Lab 4 Practical Histology PDF

Lab4 Practical histology Msc. Aiyat Hazem Muscle Tissue Special terms have been used for the various cytoplasmic organelles of the muscle fibers:  Plasma membrane—sarcolemma  Cytoplasm—sarcoplasm There are following three types of muscles...

Lab4 Practical histology Msc. Aiyat Hazem Muscle Tissue Special terms have been used for the various cytoplasmic organelles of the muscle fibers:  Plasma membrane—sarcolemma  Cytoplasm—sarcoplasm There are following three types of muscles: 1. Skeletal muscle 2. Cardiac muscle 3. Smooth muscle Skeletal Muscle Characterization 1. Skeletal muscle fibers are long 2. Cylindrical 3. Multinucleated cells, with peripheral nuclei. 4. Skeletal muscles attached to bones Figure: Longitudinal and transverse sections of skeletal (striated) muscles of the tongue Smooth Muscle 1. Smooth muscle fibers are appear smooth non- striated. 2. Contain a single central nucleus. 3. Smooth muscles are found in the linings of visceral hollow organs and blood vessels Lab4 Practical histology Msc. Aiyat Hazem Figure: Longitudinal and transverse sections of smooth muscle in the wall of the small intestine. Cardiac Muscle 1. Cardiac muscle fibers are also cylindrical 2. Cardiac muscle fibers exhibit only one or two central nuclei. 3. The terminal ends of adjacent cardiac muscle fibers show characteristic and dense-staining, end-to-end junctional complexes called intercalated disks. 4. They are primarily located in aorta and pulmonary trunk. Lab4 Practical histology Msc. Aiyat Hazem Figure: Longitudinal and transverse sections of cardiac muscle Nervous tissue The mammalian nervous system is divided into two major parts: 1- central nervous system (CNS) The CNS consists of the brain and spinal cord 2-peripheral nervous system (PNS).: The components of the PNS— the cranial and spinal nerves—are located outside the CNS. general structure of nervous tissue: The structural and functional cells of the nervous tissue are the neurons. Each neuron consists of 1-soma or cell body. 2- dendrites. 3-single axon. Lab4 Practical histology Msc. Aiyat Hazem Surrounding the neurons are the smaller and more numerous supportive cells collectively called neuroglia. These cells form the nonneural components of the CNS. Supporting Cells in the CNS: Neuroglia The four types of neuroglia cells are (astrocytes, oligodendrocytes, microglia, and ependymal cells). Types of Neurons in the CNS The three major types of neurons in the nervous system 1. Unipolar neurons:. Most neurons in the adult organism that exhibit only one process leaving the cell body were initially bipolar during embryonic development. The two neuronal processes fuse during later development and form one process. The unipolar neurons (formerly called (pseudounipolar neurons) are also sensory. Unipolar neurons are found in numerous sensory ganglia of cranial and spinal nerves. Lab4 Practical histology Msc. Aiyat Hazem 2. Bipolar neurons. These are not as common and are purely sensory neurons. In bipolar neurons, a single dendrite and a single axon are associated with the cell body. (retina of the eye). 3. Multipolar neurons. These are the most common type in the CNS and include all motor neurons and interneurons of the brain, cerebellum, and spinal cord. Projecting from the cell body of a multipolar neuron are numerous branched dendrites. On the opposite side of the multipolar neuron is a single axon. Bipolar neuron Multipolar neuron Pseudo-unipolar The Protective Layers of the Central Nervous System (CNS) 1- dura mater :The outermost meningeal layer, strong, and thick layer of dense connective tissue fibers. 2- arachnoid mater :Deep to the dura mater is a more delicate connective tissue, The dura mater and arachnoid mater surround the brain and spinal cord on their external surfaces. 3- pia mater :The innermost meningeal layer ,the delicate connective tissue. This layer contains numerous blood vessels and adheres directly to the surfaces of the brain and spinal cord. Lab4 Practical histology Msc. Aiyat Hazem Between the arachnoid mater and the pia mater is the subarachnoid space. Circulating in the subarachnoid space is the cerebrospinal fluid (CSF) that bathes and protects both the brain and spinal cord. Dura mater Arachnoid mater Pia mater Subarachnoid space Spinal cord (transverse section)