lecture 3 Anatomy of Digestive System.pdf
Transcript
Instructor : Dr. Abdulhafeed S. Dalab PhD in Anatomy and Cell Biology Department of Veterinary Medicine Faculty of Agriculture and Veterinary Medicine June, 2021 Digestive System Functions Organs concerned with: 1. Reception (Prehension) of food with the lips and mouth. 2. Mechanical breaking do...
Instructor : Dr. Abdulhafeed S. Dalab PhD in Anatomy and Cell Biology Department of Veterinary Medicine Faculty of Agriculture and Veterinary Medicine June, 2021 Digestive System Functions Organs concerned with: 1. Reception (Prehension) of food with the lips and mouth. 2. Mechanical breaking down of the food by chewing (mastication). 3. Digestion of food stuff by enzymatic and chemical reactions. 4. Absorption of nutrients and water. 5. Elimination of wastes. 2 Digestive System Consists of : 1. Alimentary canal (Mouth to anus) a) b) c) d) e) 2. 3. 4. 5. 3/5/2024 Mouth and pharynx Esophagus and stomach Small intestine Large intestine Anal canal Accessory glands Salivary glands Liver pancreas 3 Mouth 3/5/2024 4 Mouth The main function of the oral cavity is the mastication of food. the mouth includes : Lips Oral cavity and its walls as well as the accessory structures Tongue Teeth Salivary glands 3/5/2024 5 Lips (oral fissure) Opining of the mouth used for Prehension of food Communication and suckling in newborn animals they contain tactile hairs in some species The form of the lips is determined by diet and feeding habits In horse: lips used in collecting food; for this they are sensitive and mobile In cat : teeth and tongue are more important for prehension, the lips are less mobile and much reduced in size In dog: it can be drawn back from teeth to signal of aggression, but are incapable of food intake, the upper lip has (philtrum) In ox and pig: the upper lip is modified to form extensive moist nasolabial plate (ox) and rostral disc (plate) in pig 3/5/2024 6 Dog 3/5/2024 Horse Sheep Cow 7 Lips (oral fissure) They are two Musculo-membranous structure bounding the oral fissure. the upper and lower lips are united at the angles of the mouth ( mouth commissures). Lips are attached to the incisive bone and the incisive part of the mandible. 3/5/2024 8 Oral Cavity The oral cavity is divided into : Vestibule (it is the portion of the oral cavity formed by the reflection of mucous membrane from the lips and cheeks in to the gums). Its subdivided into: Proper oral cavity It’s the space within the dental arcades 3/5/2024 Labial vestibule (space between teeth and lips) Buccal vestibule (space between teeth and cheeks) Bound by : Hard palate (dorsally) Tongue (ventrally) Teeth, dental arcades and gum (laterally and rostrally) Oropharynx and soft palate (caudally) 9 3/5/2024 10 The Mouth Species differences In horse and ruminant:- the mouth is relatively small, and their digestive tube is long. In carnivores:- the mouth opening is very large, and their digestive tube is short. 3/5/2024 11 Cheeks ( Buccae ) Its role is to return food that “escaped” into the vestibule, back into the central oral cavity. The are formed by : Buccinator muscle Salivary glands (buccal glands)- aggregated in carnivores to form zygomatic salivary gland Small papilla- significant in ruminant to provide protection against dryness of food ( large, caudally directed pointed papillae) 3/5/2024 12 Buccal papilla 3/5/2024 13 Dental pad a firm ridge replacing the incisors teeth and canine teeth in the upper jaw in the ruminants only. 3/5/2024 14 Palate The palate is a partly osseous, partly soft tissue that separates the digestive and respiratory passages of the head. The hard palate: Formed by the palatine processes of maxilla and incisive bones and horizontal plate of the palatine bone. The oral side of the hard palate is covered by a thick, cornified mucosa which crossed by a series of transvers ridges In ruminant these ridges carry papillae directed caudally to guide food backwards. A small median swelling, the incisive papilla is located just caudal to incisors (orifice of the incisive ducts of vomernasal organ- blind canal lined by olfactory mucosa). 3/5/2024 15 incisive papilla 3/5/2024 16 The hard palate The hard plate is divided into two symmetrical halves by shallow groove (median palatine raphe), while in the dog it is divided by median palatine crest (cleft palate). dog 3/5/2024 cow 17 The soft palate It is continues caudally from the hard palate to intrapharyngeal opening. It has 2 surfaces Ventral : covered by oral mucosa Dorsal : covered by respiratory mucosa the intermediate layer consists of: Closely packed salivary glands and muscles 3/5/2024 18 Tongue (lingua, glossa) composed primary of skeletal muscle occupies the greater part of the oral cavity and extends into the oropharynx. Responsible for lapping water, prehension of food, manipulating the food with mouth and swallowing. Possesses receptors for taste, temperature and pain In dog its used to enhance heat loss by panting. 3/5/2024 19 divided into apex, body, and root. Tongue 1- Apex: it’s the free rostral end of the tongue. 2- Body: its the middle of the tongue attaching to the mandible. the body is joined the oral floor by mucosal fold ( frenulum) in carnivores: the ventral part of the tongue contains a rodshaped fibrous body called (lyssa) extend from the tip of tongue to the root the dorsal aspect of the canine tongue is marked longitudinally by ( median groove) In cattle : the caudal part of the dorsal surface of tongue is raised to form a large prominence (torus linguae) that is defined by the transverse lingual fossa. In the horse : the tongue is strengthened by cartilage within the dorsal part of the tongue 3- Root: the caudal end of the tongue attaching to the hyoid bone. 20 Tongue 3/5/2024 21 Horse Species differences In dog: it is wide and flat with sharp borders. In horse: it is spatular with rounded borders. In ruminants: it is pointed with rounded borders. 3/5/2024 22 Tongue papillae The distribution, size, number and form are characteristic for each species. Based on their function they are grouped into : Mechanic papillae Cornified, aid in licking and protect the deeper structures from injury. Filiform papillae Conical papillae Marginal papillae Gustatory papillae covered in tasted buds 3/5/2024 Fungiform papillae Vallate papillae Foliate papillae 23 Tongue papillae 24 Mechanical papillae They are more numerous than gustatory papillae The filiform papillae The smallest and most numerous of all papillae The conical papillae Larger but less frequent, Rasp-like surface Scatterd widely over the dorsal surface of feline tongue At the base of the tongue in ox Marginal papillae Present in newborn carnivores and piglets and aids suckling 3/5/2024 25 The filiform papillae 3/5/2024 26 3/5/2024 27 The conical papillae 3/5/2024 Cat's tongue 28 Marginal papillae 3/5/2024 29 Gustatory papillae they contains taste buds, which are sensitive to taste There names indicate the shape few salivary glands are situated in close proximity to these papillae. These glands for removal of food particles from the papillae, making them ready for new food materials entering the mouth. 3/5/2024 30 Fungiform papillae They are mushroom-shaped structures with rounded surface. Contain taste buds on the dorsal surface of the tongue, especially at the borders Found in equine and bovine. have gustatory and mechanical functions. 3/5/2024 31 Tongue papillae 32 Fungiform papillae 3/5/2024 33 Vallate papillae Large papilla surrounded by a circular cleft and do not project above the surface of the tongue. Located on the dorsum, rostral to the root of the tongue. Numerous taste buds are found on the sides of the papilla. Numbers of these papillae varies with the species. 3/5/2024 34 Vallate papillae 3/5/2024 35 Foliate papillae Series of parallel leaves separated by furrow (crypts). Located on the lateral border of the tongue. They are absent in ruminants but well developed in the horse and dog. 3/5/2024 36 Tongue papillae 37 Lingual muscles Intrinsic muscles or lingual muscle proper: They form the bulk of the tongue and consist of: 1. 2. 3. Longitudinal bundles: they extend in both superficial and deep layers, from the apex to the root of the tongue. Transverse bundles: they extend from side to side. Perpendicular bundles: they have dorsoventral orientation. These bundles can alter the shape of the tongue during swallowing and chewing. 3/5/2024 38 Blood supply Paired lingual artery Sublingual artery Sublingual vein – can easily visible on ventral side of the tongue Used in venipuncture in clinic. 3/5/2024 39 Innervations of the tongue: The sense of taste to the rostral two thirds of the tongue is carried by the chorda tympanic. Note: Facial nerve (VII) gives off chorda tympanic. The sense of taste to the caudal third of the tongue is carried by the glossopharyngeal (IX) and vagus (X) nerves. The sense of pain, temperature and tactile is carried by the lingual nerve. Note: Trigeminal nerve gives off mandibular nerve, which gives off lingual nerve. The motor innervation to the intrinsic and extrinsic lingual muscles is carried by hypoglossal nerve (XII). 3/5/2024 40 3/5/2024 41 Salivary glands They are paired organ that secrete saliva via their ducts into oral cavity saliva is important for preparation of food for swallowing by lubrication and chemical digestion. Salivary glands classified by : Size Major or minor Duct length Short or long Secretion Serous or mucus or both 3/5/2024 42 Minor salivary glands Glands that present in the mucosa of the lips, cheeks, tongue, palate and sublingual floor These glands produce mucous secretion They are named based on location e.g. labial, buccal gland in ruminant and zygomatic gland in dog They have short ducts they are only locally important 3/5/2024 43 3/5/2024 44 Major salivary glands Located some distance from the oral cavity and empty their secretion via long duct. Most saliva is produced by the major salivary glands These glands produce a more watery (serous), some of them have serous-mucous(mixed) secretion. 3/5/2024 Amylase Water Mucin Salts Antibodies Glycoproteins 45 Major salivary glands Parotid S. gland : Unencapsulated, lobular gland Lies at the junction of head and neck, ventral to the auricular cartilage (ear) Well-developed in herbivores. Secretion : mixed (serous-mucous) In horse: it is overlays the lateral wall of the guttural pouch. It has several lobules by the action of the facial trabeculae 3/5/2024 46 Shape of major salivary glands parotid (PG), mandibular (MG) and sublingual glands (SG) In Angora goat MD MG PG PD SG 3/5/2024 47 Parotid S. gland PG 3/5/2024 48 Parotid S. gland duct The major collecting ducts pass within the trabeculae to eventually join, forming a single duct (rostrally). The parotid duct opens into the buccal vestibule (3-5 cheek tooth). In carnivores and small ruminants: the duct passes over the lateral surface of the masseter muscle. In horse, ox and pig: the duct passes medial to the angle of the jaw rostrally and winds around the ventral margin of the mandible to emerge at the rostral border of the masseter muscle. 3/5/2024 49 The parotid duct 3/5/2024 50 Mandibular S. gland Located close to the angle of the jaw and is partially covered by parotid gland. It is slightly bigger than parotid gland in dog and cat and larger in ruminants. Shape: round or oval Secretion : mixed (serous-mucous), but also alternate between the two. 3/5/2024 51 Mandibular s. gland duct Single large duct, passes ventral to the mucosa of the floor of the oral cavity/ medial to mandible. Open with the major sublingual duct near the sublingual caruncle / frenulum. Note: Sublingual caruncles : two mucosal folds that lie on either side of the frenulum of the tongue. 3/5/2024 Frenulum 52 Sublingual S. gland It consist of two gland on either side of the tongue. The major sublingual S. gland (monostomatic) absent in horse Situated more caudally but rostral to mandibular S. gland and drained by single duct Sharing a common opining with mandibular S. gland on the top of sublingual caruncle. The diffuse minor S. gland (polyostomatic) Located more rostally and opens through several smaller ducts in the lateral sublingual recesses Both sublingual glands produce a serous-mucoid secretion in which the mucous part dominates 3/5/2024 53 Sublingual S. gland 3/5/2024 54 Sublingual caruncle Sublingual caruncle (A), mandibular duct orifice (arrow) A 3/5/2024 55 Summary we identify Functions of digestive system Mouth Lips Oral cavity Tongue Salivary glands Oral cavity Vestibule Labial vestibule Buccal vestibule Proper oral cavity 3/5/2024 Dental pad the upper jaw in the ruminants only. Palate The hard palate transvers ridges incisive papilla median palatine raphe cleft palate (dog) The soft palate Ventral : covered by oral mucosa Dorsal : covered by respiratory mucosa 56 Summary Tongue papillae we identify Mechanic papillae Tongue function Tongue division :apex, body, and root Lyssa (dog) median groove (dog) torus linguae (cattle) the transverse lingual fossa (cattle) Gustatory papillae 3/5/2024 Filiform papillae Conical papillae Scatterd widely over the dorsal surface of feline tongue Marginal papillae Present in newborn carnivores and piglets covered in tasted buds Fungiform papillae mushroom-shaped, Contain taste buds on the dorsal surface have gustatory and mechanical functions Vallate papillae surrounded by a circular cleft , Numerous taste buds are found on the sides Foliate papillae parallel leaves , lateral border of the tongue, are absent in ruminants , developed in horse and dog. 57 we identify Summary Blood supply of tongue Paired lingual artery Sublingual artery Sublingual vein Nerve supply of tongue rostral two thirds chorda tympanic the caudal third glossopharyngeal (IX) and vagus (X) sense of pain, temperature and tactile lingual nerve intrinsic and extrinsic lingual muscles Salivary glands classified by : Size Major or minor Duct length Short or long Secretion Serous or mucus or both hypoglossal nerve (XII 3/5/2024 58 we identify Summary Minor salivary glands present in the mucosa of the lips, cheeks, tongue, palate and sublingual floor mucous secretion are named based on location e.g. labial, buccal gland in ruminant and zygomatic gland in dog They have short ducts Major salivary glands Most saliva is produced by the major salivary glands These glands produce a more watery (serous), some of them have serous-mucous(mixed) secretion. long duct 3/5/2024 59 we identify Summary Parotid S. gland lobular gland, several lobules by trabeculae ventral to the auricular cartilage (ear) mixed (serous-mucous) 3/5/2024 The major collecting ducts eventually join forming a single duct opens into the buccal vestibule In carnivores and small ruminants: the duct passes over the lateral surface of the masseter muscle. In horse, ox and pig: the duct passes medial to the angle of the jaw , emerge at the rostral border of the masseter muscle. 60 we identify Summary Mandibular S. gland Located close to the angle of Single large duct, passes ventral to the mucosa of the floor of the oral the jaw cavity covered by parotid gland. mixed (serous-mucous), but Open with the major sublingual duct near the sublingual caruncle / also alternate between the frenulum. two. 3/5/2024 61 we identify Summary Sublingual S. gland It consist of two gland on either side of the tongue. The major sublingual S. gland (monostomatic absent in horse The diffuse minor S. gland (polyostomatic) Both sublingual glands produce a serous-mucoid which the mucous part dominates 3/5/2024 62
