ANSCI 3300 Lecture 2nd Term PDF

**ANSCI 3300 LECTURE 2^nd^ TERM** **The Cardiovascular System** **Components of the cardiovascular system** the blood vascular system is made up of four parts: 1\. Blood which is a fluid connective tissue that transports oxygen and nutrients around the body and collects waste products produced b...

**ANSCI 3300 LECTURE 2^nd^ TERM** **The Cardiovascular System** **Components of the cardiovascular system** the blood vascular system is made up of four parts: 1\. Blood which is a fluid connective tissue that transports oxygen and nutrients around the body and collects waste products produced by the tissues. 2\. The heart which is a hollow, muscular, four-chambered organ responsible for pumping blood around the body. 3\. The circulatory system is a network of arteries, veins and capillaries in which the blood flows around the body. 4\. The lymphatic system is a network of lymphatic vessels that transports lymph or excess tissue fluid around the body and is responsible for returning it to the circulation. **B. The Blood 1. Functions of the blood** 1\. Distribution of nutrients absorbed from the digestive tract 2\. Transport of oxygen from the lungs to cells throughout the body 3\. Transport of carbon dioxide from metabolizing cells to the lungs 4\. Transport of waste products from metabolizing cells to the kidneys for excretion 5\. Transport of hormones from endocrine glands to target cells 6\. Assistance in body temperature control by transporting heat from deeper structures to the surface of the body 7\. Assistance in maintaining a constant pH of body fluids by providing chemical buffers 8\. Assistance with the prevention of excessive loss of blood from injuries by providing proteins and other factors necessary for blood coagulation 9\. Assistance with the defense of the body against disease by providing antibodies, cells, and other factors of body defense. **2. Components of the Blood** Blood makes up about 7% of the total body weight and has a pH of about 7.4 (7.35--7.45). Blood is sticky and viscous having about five times the viscosity of water with specific gravity of 1/20 more than water (1.06). The color ranges from bright red (oxygenated) to dark red (unoxygenated). It is composed of two parts, the cellular elements and the fluid elements. a. **Cellular elements of blood** The **erythrocytes (red blood cells)** are non-nucleated biconcave disc cells that specialized in the transportation of oxygen. It contains hemoglobin (principal oxygen transport medium of blood and responsible for its red color). These cells are involved in transporting oxygen to tissues, transporting carbon dioxide to the lungs and maintaining cell shape and deformability. The second cellular components of blood are **leucocytes (white blood cells).** These are nucleated cells capable of independent movement. These can be grouped either as granulocytes, those that contain granules within the cytoplasm or agranulocytes, absence of the granules. The agranulocytes include the **monocytes,** the largest white blood cells which are involved in phagocytosis and the lymphocytes which produce antibodies, neutralize or fix toxins and aid in fat resorption from the intestine. The third cellular components are the **thrombocytes (platelets),** these cells are non-nucleated, round to oval in shape with clear cytoplasm that contains small blue to purple granules. The granules contain clotting factors and calcium, which are necessary for blood to clot. smallest of the formed elements and necessary for blood clotting. The **plasma** is the straw-colored fluid component of an uncoagulated blood while serum is the fluid component after the blood has clotted. Essentially, serum is plasma minus the plasma proteins responsible for producing the clot Plasma is about 92% water and 8% other substances. Globulin, albumin, and fibrinogen are the primary plasma proteins. Globulin and albumin are important in the immune responses of the body. Fibrinogen is important in the process of blood clotting. Plasma also contains small amounts of ions, gases, hormones and nutrient substances. The **heart is a cone-shaped** hollow muscular organ. It is partially surrounded by a serous sac **called pericardium or pericardial sac.** The layers of the heart are composed of an outer serous covering(epicardium), an inner endothelial lining (endocardium) and a thick muscular layer. 1. **Blood Circulation** To start the circulation of blood through the heart, let's start in the **vena cava**, the large vein that brings deoxygenated blood from the systemic circulation (but not the pulmonary circulation) to the heart. The vena cava enters the **right atrium** of the heart. The deoxygenated blood passes from the right atrium through the **tricuspid valve** into the **right ventricle.** At this point the **pulmonary valve** in the right ventricle is closed. When the right ventricle is full the tricuspid valve is forced closed and the pulmonary valve is forced open. The right ventricle contracts and the deoxygenated blood leaves the right ventricle through the pulmonary valve and enters the pulmonary circulation via the **pulmonary artery.** After the deoxygenated blood has been oxygenated in the pulmonary circulation (lungs) it comes back to the heart via the **pulmonary vein** that empties into the left atrium. The mitral valve opens and the blood from the **left atrium** enters the left ventricle. When the ventricle is full the **mitral valve** is forced closed and the aortic valve is forced open. The **left ventricle** contracts and oxygenated blood leaves through the **aortic valve** and enters the systemic circulation via the **aorta,** the largest artery in the body. Once in the systemic circulation the blood is distributed throughout the animal's body through the arteries. 5\. **Blood vessels** The cardiovascular system is composed of three blood vessels: the arteries, veins and capillaries. Arteries carry blood away from the heart. In the pulmonary circulation they carry deoxygenated blood to the lungs for oxygenation. In systemic circulation they carry oxygenated blood throughout the animal's body. There are two types of artery: **elastic arteries and muscular arteries. 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 walls. 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. Best example is the aorta, the largest elastic artery in the body. **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 off the smallest elastic arteries and therefore have a smaller diameter. 6\. The **Pulse rate** The **pulse** is the rate of alternating stretching and recoiling of the elastic fibers in an artery as blood passes through it with each heartbeat. The pulse wave resulting from the stretching and recoiling of the artery travels through all the arteries and arterioles and dissipates in the capillaries. In most animals the pulse is felt on superficial arteries lying against firm surfaces such as bones like the femoral, brachial or coccygeal artery. The pulse and the heartbeat in an animal are not the same thing. The pulse is felt on a superficial artery; the heartbeat is counted using a stethoscope to listen to the animal's chest (auscultation) to hear the heart sounds. 7\. The lymphatic system The lymphatic system is part of the circulatory system of the body and is responsible for returning the excess tissue fluid that has leaked out of the capillaries to the circulating blood. The fluid within the system is called lymph and is similar to plasma but without the larger plasma proteins. However, lymph contains more lymphocytes than are present in the blood. The lymphatic system is composed of both lymphatic vessels and lymphoid tissue, which are found in all regions of the body with a few exceptions such as the central nervous system and bone marrow. The functions of the lymphatic system are a\. To return excess tissue fluid that has leaked out of the capillaries to the circulating blood b\. To remove bacteria and other foreign particles from the lymph in specialised filtering stations known as lymph nodes c\. To produce lymphocytes, which produce antibodies; the lymphatic system may also be considered as part of the immune system d\. To transport the products of fat digestion and the fat-soluble vitamins from the lacteals of the intestinal villi to the circulation. a\. The **lymph nodes** are ovoid, pinkish bodies intercalated in the course of the lymph vessels. These act as filters and phagocytic structures, removing foreign matter from the lymph stream before passing it on through other lymph vessels toward the heart b\. The **thymus** is located in the cranial thorax. It is largest in size when an animal is young, but shrinks and is replaced by fat as the animal matures, making it difficult to locate in adult animals. It is responsible for the production of T lymphocytes that give rise to the cell mediated immune response. c\. The **bursa of Fabricius** is found only in birds and is similar in structure and function to the thymus. It is a round sac that sits right above the cloaca d\. **Peyer's patches** are located in the wall of the small intestine. They have various structures and functions depending on the species. However, their common function is the activation of B cells to produce antibodies against antigens in the small intestines. Peyer's patches are just one type of gut associated lymphoid tissue (GALT) located throughout various areas of intestinal mucosa and submucosa e\. The **spleen** is a tongue-shaped organ located on the left side of the abdomen. It is near the stomach in and near the rumen in ruminants. Not only does the spleen store red blood cells and produce red blood cells during fetal development, but it also filters the blood and lymph. f\. The **tonsils** like those found in the ceca of chickens and in pharynx serve as regional lymph node. **THE RESPIRATORY SYSTEM** Functions of the respiratory system Supplies oxygen to the blood and removes carbon dioxide from the blood Gas exchange between blood and cells at the level of the tissues Assist in the regulation of the acidity of the extracellular fluid of the body Assist in temperature regulation Elimination of water Phonation (voice production) **Structures of the respiratory system:** The external respiratory system is essentially a series of passages and tubes that commence at the exterior of the animal and end blindly in a multitude of tiny, thin-walled, closed sacs **or alveoli**. The structures involved in the system are: the nasal cavity, pharynx, larynx, trachea, bronchi, lungs, pleurae and thoracic cavity a\. **nostrils** (external nares) are the external openings of the respiratory tract b\. **nasal cavity** The nasal cavity is separated from the mouth by the hard and soft palates and separated into two isolated halves by a median nasal septum. It is lined with mucous membrane. The sinuses are outpouchings of the nasal passages that are contained within spaces in certain skull bones. c\. **pharynx** - is a funnel-shaped Musculo membranous organ which is a common passageway for food and air. d**. larynx** - connects the pharynx and the trachea. It supports the epiglottis, which regulates the passage of air and prevents the aspiration of food or other foreign bodies. It also serves as the voice box. e\. **trachea** - is a non-collapsible tube formed by a series of adjacent cartilage rings. It is a passageway to the duct system of the lungs. f**. lungs** - are two elastic membranous sacs whose interior is in free communication with the outside air via a system of passages. The general scheme of the duct system of the lungs is as follows. g**. pleurae** - are serous membrane, which covers the inner wall of the thorax and the thoracic structures. h\. **diaphragm** - is a musculomembranous partition that completely separates the thoracic from the abdominal cavity. It is a muscle for respiration. i**. thoracic cavity** -- surrounds the heart and its structures, lungs and part of the trachea and esophagus, mediastinal structures and the great vessels entering and leaving the heart. It is bounded by: thoracic inlet -- anterior diaphragm -- posterior thoracic vertebrae and muscles -- dorsal ribs, costal cartilage and costal muscles -- lateral sternum, sternal muscles and transverse thoracic muscle -- ventral 4\. Regulation of respiration a\. respiration is regulated by the complex action of the various muscles of respiration Three sets of muscles are responsible for respiration \(1) **Diaphragm** is a dome-shaped muscular structure that forms the boundary between the thoracic and abdominal cavities. When the diaphragm contracts, it flattens and increases the volume of the thoracic cavity. \(2) **External intercostal** **muscles** contract and lift the ribs upwards and outwards, thus increasing the volume of the thoracic cavity. \(3) **Internal intercostal** **muscles** fill the intercostal spaces and lie deep to the external intercostal muscles. During forced expiration they contract in conjunction with the abdominal muscles to force air out of the lungs. b\. **respiratory center** (medulla oblongata and pons) which is influenced by both sensory nerves and chemical changes in the blood and controls the rate and depth of breathing. **Lung volumes and capacities** a\. Tidal Volume (TV) -- the amount of air that moves into the lungs with each inspiration or the amount that moves out with each expiration b\. Inspiratory Reserve Volume (IRV) -- the volume inspired after passive inspiration c\. Expiratory Reserve Volume (ERV) -- the volume expelled by an active expiratory effort after passive expiration d\. Residual Volume (RV) -- the volume of air left in the lungs after maximal expiratory effort e\. Total Lung Capacity (TLC) -- sum of all of the lung volumes (TV, ERV, IRV and RV) f\. Vital Capacity (VC)-- amount of air that can move into or out of the lungs and is the sum of the volumes except RV g\. Inspiratory Capacity (IC) -- is the maximum amount of air that can be inhaled past a normal tidal expiration and it is the sum of the TV and IRV h\. Functional Residual Capacity (FRC) -- amount of air that remains in the lung after a normal tidal expiration and it is the sum of the ERV and RV **Types of breathing/respiration** a\. costal (thoracic) -- involves considerable movement of the ribs b\. abdominal (diaphragmatic) -- diaphragm contraction produces visible movement of the abdomen c\. eupnea -- normal quiet respiration; the diaphragm and external intercostal muscle must contract d\. dyspnea -- difficult breathing e\. apnea -- absence or cessation of respiration f\. hyperpnea -- increase in depth or rate of breathing or both g. polypnea -- rapid shallow breathing. **THE STRUCTURES OF THE DIGESTIVE SYSTEM** 1\. Divisions of the alimentary canal **a) Mouth/Oral cavity/Buccal cavity** This is the beginning of the digestive system. This includes the lips, tongue, teeth and salivary glands. \(1) To pick up the food (prehension) and involves the use of the lips and tongue (2) To break up the food into small boluses to aid swallowing (mastication or chewing) and involves the use of the tongue, cheeks and teeth (3) Lubrication of the food with mucus and saliva making it easier to swallow (4) In omnivores (eat both meat and plants) and herbivores (eat only plants), digestion of carbohydrates begins in the mouth with the secretion of salivary enzymes. (a**) tongue** -- consists of a mass of muscle covered by mucous membrane; located on the dorsal surface of the tongue are different types of papilla that assist in the grooming process and in moving the food bolus down into the pharynx; some papillae contain taste buds (b**) lips** -- prehensile organ of sheep, goats and horse \(c) **cheeks** -- musculature structures covered with skin and lined with mucous membrane and aid the tongue in positioning food between the teeth for chewing \(d) **hard palate** -- forms the roof of the mouth and is continued caudally by the soft palate which separates the mouth from the pharynx \(e) **salivary glands -** These are paired glands lying around the area of the oral cavity producing secretions, known as saliva. Saliva has many functions including lubrication, antibacterial action, pH regulation, thermoregulation, and enzymatic digestion (amylase). **(f) teeth** -- embedded in the upper maxilla bone and lower mandible bone. Teeth are important in assisting the animal with the mechanical breakdown of food. Maybe classified according to permanence, according to manner of growth and according to function. a\) According to permanence: ** temporary or milk teeth** -- present at birth or shortly afterwards and persist from a few weeks to several years **adult or permanent teeth** -- replace the milk teeth and usually persist throughout the life of the animal. b\) According to manner of growth ** true teeth (brachyodont**) -- occurs in carnivores, omnivores and in the incisors of ruminants. They possess a crown, neck, and root, grow to adult size and then wear away without further growth **constantly growing teeth** (hypsodont) -- these teeth continue to grow throughout the life of the animal and do not possess a definite root or neck e.g. tusks of swine and incisors of rodents ** constantly erupting teeth** - these teeth possess extremely long roots and no definite neck e.g. entire dentition of equines and the cheek teeth of ruminants c) According to function and diet ** cutting teeth** (incisors) - found in the premaxilla or incisive bone. They are small and are often used to cut and nibble on food. **tearing or seizing teeth** (canines) - located in the maxilla bone and the mandible. They are single teeth on each side of the jaw caudal to the incisors. These teeth are sharp and pointed and are used to tear flesh and hold prey. ** grinding or shearing (premolars and molars**) - cheek teeth and are also found in the maxilla bone and the mandible. The premolars act like shears, cutting and slicing meat from bones and grinding the food into smaller pieces. A tooth is composed of five parts and four tissues. This applies to true teeth. **a) Crown of** the is that part which protrudes above the gum line b\) **Neck** is that part which is found at the gum line. It appears as a constriction, which separates the crown from the root. c**) Root** is that part which is embedded in the tooth socket (alveolus) in the jaw. d\) **Pulp** cavity is a central cavity found in the tooth. It contains the dental pulp, vessels, and nerves e\) **Table surface** is the cutting (incisor), piercing (canine) or grinding (premolar and molar) surface of a tooth The tissues of a tooth ranging from hardest to softest are: enamel, cement, dentine and pulp. a\) **Enamel** is the hardest tissue in the body and usually found as a layer covering the dentine of a tooth. It is generally translucent white to ivory in color. b\) **Cement** is the outermost covering of a tooth, may range from yellow to black in color. In true teeth, it covers the roots only c**) Dentine forms** the bulk of most teeth, covers the pulp and is hard and yellowish-white in color. d\) **Pulp** is a soft gelatinous tissue in the center of the tooth that supports blood vessels and nerves. b\) **Pharynx** -- is a funnel-shaped musculomembranous organ which is a common passageway for food and air. The pharynx can be divided into nasal **(nasopharynx**), oral **(oropharynx)**, and laryngeal (**laryngopharynx)** portions. The muscles of the walls of the pharynx are responsible for the orderly directing of air, food, and liquids in such a way that air from the nasal cavity is directed into the larynx and food and liquids are directed into the esophagus. **The epiglottis** is the part of the laryngeal cartilage that covers the glottis during the act of swallowing, thus preventing the food from being aspirated into the trachea. c**) Esophagus** -- is a muscular tube extending from the pharynx to the stomach just caudal to the diaphragm. From the pharynx, the esophagus runs dorsal to the trachea and usually inclines somewhat to the left in the neck in the midcervical region. It enters the thorax through the diaphragm at the esophageal hiatus. Within the abdominal cavity, the esophagus joins the stomach. d) **Stomach** (1) simple stomach -- located just behind the left side of the diaphragm.The simple stomach is grossly subdivided into the cardia (entrance), fundus, body, and pyloric region (outflow); the pyloric region features a dense, palpable sphincter muscle called the pylorus that controls gastric emptying into more distal parts of the digestive tract. The esophagus joins the stomach at the cardia. The cardia and pylorus are quite close together, giving the stomach a J shape. The body of the stomach is the expansile part and determined largely by the degree of filling. The pyloric region has a very strong sphincter, the pylorus regulates the outflow of the stomach in this region. It contains parietal cells that produce the hydrochloric acid and chief cells that produce pepsinogen. \(2) **compound stomach** -- this is composed of the rumen, reticulum, omasum and abomasum (collectively known as the forestomach) (**a) rumen (paunch**) -- occupies most of the left side of the abdominal cavity and extends from the diaphragm to the pelvis when it is full. It is the largest part of the adult compound stomach and it serves as a fermentation vat, organ of maceration, site of bacterial digestion and organ of absorption \(b) **reticulum (honeycomb**) -- smallest and most anterior section of the compound stomach and it receives heavy matter in food and act as a liquid reservoir to soften these materials. The reticular or esophageal groove links the esophagus with the omasum and plays a crucial role in the young ruminant. This serves as a bypass for milk to travel directly into the omasum and abomasum. **(c) omasum (manyplies; book stomach**) -- spherical organ filled with muscular laminae and this grind roughage before it enters the abomasum \(d) **abomasum (true stomach**) -- is the first glandular portion of the ruminant digestive system that secretes gastric enzymes and hydrochloric acid; in young ruminants, this secretes the enzyme rennin that causes milk protein coagulation. e\) **Small intestine** It is a tube connecting the stomach to the cecum and large intestine. It is suspended from the dorsal part of the abdominal cavity by a fold of peritoneum called the great mesentery. It consists of three parts: \(1) **duodenum** -- fixed part of the intestine and closely attached to the stomach and contains the pancreas \(2) **jejunum** -- about 90% of the total length of the small intestine and together with the ileum forms the mesenteric part of the intestine (3)**ileum** -- last part of the small intestine There are three kinds of glands in the small intestine: (1)**intestinal** glands (crypts of Liberkuhn) -- secrete the enzyme enterokinase and amylase \(2) duodenal glands (Brunner's gland) - secrete mucus \(3) Peyer's patches f**) Large intestine** It extends from the termination of the ileum to the anus. It is composed of the cecum,colon and rectum (**1) cecum --** it is a blind diverticulum at the beginning of the colon. It varies from being small and inconspicuous in the carnivore, where little fermentation is required, to a voluminous and expansive cecum in equine. species that rely heavily on hindgut microbial fermentation. In the horse, the comma-shaped cecum is so expansive that it takes up a large portion of the abdomen on the right side of the animal. It consists of a base, the main body, and an apex. **(2) colon** -- larger than the small intestine, sacculated and has longitudinal bands and in more fixed position (3) **Rectum** -- terminated part of the intestine and act as organ of storage. **g. Anus** -- terminal part of the alimentary system h. Peritoneum -- serous membrane, which covers the abdominal viscera **i. Mesenteries** - double fold of peritoneum that supports the intestine and attaches it to the dorsal abdominal wall j. **Omentum** -- fold of peritoneum that passes from the stomach to the adjacent viscera and also called the "nature's surgical dressing" k**. Ligaments** -- folds of peritoneum, which connect abdominal organs with each other or with the parietal peritoneum of the body wall 2\. Accessory glands of the alimentary system: a\) pancreas -- is a pale pink, lobular gland lying in the first loop of the duodenum and produce sodium bicarbonate and digestive enzymes **b) liver** -- located near the stomach, immediately caudal to the diaphragm; largest gland in the body and functions for storage and formation of glycogen, secretion of bile, detoxification of poisons, breakdown of uric acid, formation of urea and desaturation of fatty acids. **c) gall bladder** -- functions as storage place for bile and it is absent in horse **d) salivary glands** **1) parotid gland** -- it is serous gland that is, it secretes watery clear fluid 2**) mandibular gland** -- mixed gland which produces both mucous and serous fluid **3) sublingual gland** -- mixed gland. Digestive system of fowl **The beak or bill** forms the beginning of the digestive system. The beak opens directly into the mouth and it is used for prehension. In virtually all birds, there are no cheeks as there are in mammals. The tongue is hard and relatively inflexible. The **pharynx** is open dorsally and communicates with the posterior nares via the choanal space. The esophagus is a musculomembranous tube that dilates near the thoracic inlet to form the crop. The crop is not found in all birds. In the chicken, it is located to the right of the median plane and is a single pouch. Its main function is to store, lubricate, and regulate the passage of food. Posterior to the **crop** is the stomach. It is divided into two parts: the anterior thin-walled, spindle-shaped glandular stomach **(proventriculus)** and the posteior, thick-walled, muscular, keratin-lined muscular stomach (**ventriculus or gizzard**). The glandular stomach produces enzymes and hydrochloric acid. The small intestine does not differ in function and structure as in mammals except that the Peyer's patches are absent in birds and the duodenum does not contain Brunner's glands. The ileum lies parallel to the duodenal loops and terminates at the cecal openings. For practical purposes, there is no colon. In most birds there are two **cecae.** The ceca act as a terminal digestive and digestive and water absorption structure and contained scattered follicle of lymphoid tissue (cecal tonsils). The rectum is short and straight and expands rapidly to form the **cloaca.** The cloaca is divided into three segments -- coprodeum, urodeum and proctodeum -- by annular folds.