Ch. 4 Connective Tissue Muscle Tissue

Figure 4-18 Muscle Tissue Skeletal Muscle Tissue Cardiac Muscle Tissue Smooth Muscle Tissue Smooth muscle Cardiac muscle Skeletal muscle Cells are long, cylindrical, striated, and multinucleate. LOCATIONS: Combined with connective tissues and neural tissue in skeletal muscles FUNCTIONS: Moves or stabilizes the position of the skeleton; guards entrances and exits to the digestive, respiratory, and urinary tracts; generates heat; protects internal organs Cells are short, branched, and striated, usually with a single nucleus; cells are interconnected by intercalated discs. FUNCTIONS: Circulates blood; maintains blood (hydrostatic) pressure LOCATION: Heart Cells are short, spindle-shaped, and nonstriated, with a single, central nucleus. LOCATIONS: Found in the walls of blood vessels and in digestive, respiratory, urinary, and reproductive organs FUNCTIONS: Moves food, urine, and reproductive tract secretions; controls diameter of respiratory passageways; regulates diameter of blood vessels Nuclei Muscle fiber Striations LM  180 LM  450 LM  235 Nucleus Cardiac muscle cells Intercalated discs Striations Nucleus Smooth muscle cell

Three types of muscle Skeletal, smooth and cardiac muscle Epithelia – lined outside and inside of body and cavities Connective – supported and connected parts Major function of many organs and organ systems involves MOVEMENT; either of a substance (digestive system and circulatory system) or of the body (skelato-muscular) Muscle cells – distinct organelles and properties Muscle cells and muscle tissue are specialized to CONTRACT

Skeletal Muscle Very long, very slender muscle cells called muscle fibers Multinucleate Can divide Muscle usually grows because satellite stem cells called myosatellite cells divide Can repair after injury Fibers made of proteins called actin and myosin Contractile Appear banded or “striated” Voluntary Most predominant form of tissue in human body Held together by elastin and collagen and blended with tendons Which are attached to bones, contraction moves bone at joint ( think hinge)

Figure 4-18a Muscle Tissue Skeletal Muscle Tissue Skeletal muscle Cells are long, cylindrical, striated, and multinucleate. LOCATIONS: Combined with connective tissues and neural tissue in skeletal muscles FUNCTIONS: Moves or stabilizes the position of the skeleton; guards entrances and exits to the digestive, respiratory, and urinary tracts; generates heat; protects internal organs Nuclei Muscle fiber Striations LM  180

Cardiac Muscle Located only in the heart Cardiocytes Most with one nucleus Prominent striations Branching – highly interconnected; fan out of message to contract = heart beat Connections are called intercalated discs and contain desmosomes, proteoglycans and gap junctions = cells are locked tight together and ions responsible for beat can flow through Limited ability to repair damaged/dead cells “pace maker” cells vs nerve cells Striated INVOLUNTARY

Figure 4-18b Muscle Tissue Cardiac Muscle Tissue Cardiac muscle Cells are short, branched, and striated, usually with a single nucleus; cells are interconnected by intercalated discs. FUNCTIONS: Circulates blood; maintains blood (hydrostatic) pressure LOCATION: Heart LM  450 Nucleus Cardiac muscle cells Intercalated discs Striations

Smooth Muscle Located in walls of blood vessels and hollow organs like intestine and bladder Often in layers Smaller cells; tapered at each end with oval nucleus Because of nuclei, they can regenerate after injury Actin and myosin arranged differently – no striations Under nervous control, but not conscious control = 8 m of intestine and miles of blood vessels would be a lot to think about! Non-striated, involuntary

Figure 4-18c Muscle Tissue Smooth muscle Cells are short, spindle-shaped, and nonstriated, with a single, central nucleus. LOCATIONS: Found in the walls of blood vessels and in digestive, respiratory, urinary, and reproductive organs FUNCTIONS: Moves food, urine, and reproductive tract secretions; controls diameter of respiratory passageways; regulates diameter of blood vessels LM  235 Nucleus Smooth muscle cell Smooth Muscle Tissue

Nervous Tissue

Neural or Nervous Tissue Conducting electrical impulses 98% within brain and spinal cord (CNS) Neurons = nerve cells Many without nuclei Very limited ability to repair Neuroglia = supporting cells; connective tissue; “glue” Support Supply nutrients Some repair Electrical impulses are “transmembrane potentials”

Figure 4-19 Neural Tissue NEURONS NEUROGLIA (supporting cells) Maintain physical structure Repair tissue framework Perform phagocytosis Regulate the composition of the interstitial fluid surrounding neurons of tissues after injury Provide nutrients to neurons Axon Nucleolus Nucleus of neuron Dendrites (contacted by other neurons) Axon (conducts information to other cells) Cell body Dendrites Mitochondrion Nucleus Microfibrils and microtubules Nucleolus Cell body (contains nucleus and major organelles) A representative neuron (sizes and shapes vary widely) Contact with other cells Nuclei of neuroglia LM  600

Transmembrane Potential Cell membranes have an associated electrical potential This means that the ion concentrations of the cytoplasm and the extracellular fluid are slightly different and there is a charge difference from one side of the CM to the other side Long, thin wires = rapid conduction Measured in millivolts mV / microsecond Nerve impulses temporarily reverse this charge or polarity Na, K, Ca, Cl Must be restored before it can refire