Histology Embryology the muscularis externa*k Two layers of smooth muscle Myenteric nerve plexus responsible for peristalsis and segmentation Inner circular layer (circumferential) Myenteric(Auerbachs autonomic)nerve plexus Muscularis externa Longitudinal muscle Circular muscle Outer longitudinal layer --shortens gut Lumen Duct of gland outside alimentary can
the muscularis externa* Two layers of smooth muscle responsible for peristalsis and segmentation • Inner circular layer (circumferential) • Myenteric (Auerbach’s autonomic) nerve plexus • Outer longitudinal layer: ---shortens gut *
Histology Embryology Smooth muscle Smal Longitudinal laye intes of smooth muscle Circular layer Mucosa of smooth muscle Endomysium (b) Muscles are spindle-shaped cells oOne central nucleus o Grouped into sheets: often running perpendicular to each other ● Peristalsis No striations(no sarcomeres) o Contractions are slow sustained and resistant to fatique .Does not always require a nervous signal Nuclei of smooth muscle cells can be stimulated by stretching or hormones
Smooth muscle •Muscles are spindle-shaped cells •One central nucleus •Grouped into sheets: often running perpendicular to each other •Peristalsis •No striations (no sarcomeres) •Contractions are slow, sustained and resistant to fatigue •Does not always require a nervous signal: can be stimulated by stretching or hormones
Histology Embryology the outmost layer formed by CI with two types CT blending with surrounding structure +mestel (for example, peritoneum) Connective tissu Duct of gland
Adventitia *the outmost layer formed by CT with two types: fibrosa: CT blending with surrounding structure serosa: CT + mesothelium （for example, peritoneum）
Histology Embryology Enteric nervous system Mainly components 100 million neurons! (as many as the spinal cord) e unmyelinated nerve fibers controlling the muscles, glands and having sensory info o Muscularis external: Myenteric nerve plexus o Submucosa: Submucosal nerve plexus
Enteric nervous system: – Mainly components: • 100 million neurons! (as many as the spinal cord) • unmyelinated nerve fibers – controlling the muscles, glands and having sensory info • Muscularis external: Myenteric nerve plexus • Submucosa: Submucosal nerve plexus
Histology Embryology 米 Myenteric(Auerbach's)plexus regulate the movement of SM Inner circular 9 Nerve plexus Haino leuip4I6uol
Nerve plexus inner circular * Myenteric (Auerbach’s) plexus : regulate the movement of SM