Lectures Flashcards
Name the regions of the abdomen.
From cranioventral clockwise : Xiphoid, left hypochondral, left flank, left inguinal, pubic, right inguinal, right flank, right hypochondral - and umbilical in the middle
What is the cranial region of the abdomen bounded by?
Xiphoid cartilage and the L and R hypochondral
What is the middle region of the abdomen bounded by?
Umbilical in middle, L and R flank either side
What is the caudal region of the abdomen bounded by?
Pubic area in the middle, L and R inguinal either side
What are the three lateral muscles of the abdominal wall? Which order are they in?
From superficial to deep: External abdominal oblique (travels cranial to caudal), Internal abdominal oblique ( travels caudal to cranial), Transverse abdominus (travels dorsoventrally)
What is the term for a midline vental surgical incision?
Midline coeliotomy
Which muscle forms the ventral boundary of the abdominal cavity
Left and right rectus abdominus
The labial surface of the tooth faces the
Lips
The buccal surface of the tooth faces the
Cheeks
The lingual surface of the tooth faces the
Tongue
The vestibular surface of the tooth faces the
Lips or cheeks depending on its location
Interproximal or interdental surfaces face
Teeth in the same arcade
The mesial surface of a tooth faces the adjacent tooth that is
Closest to midline
The distal surface of a tooth faces the adjacent tooth that is
Furthest from midline
The crown is the
Part of the tooth that is covered in enamel
What is the difference between the clinical crown and the reserve crown?
In hyposodont teeth only. The reserve crown is the portion of the crown that remains beneath the gumline.
What is the name of the tooth section that has no enamel coating?
The root
Which substance forms the outermost layer of hypsodont teeth?
Cementum
Which substance occurs in both the root and crown of brachydont teeth?
Dentine
Eruption commences before root formation in which tooth type?
Hypsodont
Which cells synthesise enamel?
Ameloblasts
What features of enamel make it an effective tooth covering?
- strong and smooth to protect tooth from mechanical wear and infection
- forms sharp ridges to assist with mastication
Which cells synthesise dentine?
Odontoblasts
What is the location and function of primary dentine?
It is the second layer after the enamel. It functions to protect the pulp cavity if the enamel layer becomes compromised
What is the location and function of secondary dentine?
Laid down deep to primary dentine in response to mechanical stress on the tooth. Functions as a second line of defence for the pulp cavity. Takes up plant matter stain.
What is the location and function of tertiary dentine?
Laid down deep to secondary dentine in response to tooth injury or damage. Last line of defence for the pulp cavity
Three functions of cementum?
- Surrounds and protects the pulp cavity in the root
- Anchors the periodontal ligament
- Contributes to bulk of crown in hypsodont teeth
Three functions of the alveolus?
- Attaches the periodontal ligament to the jaw
- Surrounds and supports the tooth and its root
- Cancellous bone absorbs some shock
Name the four fibre types of periodontal ligament.
Crest, horizontal, oblique, apical
Which part of the primordial tooth become ameloblasts?
Inner enamel epithelium
Which part of the primordial tooth becomes the pulp cavity?
The dental papilla
Which part of the primordial tooth becomes the odontoblasts?
The uppermost layer of the dental papilla
Which primordial structure becomes the cementoblasts?
The inner layer of the dental sac
Which primordial structure becomes the periodontal ligament?
The middle layer of the dental sac
Which primordial structure becomes the osteoblasts?
The outer layer of the dental sac
The palatine surfaces of the tooth faces the
Hard palate - upper arcade teeth only
True or false - a 5 year old horse is likely to have roots present for his hypsodont teeth.
False. Horses may not develop tooth roots until 17 years of age due to continuous tooth growth.
The greater the ______ content, the stronger the tooth material is (enamel vs. cementum vs. dentine)
Hydroxyapetite (a calcium phosphate complex)
Which tooth layer takes up the plant material stain?
Secondary dentine and cementum that occurs above the gumline in herbivores
Why is floating horse teeth possible?
Because the dentine at the clinical crown surface is not sensitive, owing to calcification of the extending odontoblast processes at this level.
Periodontal ligaments can regenerate. Which cells produce the periodontal ligament and what is it made of?
Fibroblasts - formed from collagen bundles called Sharpey’s fibres.
What does ‘diphyodont’ mean?
Having of two sets of dentition (one deciduous, one permanent). Animals may also be monophyodont or polyphyodont e.g elephants
In tooth development, what structure does the primordium form?
The permanent tooth
List the layers, from superficial to deep, of a late stage developing tooth
Stellate reticulum, ameloblasts, enamel, dentine, pre-dentine, odontoblasts, dental pulp
What defines tooth ‘growth’ phase?
The laying down of enamel. Once this has ceased, formation of the root begins.
What is the dental formula for a dog?
3142/3143 x 2
Which teeth are known as carnassials in dogs?
Upper PM4 and Lower M1
What is the feline dental formula?
3131/3121 x 2
What is the dental formula for a pig?
3143/3143 x 2
What sort of teeth are tusks in pigs (brachy or hypso)?
Hypsodont, project laterally, used for fighting
What sort of teeth are the lower incisors in pigs? What are they used for?
Brachydont - project rostrally, used for digging
What is the equine dental formula?
31(0)3(4)3 / 31(0)3(4)3 x 2
- may be no wolf tooth or canine present
What sort of tooth is the wolf tooth (brachy or hypso)?
Brachydont
On which surfaces would you be concerned about sharp enamel ridges developing in a horse?
Buccal area of the maxillary arcade and lingual area of the mandibular cheek teeth
What is the dental formula for a cow /sheep?
0033/3133 x 2
What is the nature of ruminant incisors (hypso or brachy)?
Brachydont
True or false: The more level a cow’s incisors are, the younger she is.
False. The incisors start off oblique and wear to level with age.
In which species does the fighting tooth occur? Which tooth is it? What sort of tooth (brachy/hypso)?
Alpacas, upper incisor 3, hypsodont.
What is the lapine dental formula?
2033/1023 x 2
What creates the chisel shape of the peg teeth in rabbits?
Rostral surface has enamel coating, but caudal has dentine, allowing it to wear
What does it mean to have hypselodont teeth?
They never stop growing throughout life, and never form a root.
How is it possible to trim rabbit incisors without anaesthesia? Is it recommended?
Because the pulp cavity only projects 3mm above the gumline, so much of the incisors are not innervated. It is not recommended to do this because the cause of the protruding incisors may lie deeper in the oral cavity, which is difficult to examine without GA or sedation
True or false : rats have hypselodont incisors and brachydont cheek teeth.
True
What are the rough eruption times for dog teeth?
Deciduous: 4 - 6 weeks
Permanent: 4 - 6 months
What are the rough eruption times for cat teeth?
Deciduous: 2 - 6 weeks
Permanent: 4 - 7 months
What are the eruption dates for the deciduous incisors of a horse?
I1 = 0 - 1 weeks I2 = 4 - 6 weeks I3 = 6 - 9 months
What are the eruption dates for the permanent incisors of a horse?
I1 = 2.5 years I2 = 3.5 years I3 = 4.5 years
In horse teeth, the hook of the upper corner incisor tends to appear around __ years of age?
10 years approx
What does ‘heterodonty’ mean?
The differing in shape and function of teeth within a species’ mouth to allow particular tasks to be performed.
True or false: In most cases, premolars have a deciduous precursor whilst molars do not.
True. The exceptions are PM1 in carnivores and horses.
Describe the morphology of carnassial teeth.
Rostrally sharp for cutting, caudally flat and blunt for crushing.
True or false: the molars of dogs and cats are adapted to grind bones.
False. Carnivores cannot ‘grind’ at all, only crush (not cats), cut and tear
When the cup has almost completely worn away, the remaining dark speck is known as ___ and it is composed of ____
The mark, cementum
The star appears on the labial side of the occlusal incisor surface. It represents _____ covered by _____?
the pulp cavity covered by dentine
The cup is also known as the __?
Infundibulum.
Wolf teeth are slightly more likely to occur in which arcade?
Upper.
Describe the dental pad.
Thick, keratinised piece of tissue in place of upper incisors that binds to bone allowing prehension of large mouthfuls
Describe the incisors of a 4 year old ruminant.
All four permanent teeth have erupted. Minimal wear.
Describe the incisors of a 7 year old ruminant.
Both the first and second incisors have levelled and the neck has emerged from the gums.
By what times are the permanent incisors of a horse in wear? (wear takes 6 months from eruption)
I1 = 3 years I2 = 4 years I3 = 5 years
What is the white spot sometimes seen in the centre of the star in the horse?
Tertiary dentine.
What are the rough eruption times for the central, middle, lateral and full mouth incisors in cattle?
Centrals = 2 years
Middles = 2.5 years
Laterals = 3 years
Full mouth = 4 years
Sheep are the same except may be two-tooth by 1.5 years
Which species have keratinised epithelia lining their lips?
Horses and ruminants
Which species do not have keratinised epithelia lining their lips?
Pigs and carnivores
What is the caudal barrier of the oral cavity?
The palatoglossal arch.
Which layer of the oral cavity contains the salivary glands?
The submucosa.
Describe the location and function of orbicularis oris.
Lies within the lips. Encircles the oral cavity opening and acts to close the lips.
Describe the location and function of levitator nasolabialis. Which cranial nerve innervates it?
Inserts into and raises the nose and upper lip. CN Vii (facial nerve).
Describe the function of levator labii superioris. Which cranial nerve innervates it?
Lifts the upper lip. Occurs deep to levitator nasolabialis. CN Vii (facial nerve)
What is the function of buccal papillae? Name one species in which they are present.
Direct food from the oral cavity toward the pharynx e.g camelids, ruminants.
Describe the location and function of the buccinator muscle. Which cranial nerve innervates it?
Occurs caudal to the lips in the cheeks. Contracts to form muscular tunic that returns food from the vestibule to the oral cavity proper. CN Vii (facial nerve)
Name one species specific adaptation of the palate.
The dental pad.
True or false - the palate contains salivary palatine glands.
True. The only domestic species without palatine glands is the pig.
True or false - the soft palate participates in deglutition.
True. It contains three paired muscles which shorten, tense and raise it.
True or false - the hyoid apparatus lies within the maxilla.
False. The hyoid apparatus lies within the mandible.
True or false - the tongue root attaches to the hyoid apparatus.
True (the basihyoid, specifically)
Which structure of the dog oral cavity is particularly involved in thermoregulation?
The frenulum - highly vascular, passing blood through the frenulum that is exposed plus panting will cause the blood to cool down.
Where specifically in the tongue do the gustatory glands occur?
In the sulci bordering the vallate papillae.
Name the four mechanical tongue papillae types.
- Conical (most species, though location varies slightly)
- Lentiform/lenticular (ox, torus linguae)
- Marginal (newborn dog and pig, rostral tongue)
- Filiform (all species, largest in cats, smallest in horses, assist with food grip and grooming)
Name the three gustatory tongue papillae types.
- Fungiform
- Foliate (form parallel folds, absent in cats and ruminants)
- Vallate (most species, location demarcates junction between body and root of tongue)
The lingual fossa occurs rostral or caudal to the torus in ruminants?
Rostral.
Name the five extrinsic muscles of the tongue.
Genioglossus Hyoglossus Mylohyoideus Geniohyoideus Styloglossus SHMGG
Describe the orientation and action of mylohyoideus.
Runs transversely, ventral to the tongue from the medial L mandible to the medial R mandible. Acts to lift the tongue dorsally to press against the palate
Describe the orientation and action of geniohyoideus.
- genio = chin
Paired, strap-like muscles running cranio-caudal from the basihyoid to the chin. Draws the tongue toward the basihyoid (caudally)
Describe the orientation and action of styloglossus.
Runs from the stylohyoid bone to the tongue, acts to draw the tongue caudally. Has three heads inserting onto the tongue.
Describe the orientation and action of hyoglossus.
Runs from the tongue root to the basihyoid, acts to retract and depress the tongue.
Describe the orientation and action of genioglossus.
- genio = chin
- glossus = tongue
Occurs within the frenulum - runs from the medial mandible to the tongue. Acts to depress and protrude the tongue
True or false - digastricus acts to open the jaw and runs from the paracondylar process of the occiput to the ventrolateral mandible.
False - digastricus inserts onto the ventromedial mandible.
Which cranial nerve innervates the extrinsic muscles of the tongue?
The hypoglossal nerve.
Sensory innervation to the tongue is provided by how many cranial nerves?
Two - CN V to the rostral two thirds, CN IX to the caudal third.
True or false - the facial nerve participates in detection of taste at the tongue.
True.
The muscles that close the mouth are innervated by which cranial nerve?
Trigeminal (CN V)
Name the three muscles associated with closing the jaws.
- Temporalis
- Masseter
- the Pterygoids
Describe the orientation and action of temporalis.
Originates on extensive area of lateral cranium and inserts at the coronoid process of the mandible. Contracts to pull mandible upward. Larger in carnivores.
Describe the orientation and action of masseter.
Originates at the maxillary skull and zygomatic arch, inserts at the caudal mandible over a wide area. Acts on the mandible to raise it, move it laterally and protrude it. Larger in herbivores.
Describe the orientation and action of the pterygoid muscles.
Paired - lateral and medial. Originate at the pterygopalatine region of the skull and insert at the medial mandible. Work with masseter to move mandible laterally (chewing). Also close and protrude lower jaw.
Which two bones articulate to form the temperomandibular joint?
The zygomatic processes of the temporal bone and the condyloid processes of the mandible.
True or false: the flatter articular surfaces at the TMJ in herbivores is an evolutionary adaptation to the herbivorous diet.
True. The flatness allows greater range of lateral movement at the joint, facilitating grinding of the jaw. Carnivore TMJs operate in a hinge-like fashion as they are constricted by bony processes.
True or false - herbivores tend to have a larger temporalis muscle (relative to their size) than carnivores.
False. Temporalis’ main function is to close the jaws, which is more important in predatory animals. Herbivores have larger digastricus, pterygoids and masseter for grinding food.
List the cavities from cranial to caudal that occur between the nasal cavity and the trachea
Nasal cavity, nasopharynx, intrapharyngeal osteum, larynx, trachea
List the cavities from cranial to caudal that occur between the oral cavity and the oesophagus.
Oral cavity, oropharynx, intrapharyngeal osteum, laryngopharynx, oesophagus.
Which structure is the oropharynx bounded by caudally?
Soft palate
Which structure is the nasopharynx bounded by ventrally?
Soft palate.
Name the three categories of intra-pharyngeal muscles.
- Dilating
- Constricting
- Shortening
Give three risk factors for periodontal disease development
Any of:
- plaque retentive diet
- concurrent disease such as diabetes, renal disease
- retained deciduous teeth or other teeth crowding
- exposed dentine
- mouth breathing
- xerostermia (oral cavity dryness)
What are the two minimum criteria for PD?
- Presence of a PD pocket colinized by bacteria
2. Active resorption of alveolar bone in presence of acute inflammation (recall that gum recession = bone resorption)
Name three defences of the oral cavity.
Any of:
- normal oral flora
- integrity of oral mucosa
- intra-oral lymphoid aggregations
- salivary contents (peroxidase, lactoferrin, lysozyme, IgA, IgM)
- mechanical disturbance of calculus through mastication
- enamel bulge of tooth
- smoothness of enamel
An animal laying on its right is in ______ recumbency?
Right lateral recumbency.
A radiograph taken of an animal laying on its back is known as a _____ projection?
Ventrodorsal projection - “VD”
Fluid is ____ on xray and ___ on ultrasound. Which is the better medium for observing fluid compared to soft tissue?
Fluid is grey on xray and black on ultrasound. Ultrasound allows distinction of fluid and soft tissue.
What angle should the normal stomach sit at in xray?
Angle of the ribs, roughly.
Why should animals be fasted prior to ultrasound?
Because shadows of ingesta can interfere with the findings.
Define calculus
Mineralised plaque present on both the crown and root of the tooth. The minerals come from the animal’s own saliva.
Define tartar.
Mineralised plaque present on the crown only.
Describe feline odontoclastic resorptive lesions (FORL)
Progressive resorption of the tooth beginning at the cemento-enamel junction mediated by odontoclasts. May occur with or without PD. Clinical signs include anorexia, lethargy, depression, halitosis, dysphagia, may have poor coat.
Give two hypothesised causes for FORL.
- Feline calicivirus infection
2. Chronic regurgitation
The maximum depth for the gingival sulci in health is:
Cats ___ mm
Dogs ___ mm
Cats = up to 1 mm Dogs = up to 3mm
Why is a retained deciduous tooth a risk to the animal’s dental health?
Because it shares a gingival cuff with its permanent counterpart, widening the possible entry route for bacteria into the tooth sulcus.
Give three possible causes of xerostermia (clinically significant reduction in saliva production)
- Malocclusion
- Dehydration
- Chronic renal disease
Also
- diabetes
- hypertension
- autoimmune disease
Crevicular fluid formation is proportionate to ____?
Crevicular fluid formation is proportionate to accumulation of plaque on the tooth.
Give two contents of crevicular fluid.
- IgA, IgM, IgG
- Macrophages
also
- lymphocytes
True or false: crevicular fluid may contribute to pathological inflammation associated with PD?
True. Crevicular fluid plays a defense role before PD is established, but may perpetuate inflammatory damage once PD has begun.
Why does plaque formation progress more rapidly during sleep?
Relative anaerobic conditions inside the oral cavity during sleep assist in growth of pathological gram negative bacterial species associated with PD
True or false - caries have been reported in all domestic species.
False - cats do not have flat occlusal surfaces and so caries are extremely rare/not seen.
Dentine is continually produced over time to protect the pulp cavity. The resulting effect on the pulp cavity is what?
Narrowing of the pulp cavity.
Name the four tissue types involved in periodontitis.
Gingiva, periodontal ligament, cementum and alveolar bone.
True or false - the pellicle normally contains bacteria.
False. However, bacteria may use it as an attachment site in the early stages of periodontitis.
Which important substance in the aetiology of PD can be described as a biofilm? Will antibiotics have much of an effect?
Plaque; no.
What is the time frame for gram negative bacterial species to dominate plaque?
10-14 days minimum
What is the hallmark of periodontal disease as seen on radiograph?
Attachment loss of the tooth from the alveolar bone.
On which aspect of the tooth are FORL lesions more common?
Buccal
The parotid gland is larger in ___vores?
Herbivores
The parotid gland is located ___ and its duct opens ___. Its duct follows a more direct route in ___vores.
Superficially, ventral to the ear, the duct opens near upper PM4, more direct route in carnivores.
True or false - the mandibular gland is superficial to the parotid gland.
False. The mandibular gland is deep to the parotid in all species. It lies at the angle of the jaw
Describe the duct trajectory of the mandibular gland.
A single duct travels rostrally along the floor of the oral cavity to open at the sublingual caruncle.
The sublingual gland runs along the oral cavity floor. It usually has both ___stomatic and ____stomatic parts. This relates to the ______.
Monostomatic and polystomatic parts. This relates to the number of ducts that drain the glandular tissue into the oral cavity.
The zygomatic gland is found in ___ only.
Carnivores only. Occurs medial to the zygomatic arch.
List the components of a salivary gland from acinus to oral cavity in order of salivary travel.
Acinus > intercalated duct > striated duct > interlobular duct > primary duct > oral cavity
In all species except the dog, the parotid gland produces purely ____ secretions?
Serous
Give two mixed mucoserous glands of the oral cavity in species other than the dog.
Mandibular
Sublingual
Which salivary duct has low cuboidal epithelium?
Intercalated duct
What sort of epithelium does a salivary striated duct have, and how do you tell them apart from intercalated ducts?
Columnar - there will be more apparent cytoplasm in each cell, the lumen will be larger and there may be basal striations present due to mitochondria localisation.
What kind of epithelium does a salivary interlobular duct have?
May be simple or stratified columnar
Two cranial nerves involved in salivary secretion are?
- Facial nerve CN VII
2. Glossopharyngeal nerve CN IX
During deglutition, what reflexes are initiated by contact of the bolus with the pharyngeal mucosa?
- Soft palate is raised to occlude the nasopharynx
- Glottis is closed over laryngopharynx
- Hyoid apparatus drawn rostrall and the pharynx is shortened, allowing the pharynx to move rostrally and engulf the bolus
What are the three segments of the oesophagus?
Cervical, thoracic, abdominal.
What are the boundaries of the cervical oesophagus?
Cranially the pharynx, caudally the thoracic inlet.
What are the boundaries of the thoracic oesophagus?
From the thoracic inlet to the oesophageal hiatus of diaphragm
The oesophagus travels _____ to the bifurcation of the trachea.
Dorsal.
True or false - the mucosa of the oesophagus exhibits prominent longitudinal folds.
True - these permit great dilation of the lumen.
Oesophageal epithelium is keratinised in which species?
Usually - pigs, horses and ruminants. Not carnivores
Does the oesophagus have glands? If so, what do they secrete?
Yes - occur in the submucosa. In most species they are concentrated at the cranial end. Secrete mucous.
True or false - oesophagi of various species lack a muscularis mucosae at the cranial end
True!
Which species have skeletal muscle composing the majority of their oesophagus’ muscularis externa? Which species have a mix of skeletal and smooth?
Skeletal: ruminant and dog (smooth muscle for area immediately cranial to the stomach in dogs)
Mix: cat, pig, horse.
Name three arteries supplying blood to the oesophagus
- Common carotid artery
- Broncho-oesophageal artery
- Left gastric artery
What are the high-risk sites for oesophageal obstruction?
- cranial and caudal openings
- thoracic inlet
- as it passes over the base of the heart
- immediately anterior to the diaphragmatic hiatus
When does the oesophagus have adventitia covering it vs. serosa?
Adventitia = when lies outside the thorax or abdomen Serosa = when lies inside thorax or abdomen
Give two major differences in the avian oesophagus relative to other domestic species.
- Presence of the crop in birds, cranial to the thoracic inlet
- The oesophagus passes on the right side of the cervical neck as opposed to the left side in mammals
The reticulum lies ______ to the rumen.
Cranial, to the left
The reticulum lies ____ to the xiphoid process.
Dorsal.
The diaphragmatic surface of the reticulum is convex or concave?
Convex.
The three openings of the reticulum are:
- The cardia
- The rumenoreticular orifice
- The reticulo-omasal orifice
Describe the macroscopic appearance of the reticulum mucosa.
The mucosa is arranged in protruding ridges forming a honeycomb pattern. Within each cell of the honeycomb, there are secondary mucosal ridges which are covered in low papillae. The papillae are also present on the floors of the cells.
What are three functions of the reticulum.
- Sieve coarse material from the ingesta so that it may be returned to the rumen
- Absorption of fatty acids, water and salts
- Passage of fine material to the omasum
Presence of which substances in the oral cavity may activate the reticulo-abomasal groove? What is the clinical significance of this?
Electrolyte salts, calcium, magnesium. We may add these substances to medications or feed we wish to bypass bacterial fermentation in the rumen.
Describe the microscopic appearance of the reticulum mucosa
Keratinised stratified squamous epithelium thrown into primary and secondary folds covered in small papillae. The folds contain a small core of smooth muscle (muscularis mucosa) giving the honeycomb structure a small amount of contractility. The papillae do not contain smooth muscle. The muscularis externa is thick, arranged in two directions and does not extend into the folds. The folds are 100% lamina propria.
Which part of the rumen may be palpated per rectum in a cow?
The dorsal sac
Over which part of the rumen does the paralumbar fossa occur? What is the clinical significance of this location?
The dorsal sac. Closest to body surface so best for auscultating the rumen and also for decompression access in case of bloat.
What structure occurs between the body wall and left ventral sac of the rumen?
The superficial layer of the greater omentum. It originates at the left longitudinal groove.
The dorsal and ventral left and right coronary grooves demarcate which structures from the majority of the rumen?
The caudo-dorsal and caudo-ventral blind sacs.
The left longitudinal groove separates which two sacs of the rumen?
The dorsal sac and the ventral sac
The cranial groove only occurs on the ____ side of the rumen and it separates the ___ sac from the ___ sac
The cranial groove only occurs on the left side of the rumen and it separates the ventral sac from the cranial sac.
The insula ruminus occurs only on the ___ side of the rumen and is demarcated by the ___ groove and the ___ groove.
The insula ruminus occurs only on the right side of the rumen and is demarcated by the right accessory groove and right longitudinal groove.
Viewing the rumen from the outside, what groove occurs between the caudodorsal and caudoventral blind sacs?
The caudal groove.
What structure envelops the intestinal mass in the ruminant? What is the name of the space in which they sit?
The greater omentum. The intestines sit within the supra-omental recess.
Where does the deep sheet of the greater omentum originate in the ruminant?
The right longitudinal groove.
The _____ pillar demarcates the cranial sac from the dorsal sac. It extends caudolaterally as the longitudinal pillars.
The CRANIAL pillar demarcates the cranial sac from the dorsal sac. It extends caudolaterally as the longitudinal pillars.
The left and right dorsal and ventral coronary pillars (four structures) correspond to what structures on the surface of the rumen?
The left and right dorsal and ventral coronary grooves.
WITHIN the rumen, what structure separates the caudo-dorsal and caud-ventral blind sacs?
The caudal pillar.
True or false - rumenal papillae contain smooth muscle.
False
True or false - the epithelium of the rumen is keratinised.
True - the rumen has stratified squamous epithelium.
True or false - the mucosa and submucosa of the rumenal epithelium are easily distinguished.
False. They are both composed of disorganised connective tissue with no intervening muscularis mucosa.
The parietal layer of the rumenal wall is adventitia or serosa?
Serosa.
Other than the lesser omentum, what major structure occurs dorsolaterally of the omasum, partially between it and the body wall?
The liver.
The contraction sequence for eructation begins with contraction of the the ____ and finishes with contraction of the ___.
The contraction sequence for eructation begins with contraction of the the caudoventral blind sac and finishes with contraction of the main ventral rumen.
Describe the macroscopic structure of the omasal mucosa.
The mucosa is thrown into parallel folds of five different sizes. They arise from the greater curvature and project toward the lesser curvature (and the omasal canal). The three most prominent fold sizes have contractile ability. The laminae are covered in tiny papillae giving a bumpy appearance.
Describe the microscopic structure of the omasal mucosa.
The omasum has stratified squamous epithelium. Small papillae project from the lamina propria - they contain no muscle. The three longest mucosal folds (primary, secondary and tertiary) contain both muscularis mucosa plus a core of muscularis externa. The intervening submucosa is very small. The smallest laminae (4 and 5) have muscularis mucosa only. The parietal layer of the omasum is a serosa.
Describe two internal structural features of the abomasum.
- The spiral folds arise around the omaso-abomasal orifice and continue toward the pyloric region, where they peter out.
- The torus pyloricus is a large swelling of mucosa projecting from lesser curvature to narrow the pyloric passage.
True or false: the abomasum contains a non-glandular region.
False. The regions of the abomasum are the cardiac, fundic and pyloric regions. There are glands present in each of these.
What are the three segments of the groove that conveys ingesta directly to the abomasum without entering the rumen?
- The reticular groove - from the cardia to the reticulo-omasal orifice
- The omasal groove - from the reticulo-omasal orifice to the omaso-abomasal orifice
- The abomasal groove - the area of the abomasum without gastric folds.
The majority of blood supplied to the compound stomach is via the:
Celiac artery and its various branches.
Smaller ruminants have a _____ reticulum, ____ ventral rumen sac and ___ omasum relative to the cow.
Smaller ruminants have a larger reticulum, large ventral rumen sac and smaller omasum relative to the cow.
Which section of the rumen protrudes more in smaller ruminants relative to the cow?
The caudoventral blind sac - protrudes more caudally than caudo-dorsal.
From which side is a C section typically performed in cattle? Why?
From the left
- don’t have to disrupt the lesser omentum and risk small intestinal herniation
The lesser curvature of the canine stomach is connected with which organ by which structure?
The lesser curvature is connected with the liver and the duodenum by the lesser omentum. Called the hepatogastric and hepatoduodenal ligaments respectively.
The greater curvature of the canine stomach is attached to which two important structures? What form this attachment?
Attached to the spleen and the greater omentum. A section of the greater omentum forms the gastrosplenic ligament.
The greater omentum attaches to the stomach and protectively encapsulates the intestinal mass. Give one other function of the greater omentum.
- Storage of fat
Four major branches of the celiac artery supply blood to the stomach and related viscera. Name them and the organs which they supply.
- Hepatic artery - liver, pylorus and duodenum
- Splenic artery - spleen, greater curvature of stomach
- Left gastric artery - lesser curvature of stomach
- Gastroduodenal artery - stomach and duodenum
If performing surgery on the stomach, where is the best location to make the incision?
If possible, through the wall between the two curvatures, as this is the least vascular area of the stomach.
Other than the ruminant, which species has the largest non-glandular region?
The horse - saccus caecus demarcated by the margo plicatus.
What is secreted by the cardiac region of the stomach?
Mucous and HCO3-
True or false - muscularis externa contributes to the rugae of the stomach.
False.
True or false - gastric glands lie in the submucosa.
False. They occur in the mucosa for all regions of the stomach.
Which layer of the muscularis mucosa contributes to the cardiac and pyloric sphincters?
The middle (circular) layer
Which region of the glandular stomach has the deepest pits?
The pyloric region.
Which reason of the glandular stomach has the deepest glands?
The fundic region.
The anatomic FUNDUS of the pig stomach has which sort/s of glandular epithelium?
Cardiac.
The anatomic BODY of the pig stomach has which sort/s of glandular epithelium?
Cardiac and fundic.
Which two domestic species feature a notable torus pyloricus in the glandular foregut?
Ruminants and the pig.
What is the clinical significance of the pars oesophagea in the pig?
It is prone to ulceration, particularly in intensively farmed individuals.
Which species exhibits a diverticulum in the cardiac region of the forestomach?
The pig.
The full stomach of the horse expands in which direction? Can it be palpated?
Dorsally; no.
Chief cells of the gastric glands produce ____. They have _____ basal cytoplasm due to lots of _____ within the cell.
Chief cells of the gastric glands produce pepsinogen. They have basophilic basal cytoplasm due to lots of RER within the cell.
True or false - Parietal cells are only present in the base of the gastric gland.
False - they are present along its length (neck, body, base)
Name three endocrine cells of the gastric mucosa and their products.
- G cells - gastrin
- D cells - somatostatin
- ECL cells - histamine
Describe one structural aspect of the canine stomach that assists with vomiting and suggest how it may have been advantageous for primitive dogs.
The cardia is wide, and the oesophagus enters the stomach at almost 90 degrees. This allows easy passage of ingesta back up the oesophagus (i.e vomiting). Dogs being scavengers, this was useful for eliminating toxins they might have consumed.
The anatomic BODY of the equine stomach contains which kind of gastric glandular epithelium?
Fundic.
The anatomic FUNDUS of the equine stomach contains which kind of gastric epithelium?
Non-glandular.
The fundus of the equine stomach expands in which direction (ventrally, dorsally, cranially, caudally)?
Dorsally.
Give one structural feature of the avian proventriculus
Macroscopically visible mucosal papillae that secrete HCl into the lumen
What are the three regions of the avian gizzard?
Cranio-dorsal blind sac, Body, Caudoventral blind sac
True or false - ingesta may be passed back and forth between the proventriculus and the gizzard
True
Describe the epithelial histology of the avian gizzard in one sentence
It is composed of glandular mucosa with a thick protective apical layer (the pellicle) of coilin protein to protect the mucosa from abrasive damage.
How might taste buds contribute to innate oral cavity defense in an animal?
The presence of taste buds and sensory innervation in the oral cavity allows animals to detect potentially noxious substances or foreign bodies immediately
Define palatoschisis. What are some potential consequences for the animal?
Failure of complete closure of the lateral palatine processes of the maxillary bone during development. The animal will be unable to generate negative pressure to suckle milk (and starve), and may also aspirate anything that enters the oral cavity, risking aspiration pneumonia. Most cases die shortly after birth.
Define cheiloschisis. Is this condition compatible with life?
Failure of the lateral maxillary bones to fuse to form the philtrum at development. The detriment to the animal depends on the size of the defect - if the animal can still suckle, prognosis is good and it can also be fixed with surgery.
If an animal had brachygnathia superior, you would expect it to have an abnormally _____ ______ and a normal ____ _____?
(short, long, maxilla, mandible)
Brachygnathia superior = short maxilla, normal mandible
If an animal had brachygnathia inferior, you would expect it to have an abnormally _____ ______ and a normal ____ _____?
(short, long, maxilla, mandible)
Brachygnathia inferior = short mandible, normal maxilla
If an animal had prognathia superior, you would expect it to have an abnormally _____ ______ and a normal ____ _____?
(short, long, maxilla, mandible)
Prognathia superior = long maxilla, normal mandible
If an animal had prognathia inferior, you would expect it to have an abnormally _____ ______ and a normal ____ _____?
(short, long, maxilla, mandible)
Prognathia inferior = long mandible, normal maxilla
What does ‘agnathia’ mean?
Absence of a mandible.
Define ‘stomatitis’
Stomatitis = diffuse inflammation of the oral cavity.
Give the clinical term for ‘inflammation of the lips’
Inflammation of the lips = Cheilitis
True or false - ulcers do not extend past the basement membrane.
False. Ulcers represent full-thickness loss of the epithelium including its basement membrane.
Define ‘papule’. What is one disease that characteristically produces papules?
Papule = a raised, flat topped solid lesion, seen in parapox virus infections in sheep (Orf)
Give three clinical signs you might expect in an animal with disease of the oral cavity.
Any of : 1. Anorexia 2. Ptyalism 3. Halitosis 4. Redness, swelling, exudate of the oral mucosa 5. Ulcers, erosions or masses in the oral cavity Possibly also - poor coat due to not grooming
Give one disease that characteristically produces ulcers.
BVD virus, feline calicivirus
Give one disease that characteristically produces vesicular lesions (raised fluid filled lesions < 1cm)
Foot and mouth disease, vesicular exanthema, swine vesicular disease
What are the four major vesicular diseases of domestic animals?
- Foot and mouth disease (pigs and ruminants)
- Vesicular stomatitis (exotic, many species)
- Swine vesicular disease
- Vesicular exanthema (pigs)
Give three locations in the body you might find erosions and vesicular lesions in an animal infected with foot and mouth
Muzzle, oral mucosa, tongue, mammary epithelium, coronary band of hooves
Which viral pathogen is responsible for foot and mouth?
Picornavirus.
Which viral pathogen is responsible for swine vesicular disease?
Picornavirus.
Which viral pathogen is responsible for vesicular exanthema in pigs?
Calicivirus.
What is the difference between superficial and deep stomatidities?
Superficial stomatitis does not affect tissue layers below the mucosa. Deep stomatidities involve connective tissue and beyond.
Name three important ulcerative and erosive diseases in domestic animals.
- Bovine viral diarrhoea virus (Flavivirus)
- Feline calicivirus
- Rinderpest (exotic)
- Bluetongue
True or false - Foot and mouth disease produces a fever and is usually fatal.
False - foot and mouth disease does produce a fever, though it is rarely fatal!
What special diagnostic feature would you look for in a histo sample of a potential pemphigus vulgaris case? What other disease has a similar presentation to this?
This disease involves autoimmune attack on desmosome protein ‘desmoglein’, and it is pathogneumonic to see the topmost cell layers have detached and are ‘floating’ above the deeper layers. Uremic glossitis produces similar gross lesions to this.
Name two important papular stomatidities in domestic animals and their causative agent.
- Bovine papular stomtitis
- Contagious ecythema (Orf)
Both caused by Parapox viral species
Which species is most commonly affected by oral eosinophilic granuloma? Describe two things that may be seen (grossly or histologically)
Cats
- ulceration of oral cavity anywhere from gingiva - pharynx
- yellow specks in mucosa that correspond to microscopic collagenolysis
- eosinophil-rich granulomas seen histologically with giant cells mast cells and multifocal collagenolysis
Which viral infection of cattle often produces linear ulcers down the oesophagus?
BVDV
Which organism often causes oral necrobacillosis? Is there anything that would predipose to this condition?
Fusobacterium necrophorum infection secondary to oral cavity mucosal damage (e.g due to rough feed) is the typical cause of oral necrobacillosis. May also be called calf diptheria in calves.
Which organism is typically responsible for ‘wooden tongue’? Why does the tongue feel so firm?
Opportunistic infection of the oral mucosa by Actinobacillus lignieresii. Once the tongues develop the characteristic granulomatous inflammation, they feel very firm, dry and abrasive. May also produce lumpy jaw.
Which organism is typically responsible for ‘lumpy jaw’? Briefly describe the condition.
Actinomyces bovis infection of the oral cavity typically spreads to bone, causing osteomyelitis. This is typically pyogranulomatous (macrophage and neutrophil rich). The lesions may deform the bone or even fracture the jaw, and may form raised ulcerated lesions visible from the exterior of the animal. Can also produce wooden tongue.
Why are Actinomyces and Actinobacillus infections typically associated with drought?
The excess of abrasive roughage owing to the dry weather can increase the incidence of traumatic oral lesions which predipose to Actinomyces and Actinobacillus infection, as these organisms occur as commensal flora of the oral cavity .
Is fibrous gingival hyperplasia malignant? Which species is most commonly affected?
No, it is a benign overgrowth of the gingiva which can bury the adjacent teeth. Most common in dogs, especially brachycephalic breeds
Define ‘epulides’
Epulides = tumour-like mass on the gingiva. May be benign or malignant.
What is the most common epulis? Is it malignant? Which species usually affected?
Fibromatous epulis is the most common - characterised by submucosal proliferation of fibrous tissue. Is generally benign. Most common in dogs.
What is an acanthomatous epulis? What is the anticipated behaviour of this lesion?
An ancanthomatous epulis is a lesion caused by proliferation of the epithelium in the oral cavity - typically malignant behaviour
In which species is squamous cell carcinoma of the oral cavity most common? What might you see histologically?
Most common in cats, though does occur in dogs. Would likely see thickened epithelial layer on histo, with anaplastic keratinocytes invading submucosal layer
What is the most common oral cavity tumour in dogs?
Melanoma - amelanotic form is especially malignant.
What three some clinical signs you might see in oesophageal disease?
Any of:
- ptyalism
- regurgitation
- dysphagia
- inadequate growth rate in young animals
- weight loss
- aspiration pneumonia
What is megaoesophagus?
Abnormal dilation and flaccidity of the oesophagus. May be congenital (e.g persistent right aortic arch) or acquired (myasthenia gravis). Seen in dogs, cats and horses.
Describe acquired megaoesophagus
Abnormal flaccidity and dilation of the oesophagus due to segmental or diffuse dysfunction of oesophageal musculature. Generally, the oesophagus is uniformly dilated resulting in ventral displacement of the heart upon radiography. Causes include myasthenia gravis, oesophageal stricture secondary to ulcerative disease, snakebite, lead poisoning etc.
Describe congenital megaoesophagus
Potential causes include the persistence of the right fourth aortic arch, resulting in oesophageal stricture in that location, and dilation/flaccidity cranial to that.
What lesions might be grossly obvious due to reflux oesophagitis?
Streaky, red, linear ulcers due to gastric reflux
Give an example of intra-lumenal oesophageal obstruction.
Intralumenal obstructions are due to a FB in the oesophagus such as potato, corn cob. More common in younger, curious animals.
Give an example of mural oesophageal obstruction.
Mural obstructions are those that affect the mucosa to cause scarring and stricture secondary to ulceration e.g healing of a wound from a penetrating foreign body
Give an example of an extramural oesophageal obstruction.
Extramural means something is compressing the oesophagus from the outside such as a tumour in the mediastinum or persistent right aortic arch.
What are three potential consequences of ‘choke’? (in any species)
- Pressure necrosis of the oesophageal mucosa
- Perforation of the oesophageal mucosa
- Healing via fibrosis and therefore stenosis of the oesophagus
Name three common parasites of the oesophagus in domestic species, and briefly describe the lesions.
- Sarcocystis spp. forms nodular white ovoid projections from the muscularis layer
- Gongylonema spp. present as thin, red, serpentine structures beneath the mucosa
- Trichomonas spp. affect birds to cause inflammation and caseous plaques at the mucosal surface
Which parasite is known to induce fibrosarcomas of the oesophagus?
Spirocerca lupi
List some of the features of gastrointestinal smooth muscle that facilitate its autonomous activity
- Desmosomes and gap junctions providing electrochemical and physical connection
- Pacemaker cells with fluctuating membrane potential giving ability to depolarise spontaneously
- Response to factors such as stretch, PNS innervation, local hormonal release
List the three levels of control of GIT motility
- Autonomous activity (initiated within the muscle itself)
- Intrinsic nerve plexus activity (submucosal and myenteric plexuses). Also get modulation via local enterogastrone release.
- Long reflexes (initiated in brainstem)
What are three features of gastric smooth muscle that allows a large increase in contents without a corresponding increase in intralumenal pressure?
- Plasticity of gastric smooth muscle allows stretch to accommodate food without loss of tone
- Rugae can flatten out
- Food ingestion stimulates vagal-mediated ‘receptive relaxation’ of gastric smooth muscle
How is gastric mixing/contraction initiated?
Via pacemaker cells in the fundus. Waves of contraction spread from the fundus to the pylorus
How does the pyloris/pyloric mucosa contribute to gastric food digestion?
- Secretion of mucous to lubricate digesta and protect epithelium
- Thick mucosa grinds particles into small sizes through muscular contraction
- Incomplete constriction of pyloric sphincter to allow only fluid chyme through to the duodenum
- Retropulsion of larger food particles back to the fundus for further digestion
What are three factors that contribute to gastric smooth muscle membrane potential (and therefore contractility)?
- Gastrin release from G cells in pylorus (hormonal)
- Vagal stimulation (neural)
- Stretch of the stomach (mechanical)
What are two stimuli for INCREASED gastric emptying?
- Stretch of stomach
- Fluidity of chyme
- mediated by release of gastrin
What are three stimuli for DECREASED gastric emptying?
- fat in the duodenum (mediated by CCK)
- low pH of the duodenum (mediated by secretin)
- distension of the duodenum
What is the process and purpose of ‘segmentation’ mixing in the small intestine?
Segmentation is mediated by contraction of circular muscles at either end of the bowel section. The movement increases contact of chyme with absorptive surfaces. Get anterograde and retrograde peristalsis within the segment.
What is the difference between ‘Migrating Motor Complexes’ (MMC) and ‘Giant Peristaltic Contractions’ (GPC)?
MMC are of lesser intensity and duration compared to GPC. GPC only occur in the distal SI and colon whereas MMC occur throughout the intestine. GPC are stimulated by gastric distension.
Give an example of a ‘prokinetic’ drug for the GIT and its mechanism of action.
Metaclopramide or domperidone - antagonist for dopamine receptors
or
Cisapride - acts to increase ACh in the synaptic cleft and mytenteric plexus
Give an example of an ‘antispasmodic’ drug for GIT and its mechanism
Hyoscine (buscopan) - AChR antagonist, effective for smooth muscle relaxation
True or false - Intrinsic rumen rhythmicity is initiated by the medulla oblongata in the CNS.
False
True or false - the rumen receives some contractile stimulus from the CNS
True
Which extrinsic nerve fibres are important in strong rumen contractions?
Vagal and splanchnic
What are the two mechansims that contribute to the low-amplitude rhythmic contractions of the rumen?
- Intrinsic myogenic contractions via spontaneous smooth muscle cell depolarisation
- Intrinsic neurogenic contractions mediated by the myenteric plexus
Are intrinsic myogenic contractions of the rumenal smooth muscle likely to respond to pharmacological blockade e.g beta-adrenergic blockers
No. Intrinsic neurogenic contractions are, however.
Which sensory receptors are involved in initiating the oesophageal groove reflex (reticulo-omaso-abomasal groove)
Mechanoreceptors and taste receptors in the buccal and oral cavities
True or false - the oesophageal reflex can be inhibited by ganglionic blocking drugs (inhibiting vagal stimulation)
True. The oesophageal reflex is controlled by the vagus nerve.
What must a ruminant achieve before it can propel a bolus of food UP the oesophagus for further mastication?
Negative pressure must be generated in the thoracic cavity relative to the rumen, to assist the bolus up the oesophagus. The animal does this by inspiring against a closed glottis to lower the pressure in the thoracic cavity. Reverse peristalsis then takes over.
In a cow, what effect might stretch and tactile stimulation of the oesophagus have on the salivary glands and rumen?
- increase in salivary flow rate
- increased frequency of reticulorumenal contractions
- requires vagal input
What is one stimulus for eructation contraction sequence?
Gaseous distension of the rumen. Requires vagal input.
What effect will a high concentration of VFAs and lactic acid in the rumen have on motility?
Inhibition of rumen motility.
What effect will distension of the omasum have on reticulorumen contractions?
Reduction in magnitude and frequency. Requires vagal input.
What effect will increase HCl concentration and tactile stimulation of the abomasum have on reticulorumen contractions?
Increase in magnitude and frequency. Requires vagal input.
What effect will duodenal distension have on reticulorumenal contractions?
Reduction in magnitude and frequency. Requires vagal input.
Describe the composition, function and regulation of parotid saliva in the ruminant
High in HCO3-, low in protein, no enzymes.
Functions to buffer acid produced through microbial fermentation in the rumen and recycle water and electrolytes within the animal (reduces the amount of water that must be consumed by the animal by recycling it)
Secreted constitutively though flow rate increased by PNS stimulation
Describe the composition, function and regulation of submandibular saliva in the ruminant
Mucous and protein rich, no enzymes. Hypotonic.
Functions to lubricate food
Both SNS and PNS stimulation increase flow rate though SNS also increases the mucous composition.
Explain the regulation of salivary flow rate in the ruminant
- Autonomic stimulation increases flow from both parotid and submandibular glands
- Mastication and tactile stimulation in the oesophagus and reticulorumen stimulate parotid release
- Tactile stimulation in the buccal area, oesophagus and reticulorumen stimulate submandibular release
What effect might reduced rumenal fluid volume have on the ruminant?
Reduced efficiency of digestion, loss of body condition
What effect, if any, will cholinergic agonists have on intrinsic neurogenic contractions of the rumen?
Increase in magnitude.
Prior to true vomiting, what symptoms might be seen?
Pallor, excess salivation, increased HR
What drives retrograde passage of vomitus up the oesophagus during vomiting?
A marked increase in intra-abdominal pressure (caused by contraction of the diaphragm and abdominal muscles) combined with reduced intrathoracic pressure (caused by inspiration against a closed glottis)
Blood-bourne toxins cause vomiting via stimulation of the CRTZ. Which pro-emetic drug also works in this way?
Apomorphine - this is a centrally-acting emetic.
May renal failure cause vomiting via CRTZ stimulation, direct stimulation of the emetic centre, or both?
May cause vomiting via both pathways.
How might abnormal motion cause vomiting? Explain the mechanism. What drug might inhibit vomiting caused this way?
Abnormal motion is detected by the vestibular apparatus in the inner ear, and the information relayed to the emetic centre via both the CRTZ and higher centres. These cells express a histamine receptor, and the drug promethazine may be used to inhibit the cells’ signalling.
What is the mechanism of action for ondansetron? For which stimuli is it most effective?
Ondansetron is an anti-emetic that inhibits 5HT3 receptors. These are found in the gut, the CRTZ and at the emetic centre. As such, ondansetron is effective for vomiting induced by dietary indiscretion (or parvovirus infection) and circulating noxious stimuli e.g chemotherapeutic drugs.
What is maropitant?
What is its mechanims of action? Where are the receptors located?
Maropitant is an anti-emetic that acts as a competitive antagonist at NK1 receptors, found in the CRTZ and at the emetic centre. These are normally activated by substance P.
True or false - regurgitation involves a wave of retrograde peristalsis.
True.
How do peripherally acting emetics work? Provide an example.
Works by stimulating irritation of the gastrointestial mucosa to activate afferent pathways to the emetic centre to cause emesis. E.g washing soda
What are the two important functions of metaclopramide in relation to the gastrointestinal system?
- Promotes GIT motility through promotion of ACh signaling
2. Inhibits CRTZ activity and therefore emesis through inhibiting dopamine signaling
Which is the major neurotransmitter used by the cerebral cortex to stimulate the emetic centre?
Acetylcholine
What are some potential side effects of metaclopramide use?
Due to inhibition of dopamine signaling in the CNS, might see hyperactivity, depression, disorientation, frenzy
What might occur as a result of excessive hyoscine usage?
Atony of the GIT smooth muscle, which can be a stimulus for vomiting in itself. May also get absorption of bacterial endotoxin through mucosal barrier due to slow passage rate.
What are the four aims of laxative drugs?
- Increase bulk of large intestine content
- Soften large intestine content
- Increase water content in large intestine
- Increase propulsive contractions of the large intestine
Name two laxative drugs
Any of:
- wheat bran
- lactulose
- magnesium sulphate
- senna
Name two drugs that might be used to reduce diarrhoea. Is there any associated risk with their use?
Opioids - codeine and loperamide. They may cause habitation and side effects.
What are three structural features of the gastric epithelium that contribute to its HCl tolerance?
- Tight junctions between the columnar epithelial cells prevents much of the H+ ion backflow into the tissues
- Protective glycocalyx layer formed via secretion of HCO3-
and mucous by the columnar cells and mucous cells - Good blood supply washes away most leaked H+ to prevent local damage
What are three specialisations of the parietal cell that facilitate HCl secretion?
- Deep apical membrane infoldings (secretory canaliculi) increasing SA for secretion
- Ability to translocate intracellular tubules and vesicles to form apical microvilli to further increase SA for secretion
- Abundant mitochondria to generate sufficient ATP to power apical H/K ATPase and basolateral HCO3-/Cl- exchanger
Relate the histological appearance of the gastric chief cell to its function
Has basophilic colour due to bountiful RER and ribosomes. Chief cells synthesise a great deal of pepsinogen (i.e protein)
What are the secretory compenents of gastric juice?
HCl, pepsinogen (cleaved to pepsin in the lumen via HCl), mucous, HCO3-
What effect does caffeine have on HCl secretion? What is the mechanism?
Caffeine inhibits phosphodiesterase which causes prolonged increase in cAMP concentrations within the parietal cell. cAMP stimulates the H/K ATPase therefore caffeine causes extended HCl secretion.
What effect does histamine have on HCl secretion? Where does local histamine come from? What are the two mechanisms that stimulate local histamine release?
Histamine signaling the parietal cell causes an increase in intracellular cAMP and stimulates HCl secretion. Histamine is released locally by enterochromaffin-like cells in response to ACh stimulation and gastrin signaling.
What does the drug misoprostol do to HCl secretion? What is the mechanism? Does it have any other effects?
Misoprostol is a prostaglandin E2 analogue. It acts at the parietal cell to reduce intracellular cAMP levels and therefore reduce HCl secretion.
Also stimulates mucosal cell turnover, mucous secretion and bloodflow to the gastric mucosa (like endogenous PGs)
List the stimuli for pepsinogen release by chief cells.
Gastric mechano- and chemo-receptor signalling in response to protein within the lumen
HCl in the lumen
Direct vagal efferent stimulation
What stimulates secretin release? What is its effect on HCl secretion?
low pH in the duodenum - secretin inhibits HCl secretion
What stimulates CCK release? Which cells release it? What are some of its effects?
CCK release from enterochromaffin cells is stimulated by presence of lipids in the duodenum. CCK acts to: inhibit HCl secretion, inhibit gastric emptying, elicit gall bladder contraction and pancreatic enzyme release
What stimulates release of gastric inhibitory peptide? What is its effect?
GIP is released by EC cells in the intestinal wall in response to lipids and CHOs in the lumen. Acts to inhibit gastric emptying.
How is gastrin secretion by G cells regulated?
Gastrin secretion by G cells is inhibited by pH < 2 in the lumen
What are some examples of H2 receptor antagonists? What is their function and clinical significance?
Cimetidine, ranitidine. Block histamine signaling the H2 receptor on parietal cells. Produce partial inhibition of HCl secretion (~70%). Good specificity as H2 receptor only located on the parietal cell
Reduced bloodflow to the stomach can lead to gastric ulceration. Name three things that can do this.
Shock, GDV, NSAID use, hyperadrenocorticism, mast cell tumour
What are examples of proton pump inhibitors? How effective are they at inhibiting HCl secretion?
Omeprazole and pantoprazole - permanent block of H/K ATPase. Produces 90% block.
What is the mechanism of action for sucralfate?
Sucralfate is known as a cytoprotective agent -
dissociates in the gastric lumen to octosulfate, a sticky sucrose gel + aluminium hydroxide which neutralises HCl to protect the gastric mucosa
What is the approximate length of the duodenum in the dog? Which section of the duodenum is the longest?
Around 25cm long; the descending section is the longest
In the dog - relative to the descending duodenum, the right pancreatic lobe is ____ and the jejunal mass is ___. (ventral/dorsal/medial/lateral)
Relative to the descending duodenum, the right pancreatic lobe is dorsal and the jejunal mass is ventral.
The duodenum passes ____ to the root of the mesentery in the dog?
Dorsal (behind)
The mesoduodenum tightly anchors which portion of the duodenum to the body wall in the dog?
The ascending duodenum.
It becomes progressively tighter the closer to the caudal flexure it is.
Which structures are to the left and the right of the ascending duodenum in the dog?
To the left = the descending colon
To the right = the root of the mesentery
True or false - for the majority, the duodenum sits behind the greater omentum.
False. It only dives into the mesentery when it becomes the jejunum
What structures does the hepatoduodenal ligament contain?
The bile duct, the portal vein and the hepatic artery
What is the duodenal papilla situation in the dog?
Major papilla - bile and pancreatic ducts
Minor papilla - accessory pancreatic duct (actually larger in dog)
The pancreas in the dog occurs _______ to the pylorus of the stomach? (direction). The R lobe is adjacent to the _____, and the L lobe is adjacent to the _____.
The pancreas in the dog occurs caudo-medial to the pylorus of the stomach. The R lobe is adjacent to the duodenum, and the L lobe is adjacent to the greater curvature of the stomach.
In the dog, which duct receives pancreatic secretions from the dorsal primordium (right lobe)?
The accessory duct. The major duodenal papilla receives secretions from the ventral primordium (left lobe).
Which surface of the dog pancreas is crossed by the portal vein?
The dorsal surface
Approximately how long is the duodenum in the cat?
10cm
What is the duodenal papilla situation in the cat?
They have one, which contains the common bile duct and single pancreatic duct openings.
The pancreas is supplied by the cranial and caudal pancreaticoduodenal arteries. Which arteries do THESE branch off?
Cranial PDA = branch of celiac artery
Caudal PDA = branch of cranial mesenteric artery
