Lecture_02_Cardiovascular,_Lymphatic_System,_and_Nervous_System.pdf

New Era University College of Agriculture ANSC121-18 – ANIMAL SCIENCE 1: INTRODUCTION TO ANIMAL SCIENCE Second Semester, AY 2020-2021 COURSE DESCRIPTION Principles of anim...

New Era University College of Agriculture ANSC121-18 – ANIMAL SCIENCE 1: INTRODUCTION TO ANIMAL SCIENCE Second Semester, AY 2020-2021 COURSE DESCRIPTION Principles of animal physiology, nutrition, and breeding and its relevance to the production, processing, and marketing of animal products COURSE LEARNING OUTCOMES At the end of the course, the students are expected to: 1. Recognize the significance of animal science as a field in agriculture 2. Explain the basic concepts and principles of animal physiology, breeding, nutrition, slaughtering, processing and marketing of animal products as they relate to animal productivity 3. Demonstrate basic skills in evaluating feed ingredients, formulating simple animal rations, slaughtering animals, and processing of products Week 2 - Lecture MODULE 2 – CARDIOVASCULAR, LYMPHATIC, & NERVOUS SYSTEM This module begins by explaining the concepts of anatomy, physiology, and homeostasis. Then, the discussion will proceed on the cardiovascular system with the focus on the parts of the heart, blood circulation, types of blood vessels, and cell components of the blood. There will also be a brief discussion on the lymphatic system, its parts, and functions. Finally, the nervous system will be tackled with emphasis on its functions and divisions. LEARNING OUTCOMES At the end of the module, the student should be able to: 1. Define anatomy, physiology, and homeostasis 2. Identify the parts and functions of the cardiovascular, lymphatic, and nervous systems. 3. Differentiate systole and diastole 4. Differentiate the types of blood vessels 5. Differentiate the different blood cells 6. Differentiate the types of neurons 7. Explain the circulation of blood in the body 8. Explain the flow of lymph inside the body 9. Explain the reflex arc and transmission of an impulse 10. Discuss the divisions of the nervous system Anatomy, Physiology, and Homeostasis The first part of this course focuses on anatomy and physiology. As discussed in the previous lesson, anatomy is the science that focuses on the structural component of the animal body and the relation of the different body parts. On the other hand, physiology is the science that deals with the functions of organs and different organ systems in the body. Homeostasis is one of the main themes of physiology wherein living organisms try to maintain their internal environment at a constant state. To achieve this state, different systems of the body work together to respond to the various stress coming from the external environment. Some examples include maintaining normal body temperature, the optimum pH level of body fluids, and correct levels of electrolytes.  Cardiovascular System Parts Blood Blood is composed of cells and formed elements that are suspended in plasma. It serves as the transport medium of different substances throughout the animal body. Blood vessels These are tubes that connect with each other forming a system where blood can circulate. Heart This is the organ responsible for pumping blood throughout the body. Heart Figure 1. Parts of the heart Parts of the Heart 1. Pericardial sac – the tissue covering the heart that is characterized as thin but tough. 2. Chambers of the heart Atrium – the chambers located on the upper portion of the heart that collects blood from the veins. The right atrium receives blood from the superior and inferior vena cava while the left atrium receives blood from the pulmonary veins. Ventricles – the chamber found on the lower portion of the heart that moves blood to arteries. The right ventricle pumps blood to the pulmonary arteries while the left ventricle transports blood to the aorta. 3. Atrioventricular valves or A-V valves – these are valves positioned between the atria and ventricles that prevent the backflow of blood. Tricuspid valve – the A-V valve between the right atrium and right ventricle. Bicuspid or mitral valve – the A-V valve between the left atrium and left ventricle. 4. Semilunar valves – the valves that prevent the backflow of blood as it moves from the ventricles to arteries. Pulmonary valve – located between the right ventricle and the pulmonary trunk. Aortic valve – located between the left ventricle and the aorta. Cardiac Cycle The cardiac cycle is defined as “one complete cycle of cardiac contraction and relaxation” (Frandson, Wilke, & Fails, 2009). This also represents the heartbeat. The cardiac cycle is divided into two phases: systole and diastole. During systole, the chambers of the heart are contracting and blood is pumped out. While during diastole, the chambers of the heart are in a relaxed state. It is also the time when the chambers are filled with blood. “Lub-dub” is the sound of the heart. The first sound, “lub”, is produced when the A-V valves close. On the other hand, the second sound, “dub”, is produced when the semilunar valve closes. The production of the second sound indicates that the systole ends and the diastole begins.  Figure 2. Systole and Diastole Blood Vessels Figure 3. Different kinds of blood vessels A. Arteries Blood vessels that transport blood away from the heart. Generally, oxygenated blood flows in the arteries.  Pulmonary arteries, however, carry deoxygenated blood from the heart to the lungs. The wall of the arteries is characterized as thick and elastic. B. Veins Blood vessels that transport blood back to the heart. Generally, deoxygenated blood flows in the veins. Pulmonary veins, however, carry oxygenated blood from the lungs to the heart. Compared to arteries, veins are larger in diameter but their walls are thinner. C. Capillaries Capillaries are the smallest blood vessels. Water, oxygen, and nutrients present in the blood move to the tissue cells through the semipermeable wall of capillaries. Waste products coming from the cells also enter the bloodstream through the capillary walls. D. Arterioles and Venules Arteries branch out into smaller blood vessels called arterioles. On the other hand, arterioles branch out to form capillaries. These capillaries converge into venules while venules converge to form veins. Blood Circulation Figure 5. Flow chart of blood circulation Figure 4. Parts of the heart Figure 4 illustrates the flow of blood in the heart. The arrows serves as the guide. To memorize it easier, please refer to Figure 5. Pulmonary and Systemic Circulation Pulmonary Circulation – blood circulation inside the lungs that is separate from the circulation in other body parts. Flow of blood: From the left ventricle, deoxygenated blood is transported to the lungs through the pulmonary arteries. On the capillaries inside the lungs, gas exchange occurs. The oxygenated blood moves from the lungs back to the left atrium through the pulmonary veins. This completes the pulmonary circulation. Systemic Circulation – blood circulation on the remaining parts of the body. Flow of blood: The oxygenated blood that returns to the heart is pumped to different body parts. After supplying the oxygen to various body parts, the deoxygenated blood goes back to the heart. Blood Functions of Blood Delivers nutrients obtained from the digestive tract Carries oxygen from lungs to various cells of the body Moves carbon dioxide from cells to the lungs Brings waste products from the cells to the kidney for excretion Transports hormones Aids in regulation of body temperature Helps in maintaining body fluids at constant pH Assists in preventing too much blood loss through blood coagulation Helps defend the body Components of Blood Figure 6. Components of blood  Plasma – the fluid portion of the blood that is composed of 92% water. Aside from this, it also has electrolytes, nutrients, wastes, and proteins. Blood cells - composed of red blood cells (RBC), white blood cells (WBC), and platelets. a. Red Blood Cells (RBC) It is also called erythrocytes. It has a biconcave disk shape and has no nucleus. Hemoglobin is a major component of RBCs. Hemoglobin is responsible for the transport of oxygen and carbon dioxide throughout the body. b. Platelets It is also called thrombocytes. Similar to RBCs, it has no nucleus. When an animal is injured, platelets work together to form a blood clot. This prevents too much blood loss on the damaged blood vessel. c. White Blood Cells (WBC) It is also called leukocytes. Unlike RBC and platelets, WBC has a nucleus. WBCs are further classified as granulocytes and agranulocytes. Granules are present on granulocytes while agranulocytes do not have. Examples of granulocytes include neutrophils, eosinophils, and basophils. o Neutrophils – are phagocytes that surround and consume bacteria in order to destroy them. o Eosinophils – responds during an allergic reaction or when parasites enter the body o Basophils - also involved in allergic reaction response Examples of agranulocytes are monocytes and leukocytes. o Monocytes – later develop into macrophages. It is also phagocytotic in nature. o Lymphocytes – performs various functions depending on the type. Some lymphocytes can detect and destroy virus-infected cells while others can produce antibodies. Lymphatic System Functions of the Lymphatic System Collects tissue fluids  Some fluid of the blood leaks out from the blood capillaries into the tissues. Through the help of the lymphatic system, these tissue fluids are drained and transported back to the veins. Produces immune cells Some organs in the lymphatic system are capable of producing immune cells called lymphocytes. Helps defend the body against infection Once the tissue fluids enter the lymphatic vessels they are called lymph. Lymph contains fluid, white blood cells (commonly lymphocytes), and some proteins. However, it also contains microorganisms and other foreign substances. As the lymph travels through the lymphatic system, immune cells look for harmful microorganisms and attack them. This helps prevent infections. Parts of the Lymphatic System Figure 7. Blood vessels and lymphatic vessels. Lymphatic capillaries are the smallest lymphatics and are responsible for the absorption of fluids that accumulate in the tissues. From the capillaries, the fluid (lymph) moves to large lymphatic vessels. Lymphatic vessels help move the lymph to the veins and eventually into the heart. Lymph nodes are composed of lymphoid tissues and located in various areas along the lymphatic vessels. One of its functions is to filter the lymph. Inside the lymph nodes are macrophages and lymphocytes that destroy the filtered foreign  substances and microorganisms. The filtered lymph then goes to the outgoing lymphatic vessels. Figure 8. The lymphatic system. Adapted from Anatomy and Physiology of Animals. Copyright 2015 by Wikibooks. Organs of the Lymphatic System a. Spleen A lymphoid organ that is located near the stomach. One of its functions is to destroy old or worn-out red blood cells and breakdown the hemoglobin into iron. It is also capable of storing red blood cells. Spleen also contains lymphocytes. b. Thymus A lymphoid organ that is located near the heart. Lymphocytes are initially produced in the thymus before it moves to other lymphatic tissues. c. Tonsils It is made up of clusters of lymph nodules. Nervous System Functions Sensory function  Perceives changes outside and inside of the body Uses the senses and body mechanisms that detect pain, temperature, pressure, and chemicals Integrative function Registers the information received from the different organs of the body. This information is then processed to determine the correct response. Motor function Initiates and control the contraction of skeletal, smooth, and cardiac muscles thereby allowing movement of different body parts Controls the contractions of muscle and secretions of the gland as a response to the information obtained by the sensory organs Parts Brain Spinal cord Nerves Neurons or nerve cells are the main functional cells in the nervous system. These cells are capable of conducting nerve impulses. These nerve impulses are similar to electrical impulses and are responsible for the transmission of messages throughout the body. Figure 9. Neuron Parts of the nerve cells Neurons have a cell body that contains a nucleus and other organelles. Aside from this, they also have nerve processes, axon and dendrites, that branches out from the cell body. Axon - transmits electrical signals away from cell bodies. A neuron has only one axon. A fatty material called myelin sheath covers the axon and helps speeds up the transmission of electrical impulses. Dendrites – transmits electrical signals toward the cell body. A neuron may have one or multiple dendrites. Types of neurons based on the direction of impulse conduction Figure 10. Sensory, relay, and motor neurons Sensory or afferent neurons can get information both from the inside and outside of the body through sensory receptors. Examples of sensory receptors are ears, eyes, and skin. From these receptors, sensory neurons transfer the nerve impulses to the brain and spinal cord. Once the nerve impulses reach the central nervous system (brain and spinal cord), the information will be processed. Then, action will be done as a response which includes muscle movement, gland secretion, or exhibition of certain behavior. For the muscles to move and glands to release secretions, the brain and spinal cord transmit nerve impulses through the motor or efferent neurons to the muscle and glands. Found in the brain and spinal cord, the interneuron or relay neurons connect the sensory and motor neurons. Reflex Reflex is a quick automatic response to a stimulus. This involves actions that were done unconsciously. Examples of reflex actions include removing one’s hand from a hot object after accidentally touching it. Based on the given example, sensory receptors on the skin send nerve impulses after touching the hot object. The nerve impulse travels to the spinal cord through the sensory neuron. The interneuron in the spinal cord receives the nerve impulse and transfer it to the motor neuron. The nerve impulse will then reach the muscle of the hand causing it to contract and move away from the hot object. The pathway traveled by the nerve impulse from the detection of stimulus (high temperature from the hot object) to the response (movement of hand) is called the reflex arc. Figure 11. Reflex arc Transmission of Nerve Impulse Synapse It is the connection between two adjacent neurons where transmission of information occurs. Neurotransmitters These are chemical mediators released on the synaptic cleft and binds to the receptors. Example: acetylcholine, norepinephrine, GABA, glutamate  Synaptic Cleft The gap between the presynaptic cell and postsynaptic cell where neurotransmitters accumulate. Receptors These are where neurotransmitters bind in the postsynaptic cell. Figure 12. Synapse Steps in the transmission of nerve impulses in a chemical synapse. 1. Nerve impulse in the presynaptic cell stimulates the release of neurotransmitters 2. Neurotransmitters move out to the synaptic cleft 3. Neurotransmitters attach to the receptors of the postsynaptic cells 4. The new nerve impulse is generated in the postsynaptic cell Divisions of Nervous System The nervous system can be divided into two divisions: the central nervous system and peripheral nervous system. Figure 13. The nervous system of a horse A. Central Nervous System (CNS) – consist of brain and spinal cord B. Peripheral Nervous System (PNS) – composed of nerves connected to the brain and spinal cord. a. Cranial nerves – the nerves connected to the brain. There are twelve (12) pairs of cranial nerves and below are some of the examples: Olfactory nerves – transmit impulses to the brain from the olfactory organ of the nose; smell Optic nerves – transmit impulses to the brain from retina of eyes; sight Auditory nerves – transmit impulses to the brain from the cochlear of the inner ear; hearing Vagus nerve – regulates the muscles involved in swallowing as well as heart, airways, lungs, stomach, intestines b. Spinal nerves – the nerves connected to the spinal cord. An example is a sciatic nerve which is made up of various nerves making it the largest spinal nerve. It is located at the hind leg. In addition, the PNS can be further divided into the somatic nervous system and autonomic nervous system. A. Somatic Nervous System Involved in the voluntary control of skeletal muscles Allows muscle to move or adjust in response to the stimulus coming from the environment B. Autonomic Nervous System Involved in the regulation of organs and other body structures functions that are not under conscious or voluntary control These include glands and visceral organs containing smooth and cardiac muscles The autonomic nervous system is divided into two divisions: sympathetic and parasympathetic division. A. Sympathetic Division Involved in the “flight, fright, fight” response caused by different emotions like fear, anxiety, and rage. Allows an animal to either run away from an attacker or confront it and defend itself. Below are some of the effects on the organs when the sympathetic division is active: o Dilation of the pupil o Accelerated heartbeat o More blood flowing to skeletal muscles o Opening of airways in lungs o Release of glucose from the liver o Inhibition of salivation and digestion B. Parasympathetic Division Involved in the “housekeeping” functions Helps maintain a regular heartbeat and breathing as well as digestion, urination, and defecation Active when the body is at a relaxed state Below are some of the effects when the parasympathetic division is active: o Constriction of the pupil o Relaxed heartbeat o Release of saliva in the mouth o Promotes gastrointestinal motility and digestion o Shrinking of airways o The urinary bladder is emptied through urination  Nervous System Central Nervous Peripheral System Nervous System Somatic Nervous Autonomic Brain Spinal Cord System Nervous System Sympathetic Parasympathetic Division Division Figure 14. The divisions of the nervous system References Carroll, R. G. (2007). Elsevier's Integrated Physiology. Philadelphia: Mosby, Inc. Frandson, R. D., Wilke, L. W., & Fails, A. D. (2009). Anatomy and Physiology of Farm Animals (7th ed.). Iowa: John Wiley & Sons, Inc., Publication. Kay, I. (1998). 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