Ch. 4 Connective Tissue Muscle Tissue

1. Ch. 4 Connective TissueMuscle Tissue

2. Figure 4-18 Muscle Tissue Skeletal Muscle Tissue Cells are long, cylindrical, striated, and multinucleate. Nuclei LOCATIONS: Combinedwith connective tissuesand neural tissue inskeletal muscles FUNCTIONS: Moves orstabilizes the position ofthe skeleton; guardsentrances and exits tothe digestive,respiratory, and urinarytracts; generates heat;protects internal organs Musclefiber Striations LM  180 Skeletal muscle Cardiac Muscle Tissue Nucleus Cells are short, branched,and striated, usually with asingle nucleus; cells areinterconnected byintercalated discs. LM  180 Cardiacmusclecells LOCATION: Heart FUNCTIONS:Circulates blood;maintains blood(hydrostatic) pressure Intercalateddiscs Striations LM  450 Cardiac muscle Smooth Muscle Tissue Cells are short, spindle-shaped, andnonstriated, with a single, centralnucleus. LOCATIONS: Found inthe walls of blood vesselsand in digestive, respiratory,urinary, and reproductive organs Nucleus FUNCTIONS: Moves food,urine, and reproductive tractsecretions; controlsdiameter of respiratorypassageways; regulatesdiameter of blood vessels Smoothmusclecell LM  235 Smooth muscle

3. 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

4. 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)

5. Figure 4-18a Muscle Tissue Skeletal Muscle Tissue Cells are long, cylindrical, striated, and multinucleate. Nuclei LOCATIONS: Combinedwith connective tissuesand neural tissue inskeletal muscles FUNCTIONS: Moves orstabilizes the position ofthe skeleton; guardsentrances and exits tothe digestive,respiratory, and urinarytracts; generates heat;protects internal organs Musclefiber Striations LM  180 Skeletal muscle

6. 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

7. Figure 4-18b Muscle Tissue Cardiac Muscle Tissue Nucleus Cells are short, branched,and striated, usually with asingle nucleus; cells areinterconnected byintercalated discs. Cardiacmusclecells LOCATION: Heart FUNCTIONS:Circulates blood;maintains blood(hydrostatic) pressure Intercalateddiscs Striations LM  450 Cardiac muscle

8. 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

9. Figure 4-18c Muscle Tissue Smooth Muscle Tissue Cells are short, spindle-shaped, andnonstriated, with a single, centralnucleus. LOCATIONS: Found inthe walls of blood vesselsand in digestive, respiratory,urinary, and reproductive organs Nucleus FUNCTIONS: Moves food,urine, and reproductive tractsecretions; controlsdiameter of respiratorypassageways; regulatesdiameter of blood vessels Smoothmusclecell LM  235 Smooth muscle

10. Nervous Tissue

11. 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”

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

13. 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