavior
    •  Neurons are the information-processing and information- transmitting element of the nervous system They come in different shapes They may also be classified according to their major functions
    •  Sensory neurons - They gather information from the environment and transmit them to the brain Motor neurons - Those that accomplish movement of the muscles Interneurons - Can be found in the central nervous system; responsible for perceiving, learning, remembering, planning, and deciding among other important neural activities
    •  Soma- Contains the nucleus and other parts that are responsible proving the life processes of the cell. Dendrites- Tree-like structures that serve as the recipient of messages coming from the neighboring neurons. Axon- The axon is a long slender tube, covered by a fatty insulator called the myelin sheath, that carries information from the cell body to the terminal button. Bundles of axons constitute nerves
    •  Terminal Buttons - Knob-like structures at the end of the axon’s twigs. Action potential- brief electrical/ chemical event. The transmission of the messages occurs in the synapse, a junction between the terminal buttons of the sending cell and a portion of the somatic or dendritic membrane of the receiving cell.
    •  Terminal Buttons release chemicals known as neurotransmitters or transmitter substances Neurotransmitters may be classified into two: excitatory or inhibitory
    •  Multipolar neurons Bipolar neuron Unipolar neuron
    • Insert Picture (reflex)
    • Insert Picture (reflex)
    •  A neuron fires an impulse when it receives signals from sense receptors that are stimulated by pressure, heat or light, or when it is simulated by chemical messages from adjacent neurons If these signals exceed a minimum intensity, called the threshold, they trigger an impulse. The impulse, called the action potential, is a brief electrical charge the travels down to the axon.
    •  The neuron’s reaction is an all-or-none response, meaning they either fire or not. A stronger stimulus cannot trigger a stronger or faster impulse, but they can trigger more neuron to fire. When the Action potential reaches the terminals at an axons end, it triggers the release of chemical messengers, called neurotransmitters , onto the synapse – a gap between axons and dendrites of adjacent neurons.
    •  These neurotransmitter molecules cross the synaptic gap and bind to the receptor site on the dendrites of the receiving neuron. This allows electrically charged atoms to enter the receiving neuron and excite or inhibit a new action potential.
    •  Dopamine influences movement, learning, attention, and emotion. Serotonin affects mood, hunger, sleep, and arousal. Norepinephrine helps control alertness and arousal. Gamma-aminobyutric acid (GABA) inhibitory functions and is sometime implicated in eating and sleep disorders. Acetylcholine works on neurons in muscle action, learning and memory. Endorphins are released in response to pain and vigorous exercise.
    •  The nerve impulse can be excitatory; It prompts the adjacent neuron to fire. An impulse can also be inhibitory; it prevents the adjacent neuron to fire
    •  All-or-non law - An action potential either occurs or does not occurs, and is always in constant strength. Rate law - A high rate of firing causes a strong muscular contraction and an intense odor causes a high rate of firing in the axon the serves the nose. Saltatory conduction - action potentials are only conducted in a hopping fashion in the nodes of Ronvier
    •  Reuptake - a rapid removal of neurotransmitter from the synaptic cleft by the terminal buttons Enzymatic deactivation - enzymes destroy some neurotransmitter molecules into its constituents
    •  The rate an axon fires is determined by the relative activity of the excitatory and inhibitory synapses on the soma and dendrites of that cell The interaction of these activities is referred to as neural integration If the activity of the excitatory synapses goes up, the rate of firing will go up. If the activity of inhibitory synapses goes up, the rate of firing will go down
    •  Neuromodulators - chemicals released by neurons in larger amounts and diffused for the longer distances, modulating the activity of many neurons in a particular part of the brain Hormones secreted by endocrine glands Hormones affect the activity of the cells that contain specialized receptors, called target cells Many neurons contain hormone receptors, thus influencing their activity
    •  Anterior or Rostral- front end Posterior or Caudal – the tail Dorsal- the back surface Ventral- front surface Lateral-toward the side Medial- toward the midline Ipsilateral – same side of the body Contralateral- opposite sides of the body Cross section- slice transversely Horizontal section-slice parallel to the ground (the brain) Sagittal section- slice perpendicular to the ground and parallel to the neuroaxis
    • dorsalanterior ventral ventral dorsal posterior
    •  The brain is encased in a skull Floats in a pool of cerebrospinal fluid (CSF) Chemically protected by the blood brain barrier
    •  Dura mater (the hard mother) Archnoid membrane – not found in PNS Pia mater ( pious mother) - contains surface blood vessels and follows the surface convolution of the brain Subarachnoid space - gap filled with cerebrospinal fluid
    • MAJOR DIVISION SUBDIVISION PRINCIPAL STRUCTUREForebrain Telencephalon Cerebrum/ Cerebral cortex Basal ganglia Limbic System Diencephalon Thalamus HypothalamusMidbrain Mesencephalon Tectum/TegmentumHindbrain Metencephalon Cerebellum Pons Myelencephalon Medulla Oblangata
    •  Cerebrum, covered by the cerebral cortex Limbic system Basal ganglia
    •  Two cerebral hemispheres Glia, cell bodies, dendrite, and interconnecting axons of neurons Called the “gray matter” The cerebral hemisphere can be divided into four areas
    • Lobes Regions / AreasFrontal Lobe Primary motor cortex, Motor association cortexParietal Lobe Primary somatosensory cortex, somatosensory association cortexOccipital Lobe Primary visual cortex, Visual association cortexTemporal Lobe Primary auditory cortex, Auditory association cortex
    •  With the exemption for the olfactory sense, all information from the body or the environment is sent to the primary sensory cortex of the contralateral (opposite) hemisphere.
    • Motor
    •  The left hemisphere is concerned with analysis The right hemisphere is specialized for synthesis Two hemispheres are unified by the corpus callosum
    •  Cerebrum, covered by the cerebral cortex Limbic system Basal ganglia
    •  The amygdala is involved in the experience of emotion The hippocampus is involved in learning and memory
    •  Cerebrum, covered by the cerebral cortex Limbic system Basal ganglia
    •  A collection of nuclei (groups of neurons of similar shape) deep within the forebrain Involved in the control of movement
    •  The thalamus The hypothalamus
    •  Has two lobes Most neural input to the cerebral cortex is received from the thalamus via projection axons
    • Thalamus lateral geniculate nucleus medial geniculate nucleusventrolateral nucleus
    • Thalamus Cerebral Cortex lateral primary geniculate visual cortex nucleus medial primary geniculate auditory nucleus cortex ventrolateral primary nucleus motor cortex
    •  The thalamus The hypothalamus
    •  Controls the automatic nervous system and the endocrine system Behaviors related to survival of the species, such as fighting, feeding and mating
    •  Inferior colliculi - part of the auditory system Superior colliculi - part of the visual system; involved in visual reflexes and reaction to moving objects
    •  Reticular formation - plays role in sleep and arousal, attention, muscle tonus, movement and various vital reflexes Periaqueductal gray matter - contains neural circuits that control sequences of movements such as fighting and mating.
    •  From the red nucleus emerges one of two major fiber systems that bring motor information from the cerebral cortex and cerebellum to the spinal cord The degeneration of neuron in the substantia nigra is responsible for Parkinson’s disease
    •  Cerebellum Pons
    •  The “little brain” Attached to the dorsal surface of the pons by bundles of axons Facilitates standing, walking or performance of coordinated movement, such as playing a musical instrument Receives and integrates visual, auditory, vestibular and somatosensory information about individual muscle movements and modifies the motor outflow by exerting a coordinating and smoothing effect on the movements.
    •  Contains portion of the reticular formation - important in sleep and arousal Also contains a large nucleus that relays information from the cerebral cortex to the cerebellum
    •  Medulla oblongata Contains part of the reticular formation As well as nuclei that controls vital function such as regulation of cardiovascular system, respiration, and skeletal muscle tonus
    •  A long, conical structure, approximately as thick as our little finger Distributes motor axons Collects somatosensory information Functions independently - reflexive control circuits
    •  Housed by the vertebral column 24 individual vertebrae cervical (neck) thoracic (chest) lumbar (lower back) sacral and coccygeal portions
    •  Spinal Nerves Cranial Nerves - serve sensory and motor functions of the head and the neck region
    •  Somatic nervous system - control movements of the muscles and to send sensory information from the sensory organs to the brain Autonomic nervous system - control of smooth muscles, cardiac muscles and glands
    •  Sympathetic nervous system – expenditure of energy from the reserves that are stored in the body Thoracolumbar system Parasympathetic nervous system - activities that are involved with the increase in the body’s supply of stored energy Craniosacral system
    •  Endocrine glands Processes that happen slowly, such as cell growth, regulation of mood Produces and secretes or give off chemicals - hormones Communicates messages, information and instructions to other group of cells
    •  Travel through the bloodstream to target cells (of body organs) Target cells have receptors that latch only onto specific hormones When hormone level reach a certain normal or necessary amount, further secretion is controlled by important body mechanisms - negative feedback system
    •  The primary link between the endocrine and nervous systems Controls the pituitary gland Releasing hormones - signal the pituitary gland to secrete stimulating hormones Somatostatin - causes the pituitary gland to stop the release of growth hormone
    •  “Master gland” because it makes hormones that control several other endocrine glands Can be influenced by factors such as emotions and seasonal changes Hypothalamus relays these information anterior lobe , posterior lobe
    •  Regulates the activity of the thyroid, adrenals, and reproductive glands Growth hormone Prolactin Thyrotropin Corticotrophin Follicle-stimulating hormone Leutinizing hormone Endorphins Gonadotropic hormones
    •  Antidiuretic hormone (vasopressin) Oxytocin
    •  Shaped like a bowtie or butterfly Thyroxine , triiodothyronine - regulate metabolism; body temperature and weight Iodine If iodine lacks in his/her diet, the thyroid cannot make the hormones – Goiter Calcitonin - regulation (reduction) of calcium level in the blood
    •  Secrete parathyroid hormone, or parathormone Parathormone - regulation (increase) of calcium level in the blood Hypoparathyroidism - insufficient secretion of parathyroid hormone leading to increased nerve excitability.
    •  Adrenal cortex Adrenal medulla
    •  corticosteroids such as cortisone - influences or regulates salt and water balance in the body; body’s response to stress, metabolism, the immune system and sexual development
    •  Steroid hormones in three classes: Mineralocorticoids maintain electrolyte balance Glucocorticoids produce a long-term, slow response to stress by raising blood glucose level through the breakdown of fats and proteins Sex hormones
    •  Catecholamines, such as epinephrine - increases blood pressure and heart rate when the body experiences stress
    •  Stimulated by the nerves from the eye Melatonin - a hormone that may help regulate the wake-sleep cycle (circadian rhythm) Secreted at night, when it is dark Depressing the activity of the gonads Affects thyroid and adrenal cortex functions Seasonal affective disorder
    •  Main source of sex hormones Testes located in the scrotum Ovaries, are located in the pelvis
    •  Androgens most important of which is testosterone regulate body changes associated with sexual development supports the production of sperm
    •  Produce eggs Estrogen - involved in the development of female sexual features Progesterone - causes the uterine lining to thicken in preparation for pregnancy Estrogen and progesterone - pregnancy and the regulation of the menstrual cycle
    •  Islets of Langerhans Glucagon - tells the liver to take carbohydrate out of storage to raise a low blood sugar level Insulin - tells the liver to take excess glucose out of circulation to lower a blood’s sugar level that’s too high Diabetes mellitus