Goff Study Questions Flashcards
Cations added to the blood cause the blood pH to change- in which direction. If a dog is exhibiting acidosis and blood bicarbonate is higher than normal, what kind of acidosis would this suggest was occurring (metabolic or respiratory)? If the kidneys are putting out urine with a pH of 5.3 would that be contributing to the acidosis or a compensatory mechanism in this dog? What if blood potassium was 8 mEq/L?
A. Adding cations will cause the blood to become more alkaline.
B. Respiratory acidosis – if the body was compensating using the respiratory system, bicarb would be lowered to promote respiratory alkalosis.
C. The urine would be compensatory because it is removing anions, reducing pH of the blood.
D. If the potassium is 8 mEq/L it is compensatory for the acidotic state.
Which sections of the GI tract are innervated by pelvic parasympathetic neurons?
The second half of the colon, the rectum, and the bladder.
It’s been a wet year. A horse is exhibiting severe drooling. You notice its hay has some red clover in it and is a bit moldy. What is going on? Give mechanism!!
The horse is exhibiting Slaframine Slobbers from the mold, Rhizoctonia leguminicola. The mold has parasympathomimetic effects. The horse can drool up to 10 gallons per day.
Anesthetics tend to depress the heart rate of dogs. If I give a dog atropine or glycopyrolate prior to induction of anesthesia would I increase or decrease the risk of saliva being aspirated during anesthesia? Cows salivate a lot!! If I was doing standing surgery in a cow under local anesthesia with Rompun (xylazine) a sedative that causes drooling (don’t worry about how Rompun does this- this year!!), could I give her atropine for the same reasons? Any health risks??
Atropine blocks muscarinic receptors on target tissues (salivary glands) which inhibits Ach, produced by postganglionic parasympathetic neurons, from binding to these receptors. This would decrease the risk of saliva being aspirated during anesthesia. It also increases the heart rate (blocked vagus signals). Additionally, a potential health risk could be that the cow would be unable to eructate causing bloat and death. The whole reflex is removed.
What is the purpose of the intercalated duct of a salivary gland? What do the ductal cells secrete? When and what stimulates them to secrete?
A. They form the duct leading from the acinus to the striated duct. They form part of the intralobular duct.
B. They secrete electrolytes.
C. Beginnings of digestion cause them to secrete to begin starch and fat digestion along with reducing osmolarity.
D. Note: the striated ducts were more focused on and they produce and alkaline solution to put into the saliva and buffer the stomach acid.
A rabbit comes into your office with wet matted hair on its chest and has maggots in the area around its anus. What is a likely cause of this and why???
Malocclusion and resultant spurs make the rabbit too uncomfortable to groom and cause slobbers. As a result, the rabbit becomes unclean and has a wet chest. Flies will use this as an opportunity to lay eggs, and the condition is called Flystrike.
Why do old horses need their teeth floated? What are the repercussions of not having good teeth to the horse? Why do a horse’s molars stay sharp on the occlusal surface? How come your dog’s molars don’t?
Horse teeth are constantly erupting through the gum line and the equine upper arcade is more laterally extending than the lower arcade. This results in the development of labial and buccal sharp points, which cause the development of ulcers. If your horse does not have good teeth, they can lose weight drastically and may be unable to hold food in their mouth in addition to the painful ulcers. Behavior will also likely change, especially in response to a bit pressing against the ulcers. A dog will not experience this because of the difference in how the occlusal surfaces meet and how they chew – horses grind their food side to side while dogs only use their molars to break off chunks or crush food.
A cow spends 7-10 hrs a day chewing. How is it possible for the cow to accidentally ingest a piece of wire?? Why is the horse less likely to ingest a piece of wire?
Cows will eat as fast as possible, swallow, and regurgitate their food later. They’re not picky and will eat most anything. Horses spend all day browsing and will avoid toxic or inedible items in addition to chewing their food at the time of picking it up to eat.
Your client is having trouble pilling his cat. What does he need to do to ensure the cat swallows the pill? Explain the swallowing reflex! What could happen if I give oral liquids into the mouth (drench) of a cow with clinical hypocalcemia and weakness??
The client must push the pill to the back the pharynx where swallowing becomes an involuntary reflex. The pharynx senses using nerves V, IX, and X then responds with efferent VII, IX, X, and XII to initiate the reflex. The back of the tongue and floor of the mouth will elevate to drive the bolus back, and then the dorsal soft palate will elevate to close the nasopharynx. The hyoid will elevate, the epiglottis will move downward, and the laryngeal muscles will close the glottis. The upper esophageal sphincter will relax to allow the bolus into the esophagus and the vacuum within the esophagus will draw food in.
The oral liquids would take too long to absorb which is why IV calcium is needed to treat milk fever cows.
Explain the difference between intrinsic and extrinsic control of gut functions. Diagram a local reflex response to stretching of a segment of gut contained entirely within the Enteric nervous system.
Extrinsic control of the gut is done by the vagus – afferent signals must travel all the way to the medulla and parasympathetic efferent response occurs.
Intrinsic control is specific to the enteric nervous system. Afferent signals from chemoreceptors and stretch mechanoreceptors send signals to the submucosal and myenteric plexi, which the send efferent responses back which control secretion, peristalsis, and mixing movements.
What is the path of the vagus nerve? Are there any other sources of parasympathetic innervation to the GI tract? Where are cell bodies of pre and post-ganglionic fibers of the sympathetic and parasympathetic system affecting the stomach and intestines located?
Sympathetic: Spinal cord nerve cell bodies are in the section of T2 – L3. Axons come out of the spinal cord, to the sympathetic chain and then to ganglia. At the ganglia, the pre-ganglionic meets the post-ganglionic and acetylcholine is released to the nicotinic receptor. The post-ganglionic releases acetylcholine to nicotinic receptors.
Parasympathetic: Nerve bodies are found in the sacral spinal cord and medulla. The vagus nerve parasympathetic will travel from the medulla, traveling with the vagus into the thoracic cavity and then into the abdominal cavity through the esophageal hiatus.
- Where is the myenteric nerve plexus? Where is the submucosal nerve plexus.. Diagram a reflex response to stretching of a segment of gut that involves the autonomic nervous system plus the Enteric nervous system
The myenteric plexus is found between the circular and longitudinal muscle layers while the submucosal nerve plexus is found between the mucosa and circular layer.
Where are muscarinic receptors located, and what do they respond to? Where are nicotinic receptors located, and what do they respond to? Name an antagonist of the nicotinic and an antagonist of muscarinic receptors.
Muscarinic receptors are located in the target cells of the parasympathetic system.
Nicotinic receptors are located on both sympathetic and parasympathetic post-ganglionic nerve cell bodies.
They all recognize acetylcholine. An antagonist of muscarinic receptors is atropine and an antagonist of nicotinic receptors is curare.
- What do you think you might see in a horse that has broken out of its fenced area and gotten into seed corn coated with an organophosphate poison? WHY?
The horse will exhibit excessive drooling, diarrhea, constricted pupils, and other symptoms. This is because of an inability to break down Acetylcholine, causing an increase in parasympathetic stimulation. There is technically an increase in both parasympathetic and sympathetic responses, but the parasympathetic response dominates.
- What are borborygmi? Where can I best listen for them in the horse and what should they sound like – what frequency? What do I hear if there is intestinal stasis? What should you hear when you put your stethoscope in the left paralumbar fossa of a cow? How often?? Where do I put the stethoscope to hear the reticulum?
A. Borborygmi are rumbling sounds made by gas passing through the small intestine or colon. They’re really useful to listen to in the equine large intestine.
B. You should listen for loud booming gurglings of the colon and cecum that reach peak intensity every 15-20 seconds. Listen to them on the right flank.
C. In early stages of spasmodic colic, they become more crackly and loud. In stasis, the sounds quit. With blockages, you might hear a trickling sound of fluid dropping out of the ileocecal valve through empty space into the cecum.
D. In a cow, you should hear three mixing contractions every two minutes. It’s a gurgling sound coinciding with a slight lift to your hand in the flank and then followed by a second more pronounced lift of the flank and a booming sound of gas moving.
E. To hear the reticulum, listen to the lower left ribs.
Which enzymes are present in saliva? What do they do?
Salivary amylase – Starch digestion
Salivary lipase – Fat digestion
There are also lysozymes, water, and alkaline buffers in saliva. The alkaline buffers come from the striated duct cells.
What is the difference between segmental and peristaltic contractions of GI tract? What is the difference between a short (inches) and a long (feet) peristaltic contraction -ie in terms of how this is controlled?
Segmental type contractions of the GI tract result from the constriction of circular muscle close to the lumen, which divides the gut into dilated segments containing ingesta. The dilated and constricted segments swap, mixing and circulating the ingesta. This is largely stimulated by stretch.
Peristaltic contractions are a moving ring of luminal constriction preceded by areas of luminal distension. The area of constriction is created by contractions of circular muscle and areas of dilation are created by contraction of longitudinal muscle. Net action propels ingesta.
Long peristaltic contraction requires parasympathetic input from the vagus nerve while short contractions are a local reflex involving the enteric nervous system. Dogs and cats can evacuate their colon in one single constriction using the parasympathetic long peristaltic contraction.
Why and how does my stomach grumble when I am hungry? Where does contraction of the stomach begin? What factors determine speed and strengthen stomach contractions? What factors diminish them? What determines the fastest rate at which the stomach can contract?
A. Your stomach is grumbling because it is constantly contracting and mixing the contents in it. It is louder when you are hungry because it is less muffled by contents. Additionally, higher centers in the brain in response to sight, smell, or taste of food can initiate vagal parasympathetic stimulation of stomach contractility.
B. Contraction of the stomach begins mid-fundus. Distension of the fundus activate the stretch receptors, causing the activation of peristaltic contractions beginning mid-fundus and moving toward the pylorus. As peristaltic waves reach the pylorus, a small amount of chime is expelled into the duodenum.
C. Gastrin stimulates stomach motility along with vagal parasympathetic stimulation. Emptying is spurred by increased vagal tone in response to increased distension pressure in the stomach. Emptying is slowed by decreased vagal tone, Cholecystokinin (fat enters duodenum), and Secretin (pH drops in duodenum).
D. Contraction and relaxation of the pyloric sphincter determines the rate of emptying of the stomach
You get a call one evening just as you open a beer after supper. “My dog just ate a bottle of grape flavored children’s Tylenol!” Its 30 min to your clinic and this appears to be a lethal dose of Tylenol. What would you advise?
Give the dog a dose of hydrogen peroxide or salt to induce vomiting.
