Physiology Verbal Exam - PDF

Estrus Follicle has grown, increasing the estrogen level in blood. The high level of estrogen stops the release of folliberins and FSH, stimulates the release of follstatins and LH (induces ovulation). Before the rupture of follicle the level of estrogens is the highest, this caus...

Estrus Follicle has grown, increasing the estrogen level in blood. The high level of estrogen stops the release of folliberins and FSH, stimulates the release of follstatins and LH (induces ovulation). Before the rupture of follicle the level of estrogens is the highest, this causes estrus (in most animal species but in some species, e.g., cats, ferrets breeding (coitus) is needed to induce ovulation). Then the level of estrogens rapidly decreases (no follicle) and also follstatins inhibit the development of new follicles. Estrogens When the mature follicle (Graafian follicle) has formed in the ovaries, its fluid contain a lot of the hormone estrogen. Estrogens with the blood are carried throughout the body, reaching certain concentration, it causes an estrus. Effects of estrogen: ○ Stimulates follicular growth ○ Participates in the regulation of LH and FSH release ○ Initiates sexual receptivity ○ Prepares genitalia for copulation and transportation of spermatozoa (blood vessels in the vagina and uterus expand, increases the blood supply, hyperemia appears, the uterus stretches, becomes longer, uterine muscle contractions will intensify, the cervical muscles relax, the cervix of the uterus is filled with transparent, viscous mucus that gradually comes out through the vagina) ○ Creates favourable conditions for fetal development ○ Contributes to growth and development of mammary glands ○ Triggers the onset of parturition ○ Promotes development of secondary sex characteristics 36. What phases can be distinguished during the cardiac cycle? How/in what direction does the blood flow during each phase? The cardiac cycle and its phases The cardiac cycle is a rhythmic, coordinated contraction and relaxation of individual parts of the heart. The entire cardiac cycle lasts: For humans 0.8 sec For a horse approx. 1.4 sec There are 3 phases in the cardiac cycle: Atrial systole (approx. 0,1 sec (in human)) Ventricular systole (approx. 0,3 sec) Total diastole or pause (0,4 sec) 1. Ventricular filling (mid-to-late diastole) 1.1. Ventricular filling At the beginning of the cardiac cycle, both the atria and ventricles are relaxed (diastole). Blood is flowing into the right atrium from the superior and inferior venae cavae and the coronary sinus. Blood flows into the left atrium from the four pulmonary veins. The two atrioventricular valves, the tricuspid and mitral valves, are open, blood flows from the atria into the ventricles. Approximately 70–80% of ventricular filling occurs during this phase.  The two semilunar valves, the pulmonary and aortic valves, are closed, preventing backflow of blood into the right and left ventricles from the pulmonary trunk on the right and the aorta on the left. 1. Ventricular filling (mid-to-late diastole) 1.2. Atrial contraction As the atrial muscles contract from the superior portion of the atria toward the atrioventricular septum Pressure rises within the atria and blood is pumped into the ventricles through the open atrioventricular (tricuspid, and mitral or bicuspid) valves. At the start of atrial systole, the ventricles are normally filled with ~70–80% of their capacity due to inflow during diastole. Atrial contraction contributes the remaining 20–30% of filling. Atrial systole ends prior to ventricular systole, as the atrial muscle returns to diastole. 2. Ventricular Systole 2.1. Isovolumetric contraction (atria in diastole) Initially, as the muscles in the ventricle contract, the pressure of the blood within the chamber rises, but it is not yet high enough to open the semilunar (pulmonary and aortic) valves and be ejected from the heart. However, blood pressure quickly rises above that of the atria that are now relaxed and in diastole. This increase in pressure causes blood to flow back toward the atria, closing the tricuspid and mitral valves. Since blood is not being ejected from the ventricles at this early stage, the volume of blood within the chamber remains constant. This initial phase of the ventricular systole is known as isovolumetric contraction. 2. Ventricular Systole 2.2. Ventricular ejection phase (atria in diastole) In the second phase of ventricular systole, the ventricular ejection phase The contraction of the ventricular muscle has raised the pressure within the ventricle to the point that it is greater than the pressures in the pulmonary trunk and the aorta. Blood is pumped from the heart, pushing open the pulmonary and aortic semilunar valves. Pressure generated by the left ventricle will be appreciably greater than the pressure generated by the right ventricle, since the existing pressure in the aorta will be so much higher. Nevertheless, both ventricles pump the same amount of blood. 3. Early Diastole (isovolumetric relaxation) Ventricular relaxation, or diastole, is divided into two distinct phases. During the early phase of ventricular diastole, as the ventricular muscle relaxes, pressure on the remaining blood within the ventricle begins to fall. When pressure within the ventricles drops below pressure in both the pulmonary trunk and aorta, blood flows back toward the heart. The semilunar valves close to prevent backflow into the heart. Since the atrioventricular valves remain closed at this point, there is no change in the volume of blood in the ventricle, so the early phase of ventricular diastole is called the isovolumetric ventricular relaxation phase. 3./1. Late diastole In the second phase of ventricular diastole, called late ventricular diastole As the ventricular muscle relaxes, pressure on the blood within the ventricles drops even further. Eventually, it drops below the pressure in the atria. Blood flows from the atria into the ventricles, pushing open the tricuspid and mitral valves. As pressure drops within the ventricles, blood flows from the major veins into the relaxed atria and from there into the ventricles. Both chambers are in diastole, the atrioventricular valves are open, and the semilunar valves remain closed. The cardiac cycle is complete. 19. Ticket 37. Describe the process of a normal expiration Expiration is a passive process which is impacted by: 1. Relaxation of the respiratory muscles. 2. Lung elastic powers. 3. Gravity of the chest cavity. 4. Organs of the abdominal cavity that press on the diaphragm after inspiration trying to go back to the previous position. As a result of all these processes, the capacity of the chest cavity reduces. Pressure in the chest cavity becomes less negative.  Lungs follow pressure changes and movements of the chest cavity. Lungs flatten, pressure in lungs becomes higher than atmospheric pressure, therefore air flows out until pressure with the external environment becomes equal. Self regulation of expiration During inspiration lungs stretch, impulses through the afferent (!!!) parasympathetic n. vagus fibers go to the respiratory center, where the inspiratory neurons are suppressed and they stop to send impulses to the spinal↑atory muscles. Muscles relax, lungs deflate. Happens passive expiration Expiratory neurons in medulla oblongata are being activated (inhibit inspiratory neurons) →Pons in brain switches from inspiration to expiration → Information to spinal cord is not sent → Diaphragm and external muscles of chest relax → Chest deflates, pressure in pleural cavity ↑. Lungs contract, air flows out. 38. What are the physiological roles of the hormones produced by the pancreas? Why hypo- and hyperglycemia is dangerous? Pancreas Exocrine secretion – excretory part (secrete digestive enzymes, target organ – duodenum) Endocrine secretion – incretory part pancreatic islets (islets of Langerhans) which produce: ○ α cells (25% of all cells) - glucagon (↑ glucose level in the blood) ○ β cells (~60% of all cells) - insulin (↓ glucose level in the blood), also amylin (a centrally acting, neuroendocrine hormone synthesized with insulin, it inhibits food intake, delays gastric emptying, and decreases blood glucose level, leading to the reduction of body weight) ○ δ cells (~10%) somatostatin (inhibits the release of glucagon, insulin) ○ PP cells - pancreatic polypeptide (inhibit gastrointestinal movement and pancreatic secretion (exocrine, endocrine), as well as gallbladder contraction). The main target organ of these hormones is the liver. Insulin – absolutely necessary for life-support! Both glucagon and insulin impact metabolism of proteins, carbohydrates and fats. Hormones secreted by the endocrine part of the pancreas Hormone-producing cells are collected in the so-called islets of Langerhans (α, ẞ, , PP). There are 1-2 million of them, 2-3% of the mass of the gland, the diameter is ~0.3 mm. The islets are very well blooded. Blood flows from the venous capillaries to the portal vein. The blood is then carried to the liver, which is one of the main target organs for these hormones. If a small amount of insulin is injected into the body: Blood glucose level decreases – hypoglycemia The permeability of the cell membrane to glucose increases, especially in insulin-dependent tissues (adipose tissue, muscle tissue, because they absolutely need insulin to use glucose) Glycogen synthesis increases in the liver and muscles Protein and fat synthesis increases If insulin is administered in small amounts, but long-term – body weight increases If a large amount of insulin is given:  ○ Blood glucose level can drop rapidly and significantly ○ Hypoglycemic coma may occur rapidly. The animal loses consciousness, because hypoglycemia affects the activity of cells in the cerebral cortex (deficiency of energy). If there is a lack of insulin: The blood glucose level increases. Hyperglycemia occurs. It is not life threatening by itself. If the level of glucose in the blood exceeds the so-called glucose threshold, glucose begins to be excreted in the urine. Glycosuria begins. (The renal threshold for glucose is ~10mmol/l in dogs and ~16mmol/l in cats.) Since glucose is an osmoactive substance, it inhibits the reabsorption of water in the nephron tubules. Consequently, the amount of urine excreted increases (polyuria). The animals show strong thirst (polydipsia). Fat oxidation (degradation) processes in the body stop in the intermediate stage, because insulin is absolutely needed for the use of glucose. Therefore, adipose tissue lack energy to fully break down fatty acids!!! Incompletely oxidized metabolic products (called ketones: beta- hydroxybutyric acid, acetoacetic acid, acetone) accumulate in the body. They change the pH of the blood to the acidic side. Acidosis occurs in the body. These acidic metabolic products irritate the respiratory center; the animal breathes more frequently and deeply. The concentration of CO2 in the blood decreases. If acidosis is severe, a diabetic (hyperglycemic) coma occurs, loss of consciousness, heart rate decreases, death. 20. Ticket 39. Name and describe the four types of hypoxia. Hypoxia – lack of oxygen in tissues 1. Hypoxic hypoxia – decreased pO2 in arterial blood; example, in mountains 3 km above the sea level pO2 in inhaled air and alveoli is just 60 mmHg 2. Anemic hypoxia –pO2 in arterial blood is normal but the amount of hemoglobin is decreased (thereby the transport O2 is decreased). 3. Ischemic (stagnant) hypoxia – arterial blood supply to tissues is impaired, and not enough O2 is delivered, despite pO2 and hemoglobin concentration being normal. E.g., a blood clot blocking a blood vessel. 4. Histotoxic hypoxia – pO2 and transport of O2 is normal, but the tissues are unable to use O2 because due to toxins (for example., carbon monoxide, ozone etc.) (decreased bioavailability of O2) * Hypoxaemia – lack of O2 in blood 40. Describe the neural regulation of the renal functions? Neural regulation influences glomerular filtration rate → filtration processes Sympathetic Kidney blood vessels constrict The blood supply to the kidneys decreases ↓ Filtration processes decrease ↓  Diuresis decreases ↓ Parasympathetic Blood vessels dilate The blood supply to the kidneys increases↑ Filtration processes increase ↑ Diuresis increases ↑ "No hormones in this q but I might also ask about antidiuretic hormone, aldosterone but main thing ^" In case of pain Regulation through the cerebral cortex→ Increases the release of ADH in the hypothalamus → Sympathetic nervous system intensifies → Blood vessels constrict → Decreases ↓ blood supply to the kidneys → Decrease ↓ filtration processes and diuresis → 21. Ticket 41. What cells make up the cardiac conduction system? Do all these cells possess automaticity? Describe the cardiac conduction system. Automaticity is the ability of the heart muscle to contract rhythmically without external stimulation, because the excitation occurs spontaneously in the heart itself. The automaticity can be explaided by the cardiac conduction system of the heart. The cardiac conduction system is the place where excitation originates in the heart and through which it spreads. Under natural conditions, excitation in the heart occurs in the conduction system in only one place – in frog in the sinus node, in mammals – in the sinoatrial node. In mammals the conduction system consists of 5 elements: 1. Sinoatrial node is located in the posterior wall of the right atrium This node generates the action potential (the electrical impulse that initiates contraction) – cardiac pacemaker cells! 2. Atrioventricular node is located in the interatrial septum 3. Bundle of His, 4. Which divides into two bundles – left and right bundle branch 5. They branch into Purkinje fibers, which branch into the myocardium The speed of conduction of excitation in the heart Each part of the heart conducts impulses at a different rate. From the SA node to the left atrium 1 m/sec. In the AV node, conduction speed is the slowest - 0,1 m/sec. This slow conduction in the AV node is called the AV delay. As a result, atrial systole is separated from the ventricular systole. In the bundle of His the fastest 4m/sec  In ventricles, the impulse conduction speed is approximately the same as in atria- 1 m/sec Cardiac conduction system is the place where excitation occurs in the heart and through which it spreads producing sequential, rhythmic electrical activities in the myocardium, followed by a response - systole. Under natural conditions, excitation in the heart occurs in only one place in the conduction system – in frog in the sinus node, in mammals – in sinoatrial node. The bundle of His is the only place where impulse (excitation) can go from the atria to the ventricles, because the atrial muscle is separated from the ventricular muscle by a fibrous connective tissue ring. 42. What are the functions of the digestive tract? Name and describe at least 5. Functions of the digestive tract 1. Secretory function, the glands of the digestive tract secrete digestive juices. 2. Motor function, performs mechanical processing of food. 3. Absorption function. Certain parts of the digestive tract allow water and broken nutrients to enter the bloodstream and lymph through the epithelial cells of the digestive tract. 4. Excretory function. Substances or metabolites that have not been used by the body can be released from the blood into the digestive tract. 5. Incretory function. Hormones produced by endocrine cells in the lining of the digestive tract enter the bloodstream. 6. Receptor function. There are many receptors in the digestive tract, from which many functions are induced (gastric emptying reflex, intestinal peristalsis, secretion of digestive juices, etc.). 22. Ticket 43. What are the physiological effects of progesterone In corpus luteum: is produced the hormone progesterone, which is a pregnancy protection hormone. Progesterone has a local effect mainly on the uterus and mammary glands. By the impact of progesterone: ○ The glands of the uterine mucosa begin to secrete and thus create optimal conditions for the reception of the fertilized ovum ○ Promotes the fixation of the fertilized ovum in the uterus ○ Inhibits the effect of the hormone oxytocin on the smooth muscle of the uterus, ensuring a normal pregnancy ○ Inhibits the development of follicles in the ovaries and the maturation of new ova ○ Promotes the development of mammary gland alveoli. ○ protects pregnancy and stops the growth of new follicles ○ stimulates udder development during pregnancy. Keeps parturition and lactogenesis in check (inhibits effects of cortisol and prolactin)  Progesterone is at high level during pregnancy and after the birth rapidly decreases Prepares the lining of the uterus to receive the fertilized ovum. It lasts for a cow 12-14 days If pregnancy has occurred: Promotes the development of the embryo Delays the development and maturing of new follicles in ovaries. Corpus luteum increases in size and produces progesterone till the second half of pregnancy, when its functions are overtaken by placenta. Then it is called pregnancy corpus luteum. If pregnancy does not occur: corpus luteum is quickly absorbed. As a result, the synthesis of progesterone and its level in the blood decreases in polycyclic animals causing the production of folliberin (follicle‐ stimulating hormone releasing hormone) and then also FSH production. A new follicle (follicles) begins to develop. The cycle begins again. In cows after 12-14 days – corpus luteum disappears almost completely till the next heat. When animals are inseminated it is important to know the beginning of the ovulation. 44. What waves and intervals can be seen on the electrocardiogram? What do they mean? What information we can get by reading ECG? An ECG (electrocardiogram) records the electrical activity of the heart (the potential difference between the excited and non-excited area of the heart during a heartbeat) The ECG can be recorded by placing electrodes in the heart and also on the surface of the body with a special device – an electrocardiograph. A 12-lead ECG is commonly used, but the most widely used are the so-called standard leads from the extremities introduced by Einthoven (marked with Roman numerals I, II and III). The ECG gives information about: The origin of the excitation in the heart. Normal is the so-called sinus rhythm, because the excitation occurs in the SA node. It is possible to judge cardiac arrhythmias. The transmission of excitation in the heart. Basically, about the anatomical, physiological integrity of the cardiac conduction system. Metabolic disorders in the myocardium – blood supply disorders (hypoxia, etc.) Heart pathologies, especially heart attack (myocardial infarction), when a part of the heart muscle is "dead". Occurrence of ECG waves and intervals: P wave: represents depolarization of the atria. Atrial depolarization spreads from the SA node towards the AV node, and from the right atrium to the left atrium. PR interval: is measured from the beginning of the P wave to the beginning of the QRS complex. This interval reflects the time the electrical impulse takes to travel from the sinus node through the AV node. QRS complex: represents the rapid depolarization of the right and left ventricles. The ventricles have a large muscle mass compared to the atria, so the QRS complex usually has a much larger amplitude than the P wave.  ST segment: connects the QRS complex and the T wave; it represents the period when the ventricles are depolarized. T wave: represents the repolarization of the ventricles. Reflects the metabolic processes in the heart. It is the most variable ECG value. The T wave in very old animals and humans can be barely noticeable, but in sport horses the T wave is distinctly large. QT interval: is measured from the beginning of the QRS complex to the end of the T wave. Duration of ventricular depolarization and repolarization. RR interval: duration of the ventricular cardiac cycle (an indicator of the heart rate). 23. Ticket 45. What is spontaneous and induced (reflex) ovulation? Which species are spontaneous and induced ovulators? Types of ovulation 1. Spontaneous ovulation – Ovulation occurs independently of copulation – Cows, sheep, dogs, humans, horses 2. Induced ovulation (reflex ovulation) – Copulation is required for ovulation to occur – Cats, mink, rabbits, camels 46. Motility of the stomach. Transfer of food from the stomach to the duodenum. The speed of gastric emptying. Vomiting, regurgitation. Gastrointestinal (GI) motility is defined as the coordinated contractions and relaxations of the muscles of the GI tract necessary to move contents from the mouth to the anus. Peristalsis is the result of a series of local reflexes. Contraction of intestinal muscle above an intraluminal stimulus associated with simultaneous relaxation of muscle below the stimulus. Starling’s law of the intestine A law stating that a stimulus within the intestine (that is, the presence of food) initiates a band of constriction on the proximal side and relaxation on the distal side and results in a peristaltic wave. When luminal stimulation occurs by mechanoreceptor, chemoreceptor or osmoreceptor activation, there happens a cascade of nerve activation. This results in sequential proximal excitation and distal inhibitory neurotransmission, thus resulting in peristalsis to facilitate gastrointestinal transist. Gastric motility The motility of the forestomachs and stomach is provided by 3 layers of muscles (external - longitudinal; middle - circular; + only in the stomach internal – oblique), which perform mechanical processing of food. Forestomach motility (provided by smooth muscle cells): ○ I contraction system. The contractions of rumen anteroom and reticulum.  ○ II contraction system. The contractions of the dorsal and ventral rumen sacs. Provides food crushing, grinding, mixing with saliva and water. (i.e., stomach groove reflex (!), regurgitation, belching, moving food further). Gastric motility (provided by smooth muscle cells): ○ Tonic movements (typical to empty stomach). ○ Peristaltic or «worm-like» movements (typical to full stomach) Ensure that the food is crushed, mixed with gastric juice until a liquid food porridge is formed. Stomach has receptive relaxation - ability to stretch without high resistance and pressure increase. Receptive relaxation refers to the relaxation of the muscles in the upper portion of the stomach that occurs before the food particles enter the esophagus. This receptive relaxation helps in the movement of the food. This receptive relaxation is achieved with the help of the peristaltic movement of the stomach. Motility of the small intestine Mechanical processing of food Similar to what occurs in the esophagus and stomach, peristalsis is circular waves of smooth muscle contraction that propel food forward. Segmentation sloshes food back and forth in both directions promoting further mixing of the chyme. Almost all components of food are completely broken down to their simplest unit within the small intestine. Instead of proteins, carbohydrates, and lipids, the chyme now consists of amino acids, monosaccharides, and emulsified fatty acids. Two basic patterns of motility: ○ Peristaltic ○ segmental Movements in the small intestine ensure: ○ Mixing of food substances→help digestion, ○ Mixing with digestive juices→help digestion, ○ Pressing of food substances to the intestinal wall, promoting membrane digestion and absorption→help absorption and digestion, ○ Movement of food substances further in the gastrointestinal tract. If the forestomach movements are impaired then all digestive processes are impaired. Basically, forestomach contractions take place in 2 separate systems: 1. Contracts the rumen anteroom and reticulum. 2. Contracts the dorsal sac and the ventral sac is relaxed, so the contents is being pressed into the ventral sac. This is followed by the opposite process of contractions 3. Usually 3 cycles of rumen contractions are observed within 2 minutes. 4. Forestomach motility is regulated by the nerve center in the medulla oblongata. The parasympathetic n.vagus stimulates motility but the sympathetic nerves – reduce it. Forestomach motility is promoted by receptor irritation both in the forestomachs and in various parts of the digestive tract, as well as conditional irritants 5. Forestomach motility also provided rumination (cud-chewing) and belching Evacuation of food from the stomach to the duodenum The periodic opening and closing of the pyloric sphincter is called the pyloric reflex It is initiated by: Feed porridge pH (acidic!) – pH receptors Feed porridge pressure – stretch receptors  Peristaltic waves are stimulated by parasympathetic n.s., inhibited by sympathetic n.s. The portion of food passes into duodenum (1-(3) waves per minute) The pH receptors on the other side of the pyloric sphincter “sense” acidic food portion and close the pyloric sphincter The pyloric sphincter remains closed until the portion of food entering the duodenum is neutralized. What performs this neutralization of the acidity? alkaline pancreatic juice bile duodenal juice Gastric emptying rate It depends on the chemical content and physical properties of food porridge: Stays longer if the food is poorly chewed, very hard, fibrous, dry. Empties faster if the food is warm, liquid, well chewed and mixed with saliva. For example, in horse’s stomach food stays for 6 - 12 hours, but oats leave stomach almost immediatelly after 7-10 minutes. Fatty food stays in the stomach for the longest time Alkaline food leaves stomach faster than acidic. Hypertonic solutions remain in the stomach until they are diluted in gastric juice till the level of an isotonic solution. Gastric peristalsis is promoted by the hormone – motilin, which is secreted by endocrine cells in the pyloric gland zone. Vomiting is a protective reaction of the body that helps to remove useless and harmful substances that have entered the stomach. According to the origin, 2 types of vomiting are distinguished: Vomiting caused by direct irritation of the receptors. These receptors are located in different parts of the body: ○ Root of the tongue, end of the throat. ○ Vestibular apparatus of the ear. ○ Increased irritation of mechanoreceptors and baroreceptors in the gastric mucosa. The effect of substances on chemoreceptors can also cause vomiting (poisons, drugs). ○ Receptors in the gallbladder. ○ Receptors in the renal pelvis (baroreceptors, chemoreceptors). Central vomiting is caused by direct irritation of the vomiting center. Can cause: ○ Mechanical irritants, for example, concussion, increase in the amount of cerebrospinal fluid, production of inflammatory products in meningitis. ○ Chemical irritants- these are various chemicals that directly (humoral) irritate the vomiting center, for example, drugs (apomorphine), increased amount of urea in the body, various bacterial and viral toxins, metabolic products, various changes in physiological conditions – toxicoses (pregnancy). ○ Central vomiting can also be caused by various conditioned reflexes, which occur through the higher cortical and subcortical centers of the brain and are related to previous life experiences (unpleasant smells, visual images, etc.).  Most often dogs, cats, pigs vomit, but ruminants vomit less often. Horses only vomit once in their life, as it is usually fatal. This can be explained by the special location of the stomach and esophagus, so that they cannot physically vomit. Regurgitation is characterized by the passive, retrograde expulsion of previously swallowed material from the esophagus, stomach, or rumen. Most often, regurgitation is perceived as a clinical symptom (e.g., congenital esophageal problems, megaesophagus, rabies, etc.), but can also be associated with a conditioned reflex to feed young. 24. Ticket 47. How does respiration impact heart rate and blood pressure? What is sinus rhythms, sinus arrythmia, tachycardia, bradycardia? What is hypo- and hypertension? Because the composition of gasses in the blood depends on the actions of the circulatory system, then respiratory regulation is mutually coordinated with the regulation of blood circulation and heart rate. Both work together to transport respiratory gasses, oxygenate tissues Respiratory function influences the venous return to the heart, i.e., the respiratory pump – Increased pressure difference between the abdominal and thoracic vena cava during inspiration → enhanced venous return to the heart Pulmonary circulation - all blood leaving the right ventricle of the heart must pass through the lungs! Both systems participate in the regulation of the acid-base balance of the body – Increased CO2 in blood (acidosis) → stimulates breathing → enhanced CO2 removal, normalizing H+ concentration – Vice versa if CO2 is decreased (alkalosis) The respiratory system participates in the regulation of blood pressure via the renin angiotensin-aldosterone system – Angiotensin I is converted to Angiotensin II in the lungs Respiratory-induced fluctuations in blood pressure in the arteries 1. Pulsatory oscillations (first degree waves) are the most common and correspond to the heart rhythm, after ventricular systole pressure increases, after total diastole - decreases; 2. Respiratory fluctuations (second-order waves) correspond to the rhythm of breathing - bp during inspiration decreases (lungs expand, blood accumulates in the veins of the pulmonary circuit, less flows into the left side of the heart), during expiration - bp increases (when the lungs recoil (return to untrenched shape), the blood fills the left heart more) Sinus arrhythmia - normal variation of sinus rhythm - irregularities on ECG Sinus rhythm - normal sinus rhythm Tachycardia - fast heart rate Bradycardia - slow heart rate Hypertension - high blood pressure Hypotension - low blood pressure Respiratory sinus arrhythmia Reflected in the variability of the R-R interval: During expiration R-R prolongs (effect of parasympathetic n.s.) i.e., the heart rate slows down (systolic volume decreases); During inspiration – shortens (effect of sympathetic n.s.), i.e., the heart rate increases (systolic volume increases). In general, although the amount of blood expelled out of the heart during inspiration/expiration (systolic volume) varies, cardiac output remains constant. !!! For newborns (everyone, including humans), dogs (especially small breeds), lasts a lifetime. Cats should not have respiratory sinus arrhythmia! If you notice it, then look for causes outside the heart! 48. Digestion processes in the small intestine? The juice of small intestine, its composition, regulation Intracellular digestion in digestive vacuoles - di- and tri- peptides can be transported to intestinal cells and digested till amino acids. Characteristics of unicellular and lower multicellular organisms. Extracellular digestion in GI cavities; Duodenum, where 3 digestive juices are exposed to food The mucous membrane has a lot of villi + microvilli, → cavity digestion + membranal digestion In each villi, the arterial capillary "enters", but the venous capillary "exits" and the lymph capillary begins blindly, where the splitted products are absorbed. 1. Mechanical processing of food is provided by intestinal smooth muscle, which is regulated by enteric nervous system (ENS) outer Auerbach neural plexus and Cajal cells and autonomic nervous system (ANS). It is crushed (grained), dissolved, mixed with digestive juices and moved forward the digestive tract 2. Chemical In the small intestine, the food is affected by: 1. Pancreatic juice 2. Bile 3. Intestinal juice SMALL INTESTINE JUICE (pH 7.5) Main components: Proteases: proteins till amino acids Enterokinase - trypsinogen into active trypsin  Aminopeptidases – splits amino group Dipeptidases - hydrolyze bound pairs of amino acids, called dipeptides Nucleases - cleave the phosphodiester bonds between the nucleotide subunits of nucleic acids Lipases: fats till glycerin and fatty acids Lipase – splits lipids (main) Amylases: carbohydrates till monosaccharides α-Amylase – starch hydrolyzing Maltase - hydrolyzes maltose to simple sugar glucose Lactase - hydrolysis of the disaccharide lactose into galactose and glucose Sucrase – catalyze the hydrolysis of sucrose to fructose and glucose The lining of the small intestine contains glands that produce intestinal juice (there are 10 000 glands in duodenum per 1cm3 ) The chemical processing of food ends with the intestinal juice. In more further parts of the small intestine, reduces the amount of enzymes and increases the production of mucus. 3. Biological Performs microflor3 and microfauna. ❖ There are 3 main groups of bacteria in the forestomachs: ✓ Cellulolytic bacteria - optimal pH above 6.2 (break down cellulose) ✓ Amylolytic bacteria – pH above 5.4 (break down carbohydrates, starch) ✓ Bacteria that break down nitrogen compounds. ❖ Protozoa catch, digest bacteria and use them in the synthesis of proteins of their own body. Protozoa enter the abomasum in huge quantities and further into small intestine, where they are digested. Central Nervous System (CNS) The CNS influences gastrointestinal function through autonomic pathways. The hypothalamus and brainstem integrate signals related to the gastrointestinal tract and can modulate intestinal secretions. Enteric Nervous System (ENS) The ENS, often referred to as the "second brain" of the gastrointestinal tract, is a highly intricate network of neurons embedded within the walls of the gastrointestinal tract. It operates independently but can be influenced by the CNS. Key Components: 1. Myenteric Plexus (Auerbach's Plexus): Primarily controls gastrointestinal motility but can influence secretion indirectly through interactions with the submucosal plexus. 2. Submucosal Plexus (Meissner's Plexus): Directly regulates enzyme and mucus secretion from the intestinal glands, local blood flow, and electrolyte balance. Autonomic Nervous System (ANS) The ANS modulates the activity of the ENS through parasympathetic and sympathetic inputs: Parasympathetic Nervous System Vagus Nerve: The primary parasympathetic nerve innervating the gastrointestinal tract. It promotes intestinal juice secretion by stimulating the ENS. Sacral Nerves: Also contribute to parasympathetic innervation of the distal colon and rectum. Sympathetic Nervous System  Generally inhibits intestinal juice secretion by reducing blood flow to the gastrointestinal tract and directly inhibiting secretory activity. Mechanisms of Regulation 1. Neural Reflexes: ○ Short Reflexes: These involve sensory neurons in the intestinal wall detecting changes (e.g., distension, chemical composition) and directly stimulating the submucosal plexus to increase secretion. ○ Long Reflexes: These involve sensory neurons sending signals to the CNS, which then modulates the ENS via autonomic pathways. 2. Neurotransmitters and Neuromodulators: ○ Acetylcholine (ACh): Released by parasympathetic fibers and excitatory neurons in the ENS, ACh stimulates the secretion of intestinal juices. ○ Serotonin (5-HT): Released by enterochromaffin cells in response to luminal stimuli, 5-HT can activate local reflexes via the ENS to increase secretion. ○ Vasoactive Intestinal Peptide (VIP): Released by enteric neurons, VIP increases blood flow and stimulates secretion. ○ Nitric Oxide (NO): Acts as a neuromodulator within the ENS, influencing smooth muscle relaxation and potentially modulating secretion.  25. Ticket 49. Why are arteries called the elastic blood vessels? How are arteries divided based on their structure? What is arterial blood pressure, how can we measure it? The walls are able to equalize the blood flow, shrinking and stretching according to the volume of blood (portions), making the flow continuous. Makes the heart work easier - the more elastic the aorta is, the less energy it needs to expel blood. Types of arteries depending on the structure: 1. Elastic type - aorta and pulmonary arteries 2. Muscle type - medium and small arteries (predominant) 3. Mixed type - subclavian artery, etc. (small amount) 50. Motility in small and large intestine. Types of peristaltic waves and their regulation. GI motility is defined as the coordinated contractions and relaxations of the muscles necessary to move contents from the mouth to the anus. Peristalsis is the result of a series of local reflexes Contraction of intestinal muscle above an intraluminal stimulus associated with simultaneous relaxation of muscle below the stimulus 1.Two basic patterns of motility: peristaltic segmental 2. Movements in the small intestine ensure: Mixing of food substances, Mixing with digestive juices, Pressing the food substances to intestinal wall, promoting membrane digestion and absorption, Movement of food substances further in gastrointestinal tract. 1. Movements of large intestine (slower than in small intestine): peristaltic, segmental, antiperistaltic. 2. Movements of large intestine provide: Content mixing with mucus, Pressing the content substances to intestinal walls, promoting water, mineral and other substance reabsorption, Food moving further in gastrointestinal tract, Longer content stay in large intestines, Forming faeces, Defecation. Peristaltic waves are stimulated by parasympathetic n.s., inhibited by sympathetic n.s  26. Ticket 51. What are the functions of capillaries? Describe all the ways substances go through the capillary wall. Blood circulation in capillaries Their wall, one layer of endothelial cells (on the lumen side), on the basal membrane Functions: 1. Circulatory function – the ability to regulate the flow of blood to tissues and organs together with arterioles. 2. Metabolic function – associated with the capillary wall, through which substances move from the blood to the tissue fluid and vice versa - The number of capillaries in different organs depends on their intensity of metabolism, where the metabolism is more intense, in those organs the number of capillaries is higher (heart, liver, kidneys, brain). - The intensity of blood circulation in the capillaries is variable because the capillaries are constantly expanding, narrowing or closing. - Capillaries are closed at rest. In the skin the blood supply to the capillaries can even stop for a short time. Only “on-call” capillaries remain open at rest. As the number of capillaries in the skin increases, the skin temperature rises and the skin becomes pink. - Capillary expansion and opening is caused by metabolic products CO2, histamine, acetylcholine, lactic acid. These substances also increase the permeability of the capillary walls. - Movement of substances through the capillary wall - Substances move in both directions (can be very intense). The movement of substances is determined by the following mechanisms 1. Diffusion - gradient of the concentration of substances form higher concentration to lower. - Passive diffusion– molecules with good diffusion in lipids (happens: more slowly, O2, CO2, medications Affected by: temperature, size of molecules, distance) - Active diffusion- molecules with poor diffusion in lipids pass biological membrane through special channels with help of transfer proteins (happens: faster, specifically affected by concentration of substance, temperature, presence of transfer proteins 2. Osmosis - osmotic pressure (dissolved concentration of salts) gradient divergence between both sides of the biological membrane. Dissolvent (usually H2O) goes through biologic membrane to side with higher concentration of salts 3. Active transport - - Primary active transport - protein works as enzyme (ATP to ATF) and pump (Na+/K+ pump) - Secondary active transport - Na+ transfers with other substance 4. Filtration (F) and reabsorption (R) - F and R depends on hydrostatic (Phydr) and oncotic (Ponc) pressure on both sides of the wall. The Phydr at the arterial end of the capillaries is greater than the Ponc and it promotes filtration Primary active transport - In this mechanism protein (protein transporter) at the same time is: 1. enzyme – it catalyzes hydrolysis of ATF so the gained energy can be used for suction of ions; and 2. pump (carrier) Ex., – in one second it exchanges 200 Na+ from the inside of a cell to 130 K+ to inside of a cell, making the IC space more negative (-)!!! Secondary active transport. It this way Na+ transfer is together with transfer of other substances Ex., Na+ with glucose only if: 1. Na+ is attached with specific transfer protein SGTL-I/-2 and at the same time 2. there is electrochemical gradient of Na+ - it provides the action of Na+/K+ pump, maintaining low level of Na+ in the cell F and R depends on hydrostatic (Phydr) and oncotic (Ponc) pressure on both sides of the wall. The Phydr at the arterial end of the capillaries is greater than the Ponc and it promotes filtration – pushing fluid along with substances though the capillary wall into tissue. At the venous end of the capillaries, the Ponc is greater than the Phydr which promotes reabsorption, and some of the tissue fluid is absorbed back into the capillaries as the blood plasma proteins bind the fluid 52. Secretion of the pancreas. The main components of pancreatic juice. The neural and humoral regulation of pancreatic secretion Glandular Function of the Pancreas Exocrine Function: Synthesizes its enzymes in the inactive form, zymogens, to avoid digesting itself. The enzymes are activated once they reach the small intestine. Secretes bicarbonate ions from the ductal cells to neutralize the acidic chyme that the stomach churns out. The exocrine function of the pancreas is controlled by the hormones gastrin, cholecystokinin, and secretin, which are hormones secreted by stomach and duodenum in response to food. The two major proteases that the pancreas synthesizes are trypsinogen and chymotrypsinogen. These zymogens are inactivated forms of trypsin and chymotrypsin. Endocrine Function: α cells secrete glucagon (increase glucose in blood). β cells secrete insulin (decrease glucose in blood). Delta cells secrete somatostatin (regulates/stops α and β cells). PP cells or gamma cells, secrete pancreatic polypeptide. PANCREATIC JUICE (alkaline reaction!!! - pH 7.8-8.4) In cows is produced 3-7 liters, in humans 0,8. The main organic components are enzymes: Proteases/ zymogens; Trypsinogen → Trypsin, activated by an intestinal juice specific enzyme enterokinase → Splits proteins into peptides and amino acids. Chymotrypsinogen → Chymotrypsin, activated by trypsin. → Breaks down proteins into peptides and amino acids.  Carboxypeptidase – splits carboxyl group from polypeptides Aminopeptidase - splits amino group Lipases: Pancreatic lipases – the main fat breakers Amylases: α amylase – starch → dextrins maltase – maltose → glucose lactase – lactose → galactose, glucose monomers sucrase – sucrose → fructose, glucose Inorganic – Na bicarbonate which “gives” alkaline reaction HUMORAL REGULATION Pancreatic juice: Hormone secretin (↑) Cholecystokinin (pancreozymin) (↑) 3. Secretin: Source: Duodenal epithelium Stimulus for secretion: Acidic chyme entry into the duodenum. Target organ: Stomach, Pancreas and Liver Action: 1. It inhibits the secretion of gastrin in stomach. 2. It stimulates the release of sodium bicarbonate in pancreatic juice from the pancreas. 3. It stimulates liver for the secretion of bile. 4. Regulates water homeostasis in the body. 4. Cholecystokinin (CCK) or Pancreozymin: Source: Duodenal epithelium Stimulus for secretion: Presence of fats, peptides in the duodenum. Target organ: Pancreas and Gall bladder Action: 1. It stimulates the pancreas to release enzymes like amylase, lipase, trypsin etc. in pancreatic juice. 2. It stimulates the release of stored bile from the gall bladder. 3. Inhibits motility 4. Closes pyloric sphincter  27. Ticket 53. Where and how is lymph formed? What provides the circulation of lymph? When blood plasma passes through the wall of capillaries, it fills the gap between the cells, creating tissue fluid. Interstitial fluid to veins and lymph vessels. Lymphatic capillaries are very permeable, so substances and fluid pass quickly from the tissues into the lymphatic capillaries. When tissue fluid enters the lymphatic capillaries, it is already called lymph. There are many lymphocytes in the lymph because there are lymph nodes in the lymphatic pathways through which the lymph flows. Antibody synthesis and phagocytosis occur in the lymph nodes. Lymph has composition of blood plasma, only less protein. Amount of protein depends on the organ → liver higher than leg Lymph has fibrinogen, so it clots. What promotes lymphatic flow? 1. Specific smooth muscle elements (lymphangions) located in the lymphatic vessels that contract regularly. In places where there are no smooth muscles, there are valves that allow lymph flow in one direction – only to large veins. 2. Skeletal muscle contractions 3. Respiratory movements. There is a negative pressure in the chest during inspiration. In large veins, the pressure decreases and the lymph flows in the lower pressure direction. It is as if lymph is being sucked from the lymphatic vessels. Lymph flows into the subclavian vein. The lymphatic system performs: – The tissue drainage – defense function. 54. What are Leydig and Sertoli cells? Where are they found? What are their functions? Sertoli cells Support the developing spermatozoa mechanically Supply nutrients to developing spermatozoa Participate in the regulation of differentiation of spermatogonia into spermatozoa Produce inhibin which inhibits FSH secretion from anterior pituitary gland Leydig cells Located outside seminiferous tubules Produce testosterone – stimulates the production of spermatozoa, male sex characteristics, psychological development and sex drive.  28. Ticket 55. Digestion process in the large intestine (also in the cecum of the horse). Defecation and its regulation. There are no villi in the mucous membrane, except for birds, but there are crypts and many mucous glands. Mucus: Herbivores neutralize volatile fatty acids which were produced during biologic food processing, especially in horses. Forms feces Makes easier to move them out during defecation In the large intestine mainly occurs: water and salt reabsorption. chemical processing of food with «imported» enzymes (at the beginning of the large intestine). The pH of the chyme is important to match the pH when enzymes act! biologic processing of food with the help of the large intestine microflora: - Fermentation processes of undigested and unabsorbed carbohydrates. - Putrefaction processes of undigested and unabsorbed proteins. Synthesis of vitamins (B6, K, biotin, folic acid - PP). Be aware with antibiotic therapy (narrow/broad spectrum???); Protein putrefaction in the large intestine is very rapid due to putrefactive bacteria. A lot of poisonous substances (indole, skatole, phenol, cresol, ammonia) are formed, which are easily absorbed into the blood and enter the liver - they are detoxified to urea, which is excreted in the urine Defecation is a combination of voluntary and involuntary processes that create enough force to remove waste material from the digestive system Fecal masses accumulate at the end of the large intestine, irritate the intestinal stretch receptors and cause relaxation of the internal and external rectal sphincter. The muscles of colon and abdominal muscles contract and feces are being eliminated. The center of regulation of this reflex is located in the sacral segments of the spine, but is partly subordinate to the control of the cerebral cortex 56. What are the functions of the respiratory system? Describe at least 4. 1. Gas exchange (by diffusion – due to the partial pressure difference) 2. Maintain acid-base balance in the body (pH maintenance – blood buffer systems and erythrocytes!) 3. Respiration acts like an excretory system: evaporates H2O, eliminates volatiles: acetone, alcohol, chloroform etc. 4. Respiration takes part in thermoregulation. 5. Enables production of sound. 6. Respiration facilitates venous return to the heart (venous pump) (repeat the impact of respiration on blood pressure). The respiratory system participates in the regulation of blood pressure via the renin angiotensin-aldosterone system 7. Takes part in humoral regulation (repeat: angiotensin II conversion, aldosterone, promotes production of norepinephrine, vasopressin, AKT) 8. Immune protection function 100 m2 barriers with the external environment. How? 9. Analysis of inhaled air (olfactory function), heating the inhaled air, moisturizing and cleaning it Gas exchange happens between the gas and the liquid medium. Before the gas goes from the alveoli to the blood and in other way, it has to go (dissolve) through the lung functional membrane. The higher is the solubility of gases, the faster the gas molecules go from superficial layers to deeper layers, keeping the concentration difference between the gas and liquid → thereby providing faster diffusion. CO2 solubility in lung functional membrane is 20 times bigger than O2 solubility. Thus, CO2 diffuses easier and partial pressure in alveolar air and in blood equalizes faster. RAAS - lungs produce Angiotensin I in blood → ACE → A II → blood vessels constrict → bp increases Aldosterone from adrenal cortex → vasoconstriction, salt and water retension 29. Ticket 57. What is colostrum, its composition? What is its function? Colostrum is a secretion accumulating in the mammary glands before parturition Has a different composition than milk Contains more fat, proteins, minerals and vitamins Lower lactose concentration Contains immunoglobulins – helps protect against infection Ingestion of colostrum increases probability of survival for offspring! High protein concentration – due to high immunoglobulin (antibody) content (IgG, IgM, IgA) Transferred from the mother’s blood to milk In horses, pigs, ruminants – maternal antibodies transferred only through colostrum In dogs, cats and humans – some amount of antibodies transferred the fetus through placenta before parturition In ruminants – colostrum passes directly from the esophagus to abomasum and small intestine Immunogobulins can only be absorbed form the small intestine The small intestine can absorb immunoglobulins best during the first 6h of life Ability to absorb them decreases and then stops in 1-2 days Effects of colostrum Colostrum has a higheramount of nutrients of regular milk Twice the amount of energy 4-5 times the amount of vitamins and minerals Immunoglobulins in colostrum help protect against environmental microorganisms Passive immunity, lasts for 4-6 weeks after birth Immunoglobulins suppress gastrointestinal infections Even after intestinal absorption has stopped Young animals that have not received colostrum: Grow more slowly and not to their full potential Often suffer from diarrhea Critical for young animals in industrial conditions (esp. if hygiene is poor) 58. How happens the insulin release form beta cells into the blood (describe all processes happening in the beta cell)? Insulin Metabolism of glucose, fat, and protein (anabolic) Important effects on carbohydrate, protein and fat metabolism Lowers blood glucose, amino acid and fatty acid concentration in blood Promotes nutrient incorporation into cellular stores The most important anabolic signal in the body! Cellular uptake of glucose (particularly – skeletal muscle, adipose tissue) Not in brain, liver, erythrocytes, renal-, intestinal-, mammary- transport epithelium Stimulation of glycogen synthesis (anabolic effect; storage form of glucose in liver and muscle) Inhibition of gluconeogenesis Cellular uptake of amino acids (particularly – skeletal muscle, liver, adipose tissue) Stimulation of protein synthesis (anabolic effect) Stimulation of triglyceride synthesis (anabolic effect) Inhibition of lipolysis (breakdown of fat) Activity of various intracellular enzymes stimulated (those involved in nutrient metabolism 30. Ticket 59. Types of immunity. Describe each. - Innate (inborn) immune system ´ Mediates the initial rapid response ´ Responds to pathogens even without previous exposure ´ Not specific ´ - Adaptive (acquired) immune system ´ Develops after birth ´ Reacts more slowly ´ More effective ´ Highly specific - Innate: Has two lines of defense ´ Exterior component: physical barriers – intact skin and mucous membranes ´ Interior component: antimicrobial proteins, WBC (phagocytosis) ´ The first line of cellular defense ´ Phagocytes – macrophages, neutrophils, natural killer cells - Skin ´ Squamous epithelium – unattractive for most microorganisms ´ Sweat and sebum contain lysozyme ´ Inhabited by many harmless bacteria (compete with harmful ones) - Mucous membranes  ´ Covered in mucus – traps microorganisms ´ Respiratory tract – ciliated cells transport debris out ´ Acidic environment – urinary, reproductive tracts ´ Continuous flow of fluid – digestive, urinary tracts ´ Competing local beneficial microflora ´ Rapid renewal of epithelial cells Macrophages - present in normal tissue ´ Essential in long-lasting infections ´ First to encounter pathogens and perform phagocytosis ´ Attract more white blood cells to the site (mostly neutrophils) ´ Also remove dead cells and tissue ´ Neutrophils - important in the early phases of infection ´ Natural killer cells – kill virus-infected and cancer cells - Neutrophils ´ Amoeboid movement – move by changing shape ´ Diapedesis – movement through capillary wall into tissue ´ Chemotaxis – attraction by several substances to the affected site ´ Affects neutrophil movements at a 0.1 mm distance - Neutrophils ´ Phagocytosis – engulf foreign particles Intracellular degradation ´ Opsonins (e.g. antibodies) – mark pathogens for phagocytosis ´ Lifespan is shortened by phagocytosis ´ Dominate acute infections - Macrophages – “big eaters” - Monocytes (immature form) circulate in the bloodstream ´ Little ability to attack pathogens - Macrophages (mature form) ´ Present in normal tissues ´ Extensively recruited to sites of infection ´ Combat long-lasting infections Adaptive: Different white blood cells involved – lymphocytes ´ B-lymphocytes – release antibodies ´ T-lymphocytes – kill intracellular antigens 60. The physiological meaning of lipids in the body? Neutral, polar and brown fat, their physiological meaning? Fat splitting process in tissues? Lipids comprise a group of naturally occurring molecules that include fats, sterols, phospholipids, and others. Lipids are made of glycerol and fatty acids Relatively insoluble in water Soluble in nonpolar solvents such as: Ether Chloroform Benzole Acetone  Lipids are stored in adipose tissue Serve as thermal insulator Nonpolar lipids serve as electrical insulator in nerves (allowing rapid propagation of depolarization waves along myelinated nerves) Lipids and proteins (lipoproteins) are important components of cell and mitochondrial membranes Lipoproteins serve as means of transport of lipids in blood 1. Simple (neutral) lipids (Fats(triglycerides) and oils(trigrycelors); Triglycerydes: Functions: Energy source – 9,3kcal per gram Form of stored energy in adipose tissue Insulation and protection Carrier for fat-soluble vitamins (K, E, D, A) Serve as protectant to kidneys and intestines Protect skin from maceration and drying Waxes are produced naturally by skin glands as a protection, to keep it lubricated and water-proof 2. Complex, compound (polar) lipids Phospholipids: lipids containing fatty acids, alcohol, phosphoric acid residue Glycolipids (glycosphingolipids): lipids containing fatty acid, sphingosine, carbohydrate Other complex lipids: lipids such as sulfolipids and aminolipids. (Lipoproteins may also be placed in this category) Phospholipids: Have bigger physiological meaning than neutral fats Structural components of cell membranes Bring water and fat together and are called emulsifiers Take part in lipid absorption Synthesize lipoproteins and transport lipids in blood Prevent fatty liver Form surfactant in lungs Play important role in blood coagulation etc. Lipoproteins: 1.Structural lipoproteins: these are widely distributed in tissues being present in cellular and subcellular membranes. In lungs acting as a surfactant in a complex of a protein and lecithin. In the eye, rhodopsin of rods is a lipoprotein complex. 2.Transport lipoproteins: these are the forms present in blood plasma. They are composed of a protein called apolipoprotein and different types of lipids. (cholesterol, cholesterol esters, phospholipids and triglycerides). As the lipid content increases, the density of plasma lipoproteins decreases. Chylomicrons VLDL – very low density lipoproteins LDL – low density lipoproteins HDL – high density lipoproteins  Free fatty acids Brown adipose tissue – much higher density of mitochondria than in normal adipose tissue Present in many newborn animals (not pigs) Birds do not have brown adipose tissue Located in front of and between shoulder blades, around kidneys Nearly all energy released by it is converted to heat 31. Ticket 61. Why are veins called volume blood vessels? What provides (promotes) blood circulation in veins? Venous pulse, its determination. Veins are volume or capacity (depot) blood vessels. Why? ○ They stretch easily and fill with blood. ○ As the veins empty, blood flow to the heart and arteries increases. Veins regulate blood flow to the heart! Blood flow conditions are worse in veins than in arteries. Why? ○ Because the pressure drop is smaller than in the arteries From the extremities, the blood must flow through the veins against the earth’s gravity. The return of blood through the veins to the heart is promoted by: Skeletal muscles Venous valves. As people get older, the venous valves “disappear”, and as a result, it is difficult for blood to return to the heart through the veins (especially from the veins of the legs). Blood accumulates in the veins of the legs, which can cause them to expand. Respiratory movements. During inspiration, the pressure in the left vena cava decreases. A greater drop in pressure and it is easier for blood to flow into the thoracic veins and further into the heart. The suction action of the heart. The heart also acts as a pump. During ventricular systole, blood is injected into the arteries, while atria are in diastole. The atrioventricular septum bends towards the ventricle, the atria expand and “draw” blood from the veins. Arterial pulsation. Veins are usually located next to arteries, that “massage” the veins. Venous pulse Venous pulse is the volume fluctuations of the veins (detected in veins close to the heart). The maximum venous pulse filling is observed during atrial systole, blood does not flow from the veins into the atria. Blood accumulates in the large veins, increasing the volume of the veins.  The minimal filling is observed during ventricular systole, because the atria are in diastole – blood is sucked from the veins and flow into the atria. The volume of the veins decreases rapidly. As a result, venous volume fluctuations occur – venous pulse. Venous pulse This is the volume pulse Reflects the activity of the right side of the heart It is found only in the large veins close to the heart Cannot be palpated, is only recordable. 62. What are the main hormones that regulate the appetite? Regulated by a center located in the hypothalamus. The feeling of hunger is caused by: Afferent nerves that leave the stomach and intestines. They signal about an empty stomach and increased intestinal peristalsis. Changes in the physical-chemical properties of blood - i.e. "Starvation/hunger blood", when glucose levels are lowered and hydrogen is increased. After the activation of the feeling of hunger in the hemisphere, the so-called a feeling of hunger occurs, which causes the animal to seek food. After eating, the feeling of hunger is replaced by a feeling of satiety - it reduces the intensity of food intake. Are distinguished: Sensory satiety - it arises from the receptors of a stuffed stomach; Metabolic satiety - this is caused by glucoreceptors in the blood vessels that report an increase in the level of glucose in the blood. Ghrelin and leptin Ghrelin and leptin are two hormones that are of great interest in appetite regulation Leptin is commonly considered anorexigenic (i.e.,appetite suppressant), while ghrelin is orexigenic (i.e., appetite stimulant) Ghrelin is a peptide hormone produced in the pancreas and released from the stomach wall when the stomach is empty. This stimulates the excitatory primary neurons, and therefore stimulates appetite. When the stomach is full, ghrelin release is inhibited, thus the appetite stimulus is also inhibited. Leptin is a peptide hormone released into the blood by adipocytes (fat cells). Leptin stimulates the inhibitory neurons and inhibits the excitatory neurons in the arcuate nucleus to cause suppression of appetite. Insulinis a hormone released from beta cells in the islets of Langerhans of the pancreas. This suppresses appetite in a similar way to leptin. PYY (full name – peptide tyrosine tyrosine) is a short peptide hormone released by cells in the ileum and colon in response to feeding. It inhibits the excitatory primary neurons of the arcuate nucleus. This causes appetite suppression.  32. Ticket 63. The splitting of cellulose and carbohydrates in the forestomach of ruminants. Cellulose and carbohydrate breakdown in the forestomachs 60-70% of digestible cellulose is broken down in the forestomachs. The rest is passed further through the digestive tract to the large intestine. Cellulose in ruminants is extremely important for the maintenance of normal motility in the forestomachs and the digestive tract as a whole. The bacterial enzyme cellulase breaks down cellulose into disaccharides – cellobiose, which is further broken down into 2 glucose molecules to form the monosaccharide glucose. Glucose is further involved in the fermentation process, eventually forming volatile fatty acids, but this occurs through the stages of pyruvic and lactic acid. Cellulose→cellobiose→glucose→pyruvic acid→lactic acid→volatile fatty acids. Cellulolytic bacteria is a very important group of bacteria that allow ruminants to eat and digest roughage. They are very sensitive to changes in rumen pH. (pH