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167 Cards in this Set
- Front
- Back
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Cardiac cycle |
One cycle of atrial and ventricular contraction and relaxation is a cardiac cycle. The cardiac cycle produces one heart beat. |
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Depolarization |
In order for the cell to contract it must depolarize. |
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Repolarization |
When the cells in the heart are relaxing |
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Systole |
Is the myocardium contracting, causing a chamber to empty itself of blood. This is the working phase of the cardiac cycle when the cardiac muscle cells are depolarized. |
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Diastole |
Is the myocardium relaxing and repolarizing after a contraction, allowing the chambers to fill with blood again. This is the resting phase of the cardiac cycle. |
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Cardiac conduction system |
Each chamber goes through systole and diastole, but not all at the same time. |
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Normal Heart Sounds |
The heart valves snapping shut produce the heartbeat sound. One cardiac cycle produces two distinct heart sounds. Described as "lub" "dub". The first sound "lub" is produced when the AV valves snap shut after atrial systole. The second heart sound, "dub" is produced after ventricular systole when the pulmonary and aortic valves snap shut. Most heart sounds are best heard on the left side of the standing animal (P,A,Mitral). The tricuspid valve is heard on the right side. |
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Abnormal Heart Sounds |
If the two AV valves or the two semilunar valves are not closing simultaneously you may hear extra heart sounds. |
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Valvular insufficiency |
Is a heart condition where one or more of the cardiac valves dont close all the way. When this happens a murmur is produced. The murmur sound is produced by turbulence in the blood flow and sounds like a swishing or whooshing sound. In the case of valvular insufficiency the murmur is caused by blood backflowing abnormally into a chamber. |
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Valvular Stenosis |
Is a heart condition where any one or more of the cardiac valves dont open all the way. Again a murmur is produced by turbulent blood flow. In the case of valvular stenosis the murmur is caused by blood flowing through a partially open valve and producing the same whooshing or swishing sound. |
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Cardiac Output (CO) |
Is the volume of blood that is ejected out of the left ventricle over a unit of time, usually 1 minute. In a healthy animal the cardiac output has to be sufficient to supply oxygen and nutrients throughout the animals body. 2 factors determine C.O 1. Stroke Volume (SV) 2. Heart Rate (HR) |
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Stroke Volume (SV) aka Systolic Discharge |
Is the volume of blood ejected from the left ventricle during one contraction or systole. |
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Heart Rate (HR) |
Is the number of times the ventricle contracts or beats in 1 minute. |
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Calculation of Cardiac Output |
Cardiac Output (CO) = stroke volume (SV) X heart rate (HR) |
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Heart Rate |
The normal heart rate for each species of animal is set internally by the rate of spontaneous SA node depolarization (Impulse) |
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Blood Vessels |
All blood vessels are arteries, veins, or capillaries. They are hollow tubes with similar but not identical anatomy and function. The walls of arteries and veins have 3 layers. The inner layer that lines the lumen of the vessel is the endothelium. The middle layer of a blood vessel wall is made up of smooth muscle, elastic fibers or both. The outer layer of a blood vessel is composed of fibrous connective tissue and collagen fibers. |
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Endothelium |
It is composed of thin, smooth simple squamous epithelium and is continuous with the endocardium that lines the chambers of the heart. The endothelium provides a smooth surface for the vessel lumen so blood flows easily through the vessel with little or no friction. |
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The middle layer of blood vessel |
Made up of smooth muscle, elastic fibers or both. The smooth muscles contract and relax to change the diameter of the vessel. The elastic fibers provide stretchability to the vessel wall. They allow the blood vessel to stretch and recoil without outside control. |
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Outer layer of blood vessel |
Composed of fibrous connective tissue and collagen fibers. The connective tissue is strong and flexible which prevents vessel walls from tearing. The collagen fibers extend outward from the connective tissue and anchor the vessels so they cant move around too much. Also help keep the lumen of the vessels pulled open. |
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Arteries |
Carry blood away from the heart. In the pulmonary circulation they carry deoxygenated blood to the lungs for oxygenation. In the systemic circulation they carry oxygenated blood throughout the animals body. 2 types of artery: 1. Elastic Arteries 2. Muscular Arteries. |
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Elastic Arteries |
Have the greatest ability to stretch when blood passes through them because they have a large number of elastic fibers in the middle layers of their wall. These arteries are found closest to the heart because they have to be able to stretch and recoil without damage each time a surge of blood is ejected from a ventricle during ventricular systole. The aorta is the largest elastic artery in the body. |
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Muscular Arteries |
Have more smooth muscle fibers than elastic fibers in their walls. They are found farther away from the heart than elastic arteries and usually direct blood to specific organs and tissues. Muscular arteries branch into arterioles. |
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Arterioles |
Are the smallest branches of the arterial tree. They are small muscular arteries and have narrowest diameter. |
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Capillaries |
Arterioles branch into many microscopic blood vessels called capillaries. Capillaries do not occur singly but in groups called capillary beds. One arteriole will give rise to an entire capillary bed. The wall of a capillary is one endothelial cell thick. For this reason the exchange of gases and nutrients takes place at this level |
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Venules |
In order to get the blood back to the heart the capillaries join together to form tiny veins called venules. In the pulmonary circulation the venules carry oxygenated blood; in the systemic circulation they carry deoxygenated blood and waste materials. |
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Vains |
Venules join together to form veins. As veins approach the heart they become larger in diameter. The largest vein in the animals body is the vena cava, and all other systemic veins drain into it. Veins work against gravity to get the blood back to the heart. Small and medium veins have valves in their lumen. The valves allow blood to flow in one direction. Muscular movements in the body compress small veins and the one way valves allow blood to move only toward the heart. |
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Pulse |
The rate of alternating stretching and recoiling of the elastic fibers in an artery as blood passes through it with each heartbeat. The artery has to stretch and recoil because the left ventricle doesnt eject blood in a continous flow. Lg animals have slower pulse rates and smaller animals have faster pulse rates. |
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Pulse Wave |
Every time the left ventricle contracts (systole) it ejects a bolus of blood into the aorta. When the left ventricle relaxes (diastole) blood flow into the aorta stops. Stretching and recoiling that travels through all the arteries and arterioles and dissipates in the capillaries. Pulse is used to evaluate regularity of pulsation and strength. Pulse and heartbeat are not the same thing. |
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Pulse points |
The pulse rate and the heart rate should be equal. |
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Blood pressure |
Is a measure of the amount of pressure flowing blood exerts on arterial walls. It is dependent on the interaction between the heart rate, stroke volume, the diameter and elasticity of the artery, and the total blood volume. |
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Systolic blood pressure |
Blood pressure varies during the cardiac cycle. If youve ever had you blood pressure measured you know that two numbers are recorded. This is the highest number. It is produced by ejection of blood from the left ventricle into the systemic circulation by way of the aorta. |
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Diastolic blood pressure |
The second number, the lowest number of blood pressure. It measures the pressure remaining in the artery during left ventricular diastole when the ventricle is relaxing and refilling with blood. |
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Mean Arterial pressure (MAP) |
A third value is sometimes measured. This is the average pressure during one cardiac cycle. The MAP can be used when monitoring an anesthetized animal as an indication of tissue perfusion. |
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Cardiovascular Monitoring |
Given that the heart is not visible by direct observation, a number of direct and indirect tests have been developed to monitor it and the entire cardiovascular system. - Auscultation of the thorax to determine heart rate and rhythm, and to detect heart murmurs. - Peripheral artery palpation to evaluate the rate, regularity, and strength of the pulse. - Measuring blood pressure to evaluate C.O - Thoracic radiography to evaluate the size and position of the heart. (X Ray) - Electrocardiography to evaluate the electrical activity of the heart (EKG) - Echocardiography tto evaluate the size, shape and movement of heart structures. (Ultrasound) |
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Electrocardiography |
Electrocardiography produces an electrocardiogram (ECG or EKG) based on the electrical activity of the heart. The electrical impulse that originates in the SA node and spreads through the cardiac conduction system can be detected on the surface of the animals body. When the EKG machine is turned on, the electric impulses generated in the heart muscle are picked up at the various locations on the body surface. A series of heartbeats are followed |
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P wave |
- Is the time it takes the wave of depolarization (contraction) to travel from the SA node through the atria. - It corresponds to the mechanical activity of atrial contractions in a normal animal |
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QRS Complex |
- Is the time of ventricular depolarization (contraction) - It corresponds to the mechanical activity of ventricular contraction. - composed of 3 diff. waves - Q wave corresponds to depolarization of the interventricular septum. - R wave corresponds to depolarization of the main mass of the ventricles so it is the largest wave. - S wave corresponds to the final part depolarization of the ventricles near the base of the heart |
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T Wave |
- Is the time of ventricular relaxation (repolarization) - It corresponds to the time taken by the ventricles to get ready for the next contraction by refilling with blood from the atria |
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Echocardiography |
Another way to evaluate the heart is through echocardiography (ECHO or cardiac ultrasound). This procedure uses ultrasound to bounce sound waves off parts of the heart to watch the heart beating. ECHO can be used to evaluate the size, shape, and movement of the heart and its parts. |
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Blood circulation in the fetus |
The major difference between a fetus and a newborn is that the newborn receives oxygen through its own lungs, and a fetus receives oxygen from the blood of its mother. The lungs are not in use and it only needs blood to keep lungs alive. The fetus receives oxygen through the placenta, an organ containing a network of tiny blood vessels that allows oxygen exchange between fetal and maternal circulation. |
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Umbilical Vein |
The oxygenated blood from the mother flows from the placenta into the fetus through the umbilical vein. |
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Foramen Ovale |
The first bypass is the foramen ovale between the right and left atria. Much of the blood from the right atrium flows directly into the left atrium, but some does flow through the tricuspid valve into the right ventricle and then into the pulmonary artery. |
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Ductus Arteriosus |
Blood from the pulmonary artery may flow into the lungs or through another bypass, the ductus arteriosus, directly into the aorta. Remember that this blood was oxygenated when it passed through the placenta. |
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Respiration |
The process of bringing oxygen from outside air in to all of the bodys cells, and carrying carbon dioxide out in the opposite direction. |
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The 2 steps of respiration |
- External Respiration - Internal Respiration |
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External Respiratioin |
Occurs in the lungs. It is the exchange of oxygen and carbon dioxide between the air inhaled into the lungs and the blood flowing through the pulmonary capillaries. |
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Internal Respiration |
It occurs all over the body. It is the exchange of oxygen and carbon dioxide between the blood in the capillaries all over the body (systemic capillaries), and all o f the cells and tissues of the body. |
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Structure of Respiratory System |
Structurally, the respiratory system consists of the lungs and a system of tubes that connects them witht the world outside. - Upper Respiratory - Lower Respiratory |
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Upper Respiratory |
All of the air that enters and leaves the lungs does so through the U.R. structure. We classify all the respiratory structures outside the lungs as parts of the upper respiratory tract which include: - Nostrils - Nasal passages - Pharynx - Larynx - Trachea |
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Lower Respiratory Tract |
All of the structures within the lungs are parts of the lower respiratory tract which include: - Bronchi - Bronchioles - Alveolar ducts - Alveoli It includes all the air passageways in between. All the structures of the lower portion of the respiratory tract are located within the lungs. |
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Nose |
The nose is the first structure where air is inhaled. It begins with the nostrils, aka nares. The nostrils are the external openings of the respiratory tube, and they lead into the nasal passages. |
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Nasal Passages |
The nasal passages are located between the nares (nostrils) and the pharynx (throat). |
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Nasal Septum |
A midline divider called the nasal septum separates the left nasal passage from the right, and the hard and soft palates separate the (dorsal, top) nasal passages from the (ventral, bottom) mouth. |
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Turbinates aka Nasal Conchae |
The nasal passages are convoluted and full of twists and turns because of turbinates. Turbinates are thin, scroll like bones covered with nasal epithelium and occupy most of the nasal passages. |
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Nasal Meatus (passageway) |
Two sets of scroll like turbinates are found in each nasal passage: a dorsal turbinate and a ventral turbinate. They divide each nasal passage into 3 main passageways: - Ventral nasal meatus - Middle nasal meatus - Dorsal nasal meatus |
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Ventral nasal meatus |
located between the ventral turbinate and the floor of the nasal passage. |
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Middle nasal meatus |
Located between the two sets of turbinates |
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Dorsal nasal meatus |
Located between the dorsal turbinate and the roof of the nasal passage. |
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Lining of nasal passageways |
Nasal passages is critical to their function. It consists of pseudostratified columnar epithelium with cilia projecting from the cell surfaces up into a layer of mucus. An extensive complex of large blood vessels lies just beneath the nasal epithelium. |
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Nasals main function |
Nasals main function is to condition the inhaled air that passes through them. The 3 main conditioning roles are - warming = by the blood flowing beneath nasal epithelium - humidifying = by the mucus and other fluids that lie on the epithelial surface - filtering = by the many twists and turns produced by the turbinates the inhaled air. |
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Sense of smell aka Olfactory sense |
These are receptors for the sense of smell |
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The sinuses aka Paranasal sinuses |
They are outpouchings of the nasal passages that are contained within spaces in certain skull bones. Each sinus is named for the skull bone that houses it. The sinuses have ciliated lining constantly sweeping mucus down into the nasal passageways. |
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The Pharynx aka (Throat) |
Nasal passages lead back to the pharynx. It is a common passageway for both respiratory and digestive system. At its rostral (front) end, the soft palate divides the pharynx into the dorsal nasopharynx (respiratory passageway) and the ventral oropharynx (digestive passageway). At its caudal end the pharynx opens dorsallly into the esophagus (digestive passageway) and ventrally into the larynx (respiratory passageway). |
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The Larynx aka Voice Box |
It connects the pharynx with the trachea. It is made up mainly of segments of cartilage that are connected to each other and the surrounding tissues by muscles. The larynx is supported in place by the hyoid bone. The major cartilages in common are: - epiglottis (1) - artenoid cartilages (2) - thyroid cartilages (1) - cricoid cartilage (1) Of these, epiglottis and the arytenoid cartilages are most commonly of clinical importance. |
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Epiglottis |
Somewhat leaf shaped epiglottis is the most rostral of the laryngeal cartilages. When the animal swallows, the epiglottis covers the opening of the larynx. This keeps swallowed material out of the larynx and into the esophagus. |
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Vocal cords |
They are attached to the two arytenoid cartilages. Muscles adjust the tension of the vocal cords by moving the cartilages. The arytenoid cartilages and the vocal cords form the boundaries of the glottis, the opening into the larynx. |
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Voice Production aka Phonation |
The basic sound of an animals voice originates from the vocal cords in the larynx. These two fibrous connective tissue bands are attached to the arytenoid cartilages and stretch across the lumen of the larynx. As air passes over the taut vocal cords, they vibrate and produce sound. The muscles that attach to the arytenoid cartilages control the tension of the vocal cords. Coughing and straining the closed glottis. |
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Functions of the larynx |
- Part of the upper airway - Voice production - Prevention of foreign material being inhaled = by the epiglottis - control of airflow to and from the lungs = by the epiglottis |
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Trachea aka Windpipe |
Is short, wide tube that extends from the larynx down through the neck region into the thorax, where it divides into the two main bronchi that enter the lungs. This division, called the bifurcation of the trachea occurs at about the level of the base of the heart. It is a tube of fibrous tissue and smooth muscle held open by hyaline cartilage rings. It has a ciliated lining and a mucus layer to help clean the air. |
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Main part of the trachea |
The main part of the trachea forms the base of the Y, and the bifucation forms the arms of the arms of the Y (Left and Right main bronchi that enter the lungs). |
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Tracheal Rings |
Incomplete rings of hyaline cartilage spaced along the length of the trachea prevent it from collapsing. Each tracheal ring is C Shaped with open part of the C facing dorsally. The gap between the ends of each ring is bridged by smooth muscle. |
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The bronchial Tree |
The air passageways that lead from the bronchi to the alveoli. The passageways are not just rigid tubes. The diameter of each one can be adjusted by smooth muscle fibers in its wall. The autonomic nervous system controls this smooth muscle. |
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Bronchioles |
After it enters the lung, each main bronchus divides into smaller bronchi, which divide into even smaller bronchi and finally into tiny bronchioles. |
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Alveolar ducts |
The bronchioles continue to subdivide down to the smallest air passageways - the microscopic alveolar ducts. |
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Alveolar sacs |
The alveolar ducts end up in groups of alveoli arranged like bunches of grapes. These groups of alveoli are called alveolar sacs. |
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Bronchodilation |
During times of intense physical activity, the bronchial smooth muscle relaxes, allowing the air passageways to dilate to their full maximum diameters in a process that helps the respiratory effort move the greatest amount of air back and forth to the alveoli with each breath. |
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Bronchoconstriction |
At more relaxed times, fully dilated air passageways would actually create more work for the respiratory muscles to move air through gently. So, at rest, the bronchial smooth muscle partially contracts, reducing the size of the air passageways to a more appropriate size. |
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The Lungs |
The two lungs together form a shape that is somewhat like a cone because of chest cavity. It is light and spongy. Each lungs is described as having a base, and apex. The base of each lung is in the caudal part of the thoracic cavity and lies directly on the cranial surface of the diaphragm. The apex of each lung is much narrower than the base and lies in the cranial portion of the thoracic cavity. |
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Mediastinum |
The area between the lungs is called the mediastinum. |
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How to distinguish lungs? |
The lungs are subdivided into sections called lobes. There are two ways to distinguish the lobes: Cranial, Middle, Caudal 1. By externally visible grooves and clefts 2. By the internal major branches of the bronchi. |
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Hilus |
This is where air, blood, lymph, and nerves enter and leave the lung, and it is the only area of the lung that is "fastened in place". |
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Pulmonary Circulation |
Deoxygenated blood enters lungs thru pulmonary artery. Blood vessels follow and subdivide along with the bronchial tree. Capillary networks around alveoli allow for CO2 and O2 to be exchanged. See pg. 371 |
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The Alveoli |
External respiration takes place in the alveoli, where o2 and co2 are exchanged between the blood and the air. Alveoli are tiny, thin walled sacs that are surrounded by networks of capillaries. Made up of simple squamous epithelial. |
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Surfactant |
Each alveolus aka. alveoli is lined with a thin layer of fluid that contains a substance called surfactant. Surfactant helps reduce the surface tension and friction of the fluids. |
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The thorax aka Thoracic Cavity aka Chest Cavity |
Its main contents include the lungs, heart, Lg blood vessels, nerves, trachea, esophagus, lymphatic vessels, and lymph nodes. |
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The Pleura |
A thin membrane that covers the organs and structures in the thorax and lines the inside of the thoracic cavity. |
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The Mediastinum |
The portion of the thorax between the lungs. It contains the heart and most of the other thoracic structures, including the trachea, esophagus, blood vessels, nerves, and lymphatic structures. |
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The diaphragm |
Is a thin sheet of skeletal muscle that forms the caudal boundary of the thorax and acts as and important respiratory muscle. In its relaxed state, the diaphragm assumes a dome shape with its convex surface facing in a cranial direction. The base of lungs lie on the cranial surface. When the diaphragm contracts, its dome shape flattens out somewhat. This enlarges the volume of the thorax and helps accomplish the process of inspiration |
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Lung Function |
The process of respiration requires effective movement of air into and out of the lungs at an appropriate rate and in a sufficient volume to meet the bodys needs at any particular time. Once fresh air has been drawn into the lungs, oxygen has to be moved into the bloodstream and cO2 must be extracted from it. The old air must then be blown out and the whole process repeated. |
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Negative Intrathoracic Pressure |
There is a partial vacuum within the thorax. That partial vacuum pulls the lungs tightly out against the thoracic wall. Pleura fluid between the lungs and the thoracic wall provide lubrication. The lungs follow passively as movements of the thoracic wall and diaphragm alternately enlarge and diminish the volume of the thorax. This pulls air into lungs (inspiration) and blowing it back out (expiration). Neg. Pressure also helps return blood back to heart. |
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Inspiration aka inhalation |
To draw air into lungs. The enlargement of the volume of the thoracic cavity by the inspiratory muscles. The lungs follow the enlargement passively, and air is drawn into them via respiratory passageways. The main inspiratory muscles are the diaphragm & external intercostal muscles. |
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Expiration aka exhalation |
Process of pushing air out of the lungs. Opposite of inspiration in that the size of the thoracic cavity is decreased. This compresses the lungs and pushes air out through the respiratory passageways. The main expiratory muscles are the internal intercostal muscles and the abdominal muscles. |
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Respiratory Volumes |
The quantity of air involved in respiration can be described with some standardized terms, such as: - Tidal Volume - Minute Volume - Residual Volume |
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Tidal Volume |
Is the volume of air inspired and expired during one breath. (during normal breathing) |
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Minute Volume |
Is the volume of air inspired and expired during 1 minute. |
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Residual Volume |
Is the volume of air remaining in the lungs after maximum expiration. (air in lungs after max. exhale) |
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Exchange of gases |
The basic force behind the exchange is simple diffusion of gas molecules from areas of high concentration to areas of low concentration. - Inspiration: high level of O2 and low CO2 - Expiration: high level of CO2 and low O2 In capillaries, blood contains low O2 and high Co2. When this blood circulate alveoli with High O2 and Low Co2, molecules will diffuse from high level of concentration to low level of concentration. |
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Respiratory Center |
Breathing is controlled by an area in the medulla oblongata of the brain. Directing timing and strength of muscle contraction. Within the respiratory center are individual control centers for functions such as inspiration, expiration, and breath holding. They send nerve impulses out to the respiratory muscles at a subconscious level (automatic). Breathing can be overriden by voluntary control from the conscious mind for brief periods. |
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Mechanical Control for Breathing |
Operates thru stretch receptors in lungs. When the lungs inflate to a certain preset point during inspiration, a nerve impulse is sent indicating the lungs are full. The respiratory center sends out nerve impulses to stop the muscle contraction that have been producing inspiration and start the muscle contraction that will produce expiration. When lungs deflate, another nerve impulse signals lungs are empty. Then another impulse is sent to stop expiration and start process of inspiration. The net effect of the mechanical control system is to maintain a noraml, rhythmic, resting breathing pattern. |
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Acid Base Balance ` |
Respiratory system influences amount of CO2 in the blood. The blood level of Co2 and blood pH are linked. As Co2 level in the blood rises, the pH of the blood goes down, indicating that the blood is becoming more acidic If C.C.S detect a rise in blood Co2 and a decrease in blood pH, it is a signal to increase the rate and depth of respiration to eliminate more Co2 from lungs. If Co2 level falls too low, with a high rise in blood pH, respiration is decreased to allow the Co2 level to rise back in blood. |
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Chemical control for breathing |
Chemical receptors in blood vessels and in the brainstem constantly monitor various physical and chemical characteristics in blood. They monitor it also in carotid artery and aorta for: - Co2 content - the pH levels - O2 content |
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Co2 level |
Co2 variations in the blood vary and lungs must keep it at a homeostasis. If there is an increase of CO2 in blood, then it creases the blood pH. This triggers respiratory center to increase R.R depth. If there is a decrease in Co2 in blood, then blood pH increases. This triggers respiratory center to decrease R.R. depth. |
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Slight Hypoxia |
The effects of variation in the blood O2 level are not as clear cut as the Co2 effects. If a slight decrease in the blood o2 level occurs, the chemical control system signals the respiratory center to increase rate and depth of breathing so that more O2 will be taken in. |
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Severe Hypoxia |
If blood o2 level drops below critical level, the nurons of the Respiratory Center can become so depressed that they cannot send adequate nerve impulses to the respiratory muscles. This can cause breathing to decrease or stop completely. |
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The lymphatic system |
- System of ducts and fluids lymph - System picks up fluid leaked from capillaries - Lymph ducts carry lymph to blood vessels near heart - lymph is put back into blood stream - It removes excess tissue fluid and is separate from the cardiovascular system. |
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Herbivores |
They eat plants. In herbivores such as horses and cattle, the process of converting consumed plant material into usable nutrients nd energy is dependent on microbial fermentation chambers in the GI tract. - Ruminants = cattle, sheep and goats - Non Ruminants = horses |
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Carnivores |
They eat meat. In carnivores such as the cat, the GI tract itself is responsible for converting consumed meals into nutrients nd energy w/ out aid of microbial fermentation chambers. Carnivores have an inconspicuous nd small cecum because microbes plan an insignificant role in breaking down their food. |
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Omnivores |
Eat a combination of plant materials and meat - Humans - pig - dog |
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Ruminants |
Cattle, Sheep and goats are herbivores. They have large microbial fermentation chambers where the plant materials are partially broken down before the food reaches the true stomach. |
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Non ruminant |
Herbivores such as horses are called hindgut fermenters. They have an extremely well developed and expansive fermentation chamber (cecum) at the junction of the small and large intestines that allow microbes to help break down plant materials. |
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Digestion |
Digestion begins inside the G.I tract but, interestingly anything within the G.I tract can be considered still outside the body. Even after they have been broken down into basic parts, the smaller nutrients do not enter into the body until they are absorbed across the intestinal tract wall. |
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Digestion |
Refers to the part of the process in which larger molecules are broken down into their smaller component parts. Only small molecules enter the body. The breakdown process occurs in 2 different ways: - mechanical digestion - chemical digestion |
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Mechanical Digestion |
Refers to the gastrointestinal tract movements , which physically break food up into its smaller parts. |
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Chemical Digestion |
A chemical reaction breaks the bonds holding macromolecules together, resulting in the production of smaller molecules. |
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Basic structure of the G.I tract |
The gastrointestinal tract runs from the oral cavity to the anus and includes: Oral cavity, esophagus, stomach, small intestine, Lg intestine. |
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Gastric |
When referring to the stomach |
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Enteric |
When referring to the intestines |
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G.I tract layers |
Most of the GI tract wall consists of four layers of tissue from the lumen (inside space) outward: - Mucosa (Inner) - Submucosa - Muscular layers ( Inner Circular & Outer longitudinal) - Serosa (Outer) |
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Epithelial tissue of mouth and anus? |
Stratified Squamous Epithelium |
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GI tract epithelium |
Simple columnar epithelium connected by tight junctions |
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Skeletal muscle in GI |
- Oral Cavity - Pharynx - Esophagus (some species) - External Anal Sphincter |
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Oral Cavity aka Mouth aka Buccal Cavity |
It is the entrance to the G.I. tract; the mouth. It contains the teeth, tongue, and everything else required to ingest food. Oral cavity consists of 2 parts: 1. Vestibule 2. Oral Cavity |
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Vestibule |
Is the space between the outer surface of the teeth and the surrounding lips and cheeks. - betwen lips, cheek and outside teeth |
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Oral Cavity |
The space bordered by the inner surface of the teeth laterally and rostrally and by the hard and soft palate. - Inside of teeth, hard and soft palates. |
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Prehension |
Maneuverable lips that assist animals in the process of bringing food into the oral cavity. |
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Teeth |
The teeth are embedded in the upper maxilla bone and lower mandible bone. |
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Alveoli (Cavity) |
Teeth are found in sockets or cavities called alveoli and are held in place by the periodontal ligament. |
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Parts of tooth |
- Crown = part of the tooth that projects above the gingiva (gums) - Root = embedded in the alveoli below the gingiva (gums) - Apex = The tip of the root of a tooth where blood vessels and nerves enter the tooth - Neck = Area where the crown and the root meet (right on the gums) |
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Tooth Structure |
- Crown = is covered by a thin layer of white hard material called enamel - Dentin = under the enamel is the dentin. Dentin forms the bulk of the tooth and is hard as bone. - Pulp Cavity = Dentin surrounds an inner area called pulp cavity that contains blood supply and nerves which supply the tooth. - Cementum = thin bonelike covering over the roots of brachyodont teeth |
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Brachyodont teeth |
Carnivores, humans and pigs have teeth classified as brachyodont teeth. They have small crowns and well developed roots. - Ruminant incisors are also brachyodont teeth. - These teeth do not continually grow because the apices of their roots are open for only a finite period of time. |
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Hypsodont Teeth |
- A horses incisors and cheek teeth, boars canine teeth, ruminant cheek teeth and some of the teeth of rodents and lagomorphs classified as hypsodont teeth. - Teeth grow continuously during life of animal because of large reserve of crown beneath the gingiva (gums) |
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Deciduous Teeth aka Baby Teeth |
All domestic species have two sets of teeth: 1. Deciduous dentition 2. Permanent dentition (adult teeth) |
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Deciduous dentition aka milk teeth/ baby teeth |
They tend to be smaller and whiter. They are present in the jaw at birth, but erupt through the gums at different times in diff. species. |
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Heterodont Dentition |
Refers to teeth of differing shapes and sizes. Domestic animals have heterodont teeth. There are four diff. types of teeth nd each has a diff. function: - Incisors = Found in premaxilla or incisive bone. Small and used to cut and nibble on food. - Canine = Found in the macilla and mandible. They are sharp and pointed used to tear flesh and hold prey - Premolars = Found in the maxilla and mandible. Act like shears, cutting and slicing meat from bones and grind food into small pieces. - Molars = Only found in adult teeth also grind and shred food. |
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Dental Formula |
Represents typical number for each type of tooth found on one side of the upper and lower jaws. - Indicates how many of each type of tooth are present |
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The tounge |
- Extrinsic muscles anchor it in place - Intrinsic muscles make up the tounge - Exterior of tongue is stratified squamous epithelium. - On the dorsal surface the tongue has papilla. Some papillae have a mechanical function and assist in grooming and moving food bolus down the pharynx. Specialized papillae contain taste buds, has a nerve supply, which allows sensation of pain, temperature and touch. The tongue has blood which make thermoregulation through panting. |
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Salivary Glands |
They deposit saliva into the oral cavity via ducts. It is composed mainly of water but also contains proteins, electrolytes, antibodies, salivary bicarbonate and enzymes. Saliva production varies depending on species and diet. (Herbivores the most) |
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Lysozyme |
An enzyme found in the saliva, along with immunoglobulins, helps control the bacterial population in the oral cavity. |
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Amylase |
Some species, mainly omnivores, as well as some avian species, have the starch digesting enzyme amylase in their saliva. Amylase assists in the breakdown of starchy carbohydrates. |
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Saliva Function |
It lubricates, has antibacterial action, pH regulation, thermoregulation, and enzymatic digestion. Glands are paired and located near the oral cavity. There are 3 main salivary glands: - Parotid - Mandibular - Sublingual Depending on gland, the secretion can be watery, mucous, or mixed. |
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Temporomandibular Joint T.M.J. |
- It forms the connection between the condylar process of the mandible (lower jaw) and the cranium. - The movements allowed by the TMJ include extension, flexion and translation. The movement of the mandible to the side and forward is called translation. Diet influences how much translation can occur. (Chewing) (Rotates jaw to grind) |
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The Esophagus |
It is a muscular tube that connects the pharynx to the stomach. It is lined by mucosa to allow expansion or dilation when food passes through it. The tunica muscularis consist of 2 layers of muscle, the inner circular layer and the outer longitudinal layer. Both muscle layers are needed to move food down the esophagus. |
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Cardiac Sphicter |
There is a thickening at the gastric end of the esophagus/ beginning of the stomach called the cardiac sphincter that functions to prevent the highly acidic content of the stomach from backflowing or refluxing into the esophagus. |
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Hiatus |
Hole in diaphragm, weak spot |
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Peristalsis |
The pattern of muscle contraction, involving the circular muscle layer in the esophagus to propel food through the G.I. tract. |
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Bolus |
Once the food is sufficiently macerated and mixed with saliva it forms a bolus that must now be transported. |
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Stomach Functions |
The function of the stomach are the storage of ingested food, mechanical and chemical breakdown of food, and production of intrinsic factor, which is required for vitamin b12 absorption in small intestines. |
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Chyme |
When the food is in a semiliquid state it leaves the stomach and enters the duodenum, where it is called chyme. |
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Monogastric stomach |
Monogastric animals, including the dog, cat, and horse have a single or simple stomach with one chamber. It is C shaped located behind the diaphragm in the left. |
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Ruminant Stomach |
Ruminant such as cows, goats, and sheep, have a complex stomach consisting of four chambers. |
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Rugae |
Rugae are transient folds of gastric mucosa, which allow the stomach to expand when it is filled with food and increase the surface area for absorption. Rugae flatten out when stomach is full. |
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Gastric mucosa |
made up of simple columnar epithelium and produce mucous that helps protect the stomach from the acidity of the gastric secretion. |
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Glandular portion (proximal portion) |
The glandular portion of the stomach can be divided into 3 basic regions: - Cardia - Fundus = rugae are prominent so the fundus can expand to store food - body largest section of the stomach |
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Gastric Pits |
In all 3 glandular regions gastric pits or shallow depressions dot the mucosal surface of the stomach. The gastric pits are the openings of ducts that are lined by glandular cells. The type of glandular cell depends on the region of the stomach and each secrete different substances. |
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Gastric Secretion |
Gastric Mucosa - Mucus: Mucous cells - HCI (hydrochloric acid), instrinsic factor: Parietal Cells - Pepsinogen: Chief cells - enzymes - Digest Protein |
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Pepsinogen > pepsin |
Pepsinogen is an inactive precursor form of the enzyme pepsin. It is converted into pepsin by the acidic environment of the stomach created by HCI. Pepsin enzyme begin chemical digestion of proteins. Once pepsinogen is activated to pepsin it can also activate other pepsinogen molecules. |
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Pyloric Antrum |
Distal portion of stomach = more muscular The area continuous with the body of the stomach. The stomach narrows into the pyloric canal terminating at the pylorus, which opens into the duodenum through a circular muscle called the pyloric sphincter. |
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Ruminant Stomach |
The ruminant stomach consists of four chambers, one stomach. The first 3 chambers are known as the forestomach or forestomachs: non glandular 1. Reticulum = non glandular 2. Rumen = non glandular 3. Omasum = non glandular The last chamber or the true stomach is abomasum. (glandular ) like monogastric stomach |
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Ruminants |
Ruminants are herbivores. To digest properly ruminants require a more complex and involved digestion process. |
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Forestomachs |
The rumen is on the left side. Each forestomach performs a diff digestive function. Rumen is Lg and flexible where fermentation occurs. Contains many microorganisms that assist in breaking down the carbohydrates. They are lined by stratified squamous epithelial and are non glandular. |
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Papillae |
The ruminal mucosa contains numerous papillae, which help to increase the surface area available for absorption |
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Pillars |
Pillars (muscular folds) divide the rumen into the dorsal sac, ventral sac, and 2 caudal sacs and increase surface area |
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Reticulum aka The Honeycomb |
Because its mucosa resembles a honeycomb, with its crisscross pattern. It is located cranial to the rumen. |
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Reticulorumen |
The reticulum and the rumen are indeed reffered to as one unit |
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Esophageal Groove |
Links esophagus with the omasum and plays a critical role in the young ruminant. The groove folds in and essentially turns into a tube for milk to travel directly into the omasum and abomasum, bypassing the reticulum and rumen. It also prevents milk fermentation |
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Omasum chamber aka book stomach |
Because of its many leaves, which resemble like pages in a book. The leaves are folds of mucosa that have many papillae on their surfaces. This increases the absoptive surface area, where absorption of water, salt, bicarbs take place. It connects reticulorumen to the abmasum. |
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The Abomasum aka True stomach |
it is lined with glandular tissue located on the right side of the abdomen. Functions like the simple stomach in the monogastric animal. |
