Dr: Mohamed Khadar

Sensory Integration •      Survival depends upon sensation and perception •      Sensation is the awareness of changes in the internal and external environment •      Perception is the conscious interpretation of those stimuli Organization of the Somatosensory System •      Input comes from exteroceptors, proprioceptors, and interoceptors •      The three main levels of neural integration in the somatosensory system are: •    Receptor level – the sensor receptors •    Circuit level – ascending pathways •    Perceptual level – neuronal circuits in the cerebral cortex Processing at the Receptor Level •      Receptor potential – a graded potential from a stimulated sensory receptor •      Generator potential – depolarization of the afferent fiber caused by a receptor that is a separate cell (e.g., hair cell of the ear’s hearing receptor) •      If the receptor potential is above threshold, an

Joints (Articulations) •      Weakest parts of the skeleton •      Articulation – site where two or more bones meet •      Functions •    Give the skeleton mobility •    Hold the skeleton together Classification of Joints: Structural •      Structural classification focuses on the material binding bones together and whether or not a joint cavity is present •      The three structural classifications are: •    Fibrous •    Cartilaginous •    Synovial Classification of Joints: Functional •      Functional classification is based on the amount of movement allowed by the joint •      The three functional class of joints are: •    Synarthroses – immovable •    Amphiarthroses – slightly movable •    Diarthroses – freely movable Fibrous Structural Joints •      The bones are jointed by fibrous tissues •      There is no joint cavity •      M

Endocrine System: Overview •      Endocrine system –  the body’s second great controlling system which influences metabolic activities of cells by means of hormones •      Endocrine glands – pituitary, thyroid, parathyroid, adrenal, pineal, and thymus glands •      The pancreas and gonads produce both hormones and exocrine products •      The hypothalamus has both neural functions and releases hormones •      Other tissues and organs that produce hormones – adipose cells, pockets of cells in the walls of the small intestine, stomach, kidneys, and heart Hormones •      Hormones – chemical substances secreted by cells into the extracellular fluids •    Regulate the metabolic function of other cells •    Have lag times ranging from seconds to hours •    Tend to have prolonged effects •    Are classified as amino acid-based hormones, or steroids •      Eicosanoids – biologically active lipids with lo

Tissues/Histolgy Tissues •      Groups of cells similar in structure and function •      The four types of tissues •    Epithelial •    Connective •    Muscle •    Nerve Epithelial Tissue •      Cellularity – composed almost entirely of cells •      Special contacts – form continuous sheets held together by tight junctions and desmosomes •      Polarity – apical and basal surfaces •      Supported by connective tissue – reticular and basal laminae •      Avascular but innervated – contains no blood vessels but supplied by nerve fibers •      Regenerative – rapidly replaces lost cells by cell division Classification of Epithelia •      Simple or stratified •      Squamous, cuboidal, or columnar Epithelia: Simple Squamous •      Single layer of flattened cells with disc-shaped nuclei and sparse cytoplasm •      Functions  •    Diffusion