Science Grade 10 Learner's Material PDF

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VISIT DEPED TAMBAYAN http://richardrrr.blogspot.com/ 10 1. Center of top breaking headlines and current events related to Department of Education. 2. Offers free K-12 Materials you can use and share. Science PY Learner’s Material Unit 3 O C ED This book was collaboratively developed and reviewed by educators from public and private schools, colleges, and/or universities. We encourage EP teachers and other education stakeholders to email their feedback, comments, and recommendations to the Department of Education at [email protected]. We value your feedback and recommendations. D Department of Education Republic of the Philippines i All rights reserved. No part of this material may be reproduced or transmitted in any form or by any means - electronic or mechanical including photocopying – without written permission from the DepEd Central Office. First Edition, 2015.  Science – Grade 10 Learner’s Material First Edition 2015 Republic Act 8293, section 176 states that: No copyright shall subsist in any work of the Government of the Philippines. However, prior approval of the government agency or office wherein the work is created shall be necessary for exploitation of such work for profit. Such agency or office may, among other things, impose as a condition the payment of royalties. Borrowed materials (i.e., songs, stories, poems, pictures, photos, brand names, trademarks, etc.) included in this book are owned by their respective copyright holders. DepEd is represented by the Filipinas Copyright Licensing Society (FILCOLS), Inc. in seeking permission to use these materials from their respective copyright owners. PY All means have been exhausted in seeking permission to use these materials. The publisher and authors do not represent nor claim ownership over them. Only institutions and companies which have entered an agreement with FILCOLS and only within the agreed framework may copy from this Learner’s Material. Those who have not entered in an agreement with FILCOLS must, if they wish to copy, O contact the publishers and authors directly. Authors and publishers may email or contact FILCOLS at [email protected] or (02) 439-2204, respectively. Published by the Department of Education C Secretary: Br. Armin A. Luistro FSC Undersecretary: Dina S. Ocampo, PhD D Development Team of the Learner’s Material E Authors: Herma D. Acosta, Liza A. Alvarez, Dave G. Angeles, Ruby D. Arre, Ma. Pilar P. Carmona, Aurelia S. Garcia, Arlen Gatpo, Judith F. Marcaida, Ma. Regaele A. Olarte, Marivic S. Rosales, Nilo G. Salazar EP Reviewers: Eligio C. Obille Jr., Marlene B. Ferido, Ma. Helen DH Catalan, Vic Marie Camacho, Lilia M. Rabago, Cerilina M. Maramag Illustrators: Joseph V. Bales, Ramon C. Gatpo, Regaele A. Olarte, Marivic S. Rosales, Ruel C. Quindoy, Antonio I. Basilla, Jose Leo Vic O. Albaño DepEd Specialists: Joseph R. Jacob, Maria Amparo R. Ventura D Photo Credits: Herma D. Acosta, Dave G. Angeles, Liza A. Alvarez, Ruby D. Arre, Aurelia S. Garcia, Judith F. Marcaida, Regaele A. Olarte, Jane Chavarria, Nilo G. Salazar Layout Artists: Matthew Daniel V. Leysa and Mary Grace Ann G. Cadisal Printed in the Philippines by REX Book Store, Inc. Department of Education-Instructional Materials Council Secretariat (DepEd-IMCS) Office Address: 5th Floor Mabini Building, DepEd Complex Meralco Avenue, Pasig City Philippines 1600 Telefax: (02) 634-1054, 634-1072 E-mail Address: [email protected] ii All rights reserved. No part of this material may be reproduced or transmitted in any form or by any means - electronic or mechanical including photocopying – without written permission from the DepEd Central Office. First Edition, 2015.  TABLE OF CONTENTS Unit 3: Living Things and Their Environment Overview Module 1: Coordinated Functions of the Nervous, Endocrine, and Reproductive Systems I. Introduction ------------------------------------------------------------------------------225 II. Learning Competencies/Objectives -----------------------------------------------225 III. Pre-assessment ------------------------------------------------------------------------226 PY IV. Reading Resources and Instructional Activities---------------------------------228 Activity 1: Break It Down! -------------------------------------------------------230 Activity 2: How Fast Is Your Reaction? --------------------------------------233 Activity 3: A Nervous Trip --------------------------------------------------------237 O Activity 4: Who’s in Control? ---------------------------------------------------242 Activity 5: What Went Wrong? -------------------------------------------------245 C Activity 6: Mark My Calendar! --------------------------------------------------252 V. Summary/Synthesis/Feedback ------------------------------------------------------257 D VI. Summative Assessment -------------------------------------------------------------259 Glossary of Terms -----------------------------------------------------------------260 E References and Links ------------------------------------------------------------261 EP Module 2: Heredity: Inheritance and Variation I. Introduction --------------------------------------------------------------------------------263 II. Learning Competencies/Objectives-------------------------------------------------264 D III. Pre-Assessment ------------------------------------------------------------------------264 IV. Reading Resources and Instructional Activities---------------------------------266 Activity 1: Getting to Know the DNA and RNA Structure ----------------266 Activity 2: DNA Makes DNA ----------------------------------------------------269 Activity 3: What’s the Message ------------------------------------------------273 Activity 4: Relay the Message --------------------------------------------------276 Activity 5: Trace the Code -------------------------------------------------------280 Activity 6: Chromie Change ----------------------------------------------------284 All rights reserved. No part of this material may be reproduced or transmitted in any form or by any means - electronic or mechanical including photocopying – without written permission from the DepEd Central Office. First Edition, 2015.  V. Summary/Synthesis/Feedback ------------------------------------------------------294 VI. Summative Assessment -------------------------------------------------------------295 Glossary of Terms -----------------------------------------------------------------296 References and Links ------------------------------------------------------------298 Module3: Biodiversity and Evolution I. Introduction --------------------------------------------------------------------------------299 II. Learning Competencies/Objectives-------------------------------------------------299 III. Pre-Assessment ------------------------------------------------------------------------300 PY IV. Reading Resources and Instructional Activities --------------------------------302 Activity 1A: Where Do I Belong ------------------------------------------------304 Activity 1B: What’s My Age? ----------------------------------------------------306 O Activity 2: AHA! Analogous! Homologous! ----------------------------------310 Activity 3: So, Who is My Relative? -------------------------------------------311 C Activity 4: Let’s Compare --------------------------------------------------------313 Activity 5: Follow the Track -----------------------------------------------------318 D Activity 6: Survivor ----------------------------------------------------------------319 V. Summary/Synthesis/Feedback-------------------------------------------------------322 E VI. Summative Assessment -------------------------------------------------------------323 EP Glossary of Terms------------------------------------------------------------------325 References and Links-------------------------------------------------------------326 Module 4: Ecosystem: Biodiversity D I. Introduction --------------------------------------------------------------------------------328 II. Learning Competencies/Objectives ------------------------------------------------328 III. Pre-Assessment ------------------------------------------------------------------------329 IV. Reading Resources and Instructional Activities --------------------------------329 Activity 1: Classifying the Value of Biodiversity ----------------------------330 Activity 2: Dependent or Independent? --------------------------------------336 Activity 3: Analyzing Environmental Issues ---------------------------------338 All rights reserved. No part of this material may be reproduced or transmitted in any form or by any means - electronic or mechanical including photocopying – without written permission from the DepEd Central Office. First Edition, 2015.  Activity 4: Biodiversity Status in the Community ---------------------------340 Activity 5: Product Creation -----------------------------------------------------341 Activity 6: Showcasing of Products -------------------------------------------344 V. Summary/Synthesis/Feedback ------------------------------------------------------344 VI. Summative Assessment -------------------------------------------------------------345 Glossary of Terms -----------------------------------------------------------------347 References and Links ------------------------------------------------------------347 PY O C E D EP D All rights reserved. No part of this material may be reproduced or transmitted in any form or by any means - electronic or mechanical including photocopying – without written permission from the DepEd Central Office. First Edition, 2015.  UNIT 3 Living Things and Their Environment PY O C E D EP D 223 All rights reserved. No part of this material may be reproduced or transmitted in any form or by any means - electronic or mechanical including photocopying – without written permission from the DepEd Central Office. First Edition, 2015.  UNIT 3: Living Things and Their Environment Overview In the past years, you have studied about the coordinated functions of the digestive, respiratory, and circulatory systems. You have learned that nutrients enter the bloodstream and combine with oxygen taken in through the respiratory system. You have also understood the structure of genes and chromosomes, and the functions they perform in the transmission of traits from parents to offspring. You have discovered that some species that once existed are now extinct, and that they become extinct when they fail to adapt to changes in the environment. You have become familiar about how plants capture energy PY from the sun and store energy in sugar molecules through photosynthesis, and learned that stored energy is used by cells during cellular respiration. You have found out that these two processes are interrelated. All modules in Grade 10 Unit 3 Living Things and Their Environment O present mental and hands-on activities that will enable you to apply science concepts and inquiry skills in addressing real-world problems through scientific investigations. These instructional activities are designed to enhance your C knowledge, understanding, skills, and ability to transfer learning. There are four modules in this quarter, namely: D Module 1: Coordinated Functions of the Nervous, Endocrine, and Reproductive Systems E Module 2: Heredity: Inheritance and Variation EP Module 3: Biodiversity and Evolution Module 4: Ecosystems: Biodiversity D At the end of Grade 10, you should have already developed scientific, technological, and environmental literacy that will lead you to rational choices on any issue that you will face in life. 224 All rights reserved. No part of this material may be reproduced or transmitted in any form or by any means - electronic or mechanical including photocopying – without written permission from the DepEd Central Office. First Edition, 2015.  Suggested time allotment: 12 to 14 hours Unit 3 COORDINATED FUNCTIONS MODULE OF THE NERVOUS, 1 ENDOCRINE, AND REPRODUCTIVE SYSTEMS PY I. Introduction The human body is made up of different systems that coordinate with O one another in order to perform their functions well. If any part of these organ systems malfunctions, the body will become unbalanced. The instability caused by the malfunctioning of one system cannot be made stable by other systems C because each system has its own function in the body. You have studied in the past that human body systems are the combined functional units composed of various organs that work in full coordination with one other. In Grade 9, you have already studied how the circulatory and respiratory systems work D together and how lifestyle affects these systems. Now you will learn about the coordinated functions of the reproductive, endocrine, and nervous systems. E As you go through this module, you will be able to understand organisms having feedback mechanisms, are coordinated by the nervous and endocrine EP systems. You will also learn how these feedback mechanisms help organisms maintain homeostasis to reproduce and survive. II. Learning Competencies/Objectives D At the end of this module, you are expected to: 1. Describe the parts of the nervous, endocrine, and reproductive systems, along with their functions. 2. Explain the role of hormones involved in the female and male reproductive systems. 3. Describe the feedback mechanisms in regulating processes in the female reproductive system. 4. Describe how the nervous system coordinates and regulates feedback mechanisms to maintain homeostasis. 225 All rights reserved. No part of this material may be reproduced or transmitted in any form or by any means - electronic or mechanical including photocopying – without written permission from the DepEd Central Office. First Edition, 2015.  In Module 1, you will answer the following key questions: How do the nervous, endocrine, and reproductive systems perform coordinated functions? How do hormones work to regulate various mechanisms inside the human body? How do feedback mechanisms help organisms to maintain homeostasis in order to reproduce and survive? III. Pre-Assessment Odd Organ Out PY Directions: Study each set of diagrams showing different organs of the human body. Then, determine which organ does not belong to the group by naming it on the space provided, on the second column of the table. Lastly, write your O explanation on the third column why the organ should not be included in the group. C Group of Organs Odd-One Out Reason E D good-health-guide. eweb.furman.edu blogspot.com EP cervical region thoracic region D lumbar region sacral region coccygeal region education-portal.com ninds.nih.gov 226 All rights reserved. No part of this material may be reproduced or transmitted in any form or by any means - electronic or mechanical including photocopying – without written permission from the DepEd Central Office. First Edition, 2015.  Group of Organs Odd-One Out Reason medindia.net myoptumhealth.com PY wisegeek.org academymedical.com O C globehealingcenter.com hormone.org E D EP tooloop.com facstaff.gpc.edu D 227 All rights reserved. No part of this material may be reproduced or transmitted in any form or by any means - electronic or mechanical including photocopying – without written permission from the DepEd Central Office. First Edition, 2015.  sandrocastelli.com tooloop.com PY health.allrefer.com Lackfoundation.org You have studied that cells make up a tissue, then tissues make up an organ, and organs make up a system. Now, you will first try to understand the O organ system before you go to the cellular level to know how the individual cells of the nervous system work. IV. Reading Resources and Instructional Materials C The Nervous System The Structure of the Nervous System E D EP D Figure 1. The human nervous system 228 All rights reserved. No part of this material may be reproduced or transmitted in any form or by any means - electronic or mechanical including photocopying – without written permission from the DepEd Central Office. First Edition, 2015.  Your nervous system connects all your body parts and transmits signals from one part to another. It is a system of cells, tissues, and organs that regulates the body’s responses to internal and external stimuli. Each part of the nervous system has a specific role as it functions as an important part of a system. Major Divisions and Parts of the Nervous System 1. Central Nervous System (CNS) The CNS serves as the main processing center for the entire nervous system. It consists of two main components, namely the: a. Brain PY This is an organ located within the skull that functions as organizer and distributor of information for the body. It has three main parts: Cerebrum – large, upper part of the brain that controls activity and O thought. C Cerebellum – the part under the cerebrum that controls posture, balance, and coordination. Brain Stem – the part that connects the brain to the spinal cord D and controls automatic functions such as breathing, digestion, heart rate, and blood pressure. E b. Spinal Cord This serves as a channel for signals between the brain and the rest of EP the body, and controls simple musculoskeletal reflexes without input from the brain. 1. Peripheral Nervous System (PNS) The PNS connects the central nervous system to the organs and limbs. D It has two main divisions: a. Somatic Nervous System This system is associated with the voluntary control of body movements and has two main parts: Spinal Nerves – the nerves that carry motor and sensory signals between the spinal cord and the body. 229 All rights reserved. No part of this material may be reproduced or transmitted in any form or by any means - electronic or mechanical including photocopying – without written permission from the DepEd Central Office. First Edition, 2015.  Cranial Nerves – the nerve fibers that carry information into and out of the brain stem b. Autonomic Nervous System This system is associated with the involuntary control of body movements and has two subdivisions: Sympathetic - it is activated when the body is in a dynamic role or stress. (e.g., increased heart rate and breathing, dilation of pupil, sweating, etc.) Parasympathetic - it maintains body functions and restores the PY body to normal or relaxed mode. Now, test your understanding of the basic organization of the nervous system by doing Activity1. Activity 1 O C Break it Down! (Adapted from DepEd Project EASE, Module 9: Life Support Systems, pp. 4-6) D Objective: Identify the parts of the nervous system E Procedure: EP Using the given graphic organizer, fill in the missing parts to complete the entire concept showing the structure of the nervous system. D 230 All rights reserved. No part of this material may be reproduced or transmitted in any form or by any means - electronic or mechanical including photocopying – without written permission from the DepEd Central Office. First Edition, 2015.  Major Divisions Main Components Main Divisions PY Brain Somatic Nervous System Main Parts O C Subdivisions D Main Parts E EP D Guide Questions: Q1. How will you differentiate the Central Nervous System (CNS) and the Peripheral Nervous System (PNS) in terms of their functions? Q2. What might happen to the human body if one part of the nervous system fails to carry out its function properly? 231 All rights reserved. No part of this material may be reproduced or transmitted in any form or by any means - electronic or mechanical including photocopying – without written permission from the DepEd Central Office. First Edition, 2015.  The Nerve Cell The basic unit of the nervous system is the nerve cell. Nerve cells are called neurons. Study Figure 2 and look at the different parts of the neuron. There are billions of neurons in the body. Some exist alone. Others are joined together to form organs like the brain and spinal cord. There are twelve to fourteen billions of neurons in one part of the brain alone. A neuron has a cell body containing the nucleus. Projecting out from the cell body are root-like structures. These are the dendrites and axons. Dendrites carry impulses towards the cell body. A cell may have as many as 200 dendrites carrying impulses toward the cell body. A single dendrite can be over one meter PY long. Axons carry impulses away from the cell body. Axons pass impulses to the dendrites of other neurons or cell body of muscle cells. Axons can be grouped together into cable-like bundles called nerves. O C E D Figure 2. The basic parts of a neuron EP Control of Body Processes through the Nervous System The Nerve Impulse D Neurons are cells with the special ability to carry signals or impulses. Thoughts, emotions, learning, and many body functions are carried by nerve impulses in the neurons. A nerve impulse is a combination of an electrical charge and a chemical reaction. A nerve impulse is not a flow of electricity, but an electrochemical signal moving along a neuron. Imagine that you have a board with a row of switches. Quickly click each switch in the row on and off. This will give you an idea of how a nerve impulse travels along a neuron. 232 All rights reserved. No part of this material may be reproduced or transmitted in any form or by any means - electronic or mechanical including photocopying – without written permission from the DepEd Central Office. First Edition, 2015.  A nerve impulse cannot jump from one neuron to another. When a nerve impulse comes to the end of an axon, it produces the chemical, called neurotransmitter, to be released. The chemical crosses the space between neurons called synapse and stimulates the nerve impulse to start in the next dendrite. PY Figure 3. The nerve impulse is sent by neurotransmitters from one neuron to another through a gap called synapse O The nervous system is assisted by five sense organs - the eyes, ears, nose, tongue, and skin. These sense organs are constantly receiving information from the environment and sending messages to the brain. These C senses aid in the survival of human beings. A stimulus (plural: stimuli) is any factor in the environment that may trigger a nerve impulse. A response is a reaction to a stimulus. A stimulus is received by the body and a response is made. An organism must be able to respond to a stimulus in order to survive. D Messages do not travel in both directions along the same neuron. Only E the axon of the neuron releases neurotransmitters that cross the space between neurons. Reaction time is the length of time between application of a stimulus and detection of a response. EP The next activity that you will perform will enable you to understand these concepts better. Use your body’s senses to detect the stimuli in your environment and execute the corresponding response. D Activity 2 How Fast is Your Reaction? (Adapted from DepEd Project EASE, Module 9: Life Support Systems, pp. 7-8) Objective: Measure the length of time of response to catch a dropped object 233 All rights reserved. No part of this material may be reproduced or transmitted in any form or by any means - electronic or mechanical including photocopying – without written permission from the DepEd Central Office. First Edition, 2015.  Materials: metric ruler data chart Procedure: 1. Construct a table like the one given below, to record your data. Centimeters where the ruler fell Trials Eyes open Eyes closed Left hand Right hand Left hand Right hand 1st 2nd PY 3rd 4th 5th Average O 2. Have your partner hold a metric ruler at its end with the highest number in cm. C 3. Place the thumb and forefinger of your left hand close to, but not touching, the end with the lowest number. D 4. When your partner drops the ruler, try to catch it between your thumb and finger. E EP D Figure 4. Measuring the reaction time 234 All rights reserved. No part of this material may be reproduced or transmitted in any form or by any means - electronic or mechanical including photocopying – without written permission from the DepEd Central Office. First Edition, 2015.  5. Record where the top of your thumb is, when you catch the ruler. This number gives how many centimeters the ruler fell. 6. Repeat steps 2 to 5 five more times and record the measurements on the data table that you have constructed earlier. 7. Repeat steps 2 to 5 five more times using your right hand to catch the ruler. 8. Repeat steps 2 to 5 five more times using your left hand with your eyes closed. Your partner will signal you by saying “now” when the ruler drops. PY 9. Repeat steps 2 to 5 five more times using your right hand with your eyes closed. Record your data and observations. 10. Exchange tasks and drop the ruler for your partner. O 11. To complete your data chart, change all the centimeters to seconds by multiplying by 0.01. C 12. After recording all the data, compute for the average by adding up the measurements of all the trials and dividing it by the number of trials. D Guide Questions: (Answers will depend on whether the person is left-handed or right-handed) E Q3. With which hand did you catch the ruler faster when your eyes were open? EP Q4. With which hand did you catch the ruler faster when your eyes were closed? Q5. Did you catch the ruler faster with your eyes open or closed? D Q6. Explain why a message moving along nerve pathways takes time. Q7. Describe the nerve pathway that the message followed when you saw the ruler fall. 235 All rights reserved. No part of this material may be reproduced or transmitted in any form or by any means - electronic or mechanical including photocopying – without written permission from the DepEd Central Office. First Edition, 2015.  KEY CONCEPTS: Neurons have the special ability to carry signals or impulses. A nerve impulse is an electrochemical signal moving along a neuron. The space between neurons is called synapse. A stimulus is any factor in the environment that influences behavior. A response is a reaction to a condition or stimulus. An organism must be able to respond to a stimulus in order to survive. Reaction time is the length of time between application of a stimulus and detection of a response. PY Did you know that your brain works round the clock for as long as you O live? Your brain does not only control your thoughts, emotions, and movements but also numerous things that you are less aware of such as your breathing, your heartbeat, and even the stress that you feel. C How does your nervous system work? This system is like a network that relays messages back and forth from the brain to various parts of the body. It transmits information through the spinal cord, which extends from D the brain down through the back and consists of fine nerves that branch out to every organ and body part. When a message reaches the brain from any E part of the body, the brain commands the body to respond. You can think of your nervous system as a relay team where one runner passes the object to another runner. Relatively, you have nerve cells handing its information to the EP next cell, which passes the information to another cell. Finally, the information reaches into its destination and a reaction takes place. For instance, if you hold a rose stem and accidentally prick your fingers, the nerves in your skin release a message of pain to your brain. Your brain, in response to the signal, D commands the muscles in your hand to pull away. This split second relay inside your body happens in a much shorter period than it took you to read about it. Neurons are specially intended for information processing and signaling. They relay and receive messages (impulse) between the brain and body, and within the brain and spinal cord. Motor neurons transmit impulses from the brain to muscles, glands, or other neurons in the Peripheral Nervous System (PNS).Sensory neurons transmit impulses from sensory nerves (receptor cells) to the Central Nervous System (CNS). 236 All rights reserved. No part of this material may be reproduced or transmitted in any form or by any means - electronic or mechanical including photocopying – without written permission from the DepEd Central Office. First Edition, 2015.  Do the next activity to understand how the nervous system controls body processes. Activity 3 A Nervous Trip Objective: Explain how the body processes are controlled through the nervous system Procedure: 1. Form a team of 8 to 10 students and compete with the other groups in PY your class. 2. Among the members of the group, assign students who will represent the following parts: Brain, Organ, Sensory Neurons, and Motor Neurons O 3. Have the “Brain” stand at one end of the classroom, and the “Organ” at the other end near the blackboard. C 4. Let three to four members representing “Sensory Neurons” stand and line up between the “Brain” and the “Organ.” Another set of three to four members representing “Motor Neurons” will stand and line up facing the “Sensory Neurons.” D 5. Refer to the following illustration to see how you will position yourselves in the game. E EP D 237 All rights reserved. No part of this material may be reproduced or transmitted in any form or by any means - electronic or mechanical including photocopying – without written permission from the DepEd Central Office. First Edition, 2015.  Blackboard Legend: Sensory Neurons Student Organ Brain PY Motor Neurons O Figure 5. The game setup showing the relay course from start to end 6. Your teacher will show a card to the first member of the group, who is C the “Organ.” Each card will depict a situation of a stimulus affecting an organ. 7. The “Organ” must pass the message to one “Sensory Neuron” by D whispering. E 8. Each member who receives the message must relay it to another until it reaches the last “Sensory Neuron.” EP 9. Let the last person in the “Sensory Neuron” group run to the “Brain” to communicate the message that was transmitted from the “Organ.” 10. The “Brain” must think of a reaction to the stimulus presented and D pass this response to the “Motor Neurons.” 11. Each member of the “Motor Neuron” group who receives the response from the brain, must relay it to another until it reaches the last person in the group. 12. The “Organ” will receive this response through the “Motor Neurons” and run quickly to the board to write the response. 13. The team with the most acceptable answer and the shortest time of trip will win the game. 238 All rights reserved. No part of this material may be reproduced or transmitted in any form or by any means - electronic or mechanical including photocopying – without written permission from the DepEd Central Office. First Edition, 2015.  Guide Questions: Q8. How does the brain receive the information from the receptor? Q9. What does the brain do as soon as it receives the information? Q10. How is the message from the brain sent in response to the stimuli? Q11. How will you differentiate the sensory and motor neurons based on their functions? Q12. Based on the simulation activity, explain how information travels in the nervous system. PY Q13. Why does the damage in the nervous system cause paralysis of the body? Q14. What public health care programs in your locality are geared towards O dealing with health issues concerning the nervous system? KEY CONCEPTS: C When a receptor such as an organ perceives a stimulus, the impulse is sent to the brain by the sensory neurons, which then transmit D information from one nerve cell to another. As the message reaches the brain, it processes the information and commands an effector such as a muscle or an organ to respond. The message coming from the E brain is sent through the motor neurons. EP Suggested Enrichment Activities 1. During the first three years, a child’s brain triples in weight and D establishes approximately 1,000 trillion nerve connections. Thus, the child’s experiences during the first three years of life are crucial to brain development. Gather and write down information about the different ways of stimulating brain development in children. 2. Design a flyer that will disseminate information about the different diseases affecting the human nervous system. 239 All rights reserved. No part of this material may be reproduced or transmitted in any form or by any means - electronic or mechanical including photocopying – without written permission from the DepEd Central Office. First Edition, 2015.  Similar to the nervous system, the endocrine system controls and regulates body processes. Generally, the endocrine system is in control of the mechanisms in the body that slowly take place, such as cell growth. Rapid processes, such as body movement and breathing, are controlled by the nervous system. Although these two systems are different, they work together in a coordinate manner to enable the body to function properly. After studying about the nervous system, now you will learn about the endocrine system, its functions, and the glands that comprise the system. The Endocrine System PY Function of Endocrine System The endocrine system is composed of glands that secrete O different types of hormones that affect almost every cell, organ, and function of our body. It is essential in C regulating growth and development, metabolism, as well as reproductive processes and mood. D How does your endocrine system function? Endocrine glands secrete chemicals known as E hormones into the bloodstream, which carries them throughout the EP body. When a hormone in the blood reaches the target organ, it produces a notable effect. The endocrine system sends signals all over the body, much like the nervous system, D but unlike the instant responses activated by the nervous system, the effects can take a few hours or even Figure 6. The major endocrine organs in the body weeks. 240 All rights reserved. No part of this material may be reproduced or transmitted in any form or by any means - electronic or mechanical including photocopying – without written permission from the DepEd Central Office. First Edition, 2015.  Endocrine Glands and Their Hormones The endocrine system contains a group of glands that release hormones into the body. The following table lists all the major glands in the body, with their functions, locations, and the hormones they release. Gland Location Hormones Released Function Oxytocin, Vasopressin, Growth Hormone, Adrenocorticotropic stimulates growth, and at the base Pituitary Hormone (ACTH), controls the functions of of the brain PY Prolactin, Luteinizing other glands Hormone, Follicle Stimulating Hormone (FSH) regulates body O below the metabolism, and causes Thyroid Thyroxin, Calcitonin voice box storage of calcium in bones C controls the calcium Parathyroid in the neck Parathyromone levels in your body, and normalizes bone growth enables the body D in front of the Thymus Thymosin to produce certain heart antibodies E prepares the body for on top of the action, controls the Adrenal kidneys Adrenaline heart rate and EP breathing in times of emergency between the regulates blood sugar Pancreas Insulin, Glucagon kidneys levels D Reproductive lower Androgen, control maturation and -Testes abdomen Testosterone male characteristics (Males) influence female -Ovaries lower Estrogen, traits, and support (Females) abdomen Progesterone reproductive function 241 All rights reserved. No part of this material may be reproduced or transmitted in any form or by any means - electronic or mechanical including photocopying – without written permission from the DepEd Central Office. First Edition, 2015.  Now that you are familiar with the different glands in the human endocrine system, you can already perform the following activity. Activity 4 Who’s in Control? Objective: Identify the major endocrine glands in the human body and their functions Procedure: PY Study each picture that depicts the involvement of a particular gland in the endocrine system. Write down the name of the endocrine gland and explain its effect, according to its function. O Example C 1. 2. Thyroid Gland It regulates the metabolism of D the body. E Athletes burn up calories A pregnant woman A boy running away during exercise. from danger EP 3. 4. 5. D A kid growing taller A sick person in bed A girl eating sweets 242 All rights reserved. No part of this material may be reproduced or transmitted in any form or by any means - electronic or mechanical including photocopying – without written permission from the DepEd Central Office. First Edition, 2015.  Guide Questions: Q15. Which gland of the endocrine and nervous system controls the other glands in the body? Q16. How will you differentiate thyroid and parathyroid glands in terms of location and function? Q17. If a person’s blood sugar level becomes unstable, what glands might be involved in the problem? Q18. How important is the thymus gland in keeping your body free from PY diseases? Q19. What might happen to a person born without a thymus gland? Q20. How will you explain the sudden boost of energy, increased strength O and extraordinary ability to lift very heavy objects especially during emergency situations? C Q21. Why is injecting insulin an essential part of the daily regime for most people with diabetes? D Q22. Why does the menstrual cycle stop during menopause? E Q23. How do oral contraceptives, specifically birth control pills, prevent pregnancy? EP Q24. Breastfeeding releases oxytocin and prolactin, hormones that relax the mother and make her feel more nurturing toward her baby. On the other hand, how does the baby benefit from the production of these hormones D in the mother’s body? KEY CONCEPTS: The endocrine system consists of glands that secrete chemicals called hormones to control various body processes. This control system usually brings about slow changes in the body because chemical messengers move more slowly than nerve impulses. The major glands in the body are the pituitary, thyroid, parathyroid, thymus, adrenal, pancreas, ovaries, and testes. 243 All rights reserved. No part of this material may be reproduced or transmitted in any form or by any means - electronic or mechanical including photocopying – without written permission from the DepEd Central Office. First Edition, 2015.  Effects of Hormones in the Body Several processes in the body are coordinated by hormones which regulate and balance the working of organs, tissues, and cells. The endocrine system influences how your heart beats, how your bones and tissues develop, and even your capacity to have a baby. It plays an essential role in the occurrence of disorders such as diabetes, thyroid disease, growth disorders, and/or sexual dysfunction. Both men and women produce hormones in the same areas with one exception, the reproductive glands. Additional male hormones are produced in the testes while female hormones are produced in the ovaries. PY Some hormones have short-term effects while other hormones have long-term effects such as those that control our growth and the changes at the onset of puberty. During puberty, there are many hormonal changes that happen in your body. One moment you laugh, and then suddenly you feel like crying. Sudden mood swings are relatively caused by the increasing amount O of hormones in the body at this stage. It is therefore important to maintain a positive outlook in life and remember that these changes are only temporary and will stabilize with time. C Hormones act in very small amounts. If the organ and hormones do not produce the regulated amount of chemicals to your body, it may result in an abnormality of your body. This condition is called hormonal imbalance. An D increase or decrease in its amount may have a significant effect in the human body. E EP D Figure 7. Disorders due to endocrine dysfunction The next activity will get you acquainted with the different disorders in the endocrine system due to hormonal imbalance and the hormones responsible for them. 244 All rights reserved. No part of this material may be reproduced or transmitted in any form or by any means - electronic or mechanical including photocopying – without written permission from the DepEd Central Office. First Edition, 2015.  Activity 5 What Went Wrong? Objective: Explain the effect of a particular hormone in the body if not properly regulated Procedure: A. Identify which gland in the endocrine system is involved in each dysfunction and explain the effect of hormonal imbalance that was observed. PY O C E D EP D 245 All rights reserved. No part of this material may be reproduced or transmitted in any form or by any means - electronic or mechanical including photocopying – without written permission from the DepEd Central Office. First Edition, 2015.  PY B. Write a one-paragraph essay about how one of these conditions will affect your life if you have dysfuntion due to the effect of hormonal imbalance Guide Questions: O Q25. What condition may arise if the pituitary gland is not producing enough growth hormones? C Q26. What will happen to a person with excessive secretion of growth hormones from the pituitary gland? D Q27. Why is there a noticeable swelling in the front part of the neck of a person who has goiter? E Q28. How does using iodized salt help in preventing thyroid problems? EP Q29. How does the medical condition of a person with endocrine dysfunction affect his or her way of life? D KEY CONCEPTS: Hormones affect various processes in the body as they regulate and balance the functioning of organs, tissues, and cells. Hormones have great impact on your growth, appearance, emotions, and reproductive functions. These determine whether or not you develop disorders such as diabetes, thyroid disease, growth disorders, or sexual dysfunction. Hormones act in very small amounts. An increase or decrease in hormonal levels may result in body disorder due to hormonal imbalance. 246 All rights reserved. No part of this material may be reproduced or transmitted in any form or by any means - electronic or mechanical including photocopying – without written permission from the DepEd Central Office. First Edition, 2015.  For most living creatures, reproduction is basically a normal process controlled by hormones. Even though human reproduction is also controlled by hormones, the process is rather more complicated. Unlike other organisms such as plants and animals, you can make decisions about reproduction. What influence these decisions are your values, emotions, expectations, and goals. However, like any other living things, humans depend on reproduction for the survival of the species. If people stop to reproduce, the human species would become extinct. The Reproductive System The system involved in sexual reproduction is called the reproductive system. There is a striking difference between the male and the female PY reproductive systems, although they also share a number of similarities. For example, the reproductive organs of the male and female are developed from the same embryological structures, and some hormones are commonly found in both male and female, in varying quantities and produce different responses O The Male Reproductive System C E D EP Figure 8. Parts of the Male Reproductive System D Examine the diagram of the male reproductive system. Figure 8 shows the main parts of the male reproductive system. The cross-sectional side view of the reproductive system shows that certain parts of the male reproductive system are also part of the excretory system. 247 All rights reserved. No part of this material may be reproduced or transmitted in any form or by any means - electronic or mechanical including photocopying – without written permission from the DepEd Central Office. First Edition, 2015.  Be familiar with the specific functions of each basic part using the table below: Part Function Testis Produces sperm cells Scrotum Sac of skin that holds the testis Penis Deposits sperms into the vagina during mating Vas deferens Carries sperm from testes to urethra (tube) Urethra Carries sperm and urine out of the body PY Glands Provide liquid in which sperm can swim a. seminal - Secretes a fluid that makes up most of the vesicle components of the semen b. prostate - Secretes a slightly alkaline milky fluid that is O gland discharged as part of the semen c. bulbourethral - Secretes a thick and clear mucus that lubricates gland and neutralizes the any trace of acidic urine in the urethra C The Female Reproductive System D The female reproductive system has the following functions: E 1. Produces female sex cells EP 2. Receives sperm cells from the male 3. Nurtures the development of and provides nourishment for the new individual Examine the diagram on Figure 9 which shows the front view of the D female reproductive system. The female reproductive system consists of the ovaries, oviducts (Fallopian tubes), uterus, vagina, and external genitalia. The internal reproductive organs of the female are located within the pelvis, between the urinary bladder and rectum. The uterus and the vagina are in the middle part, with an ovary on each side of the uterus. 248 All rights reserved. No part of this material may be reproduced or transmitted in any form or by any means - electronic or mechanical including photocopying – without written permission from the DepEd Central Office. First Edition, 2015.  Vaginal Canal PY Figure 9. Parts of the Female Reproductive System O Now, study the function of each part. Part Function C Ovary produces egg cells serves as passageway of eggs from the ovary to the D Oviduct uterus; site of egg fertilization E serves as site of egg implantation; is where the Uterus fertilized egg develops EP Vagina receives the penis of male during mating Puberty involves the onset of sexual maturity and the ability to reproduce. D When a female reaches puberty, egg cells start to develop in her ovaries that produce the sex cells. It is also the time when the body develops the capacity to conceive. 249 All rights reserved. No part of this material may be reproduced or transmitted in any form or by any means - electronic or mechanical including photocopying – without written permission from the DepEd Central Office. First Edition, 2015.  The Role of Hormones in Female and Male Reproductive Systems The male reproductive system also has prostate glands. Chemicals from these glands nourish the sperm cells and help them mature. The production of sperm cells and the release of semen can be regulated by hormones or special chemicals that PY come from the testis, the brain and the pituitary gland (refer to Figure 10A). These hormones keep the reproductive system properly functioning. O Figure 10A. Pituitary gland controls the function of the testes. C The female reproductive system, just like the male reproductive system, is D also regulated by hormones. The follicles produce hormones that control the growth and release of eggs from the ovaries. E While other hormones prepare the uterus so a baby can grow in it, other hormones EP still control the stretching of the uterus during pregnancy. D Figure 10B. Pituitary gland controls the function of the ovaries. KEY CONCEPTS: Hormones play an important role in both male and female reproductive systems. The pituitary gland controls the functions of both the testes and the ovaries. These hormones keep the reproductive system properly functioning. 250 All rights reserved. No part of this material may be reproduced or transmitted in any form or by any means - electronic or mechanical including photocopying – without written permission from the DepEd Central Office. First Edition, 2015.  Feedback Mechanisms Involved in Regulating Processes in the Female Reproductive System The Menstrual Cycle We have learned that, on average, an ovary releases only one egg every 28 days. Now, what controls this timing? Hormones control many of the changes in the reproductive system. Remember that hormones are chemicals that affect certain body organs. The monthly changes that take place in the female reproductive system are called menstruation. This cycle occurs every month from the first onset which could happen when a female is between 10 to 13 years old. The monthly cycle continues for about 40 years. Refer to Figure PY 11 for a clearer explanation of the different events that take place in the cycle. Just follow numbers 1-10 in proper order. O C E D EP D Figure 11. The menstrual cycle To summarize, the important events during the menstrual cycle are as follows: 1. The pituitary gland controls and starts the cycle. 2. The pituitary gland releases hormones that cause the egg in the ovary to mature. The luteinizing hormone (LH) initiates the maturation of the follicles, converts ruptured follicles into corpus luteum and causes the secretion of progesterone. The follicle stimulating hormone (FSH) assists in the maturation of the follicles and causes the secretion of estrogen from the follicles. 251 All rights reserved. No part of this material may be reproduced or transmitted in any form or by any means - electronic or mechanical including photocopying – without written permission from the DepEd Central Office. First Edition, 2015.  3. Meanwhile, the ovary itself releases a hormone called estrogen, which causes the uterine lining to increase in thickness. The uterine lining becomes thicker so that the fertilized egg can attach to it. 4. The ovary releases an egg on day 14. Assume that no sperm is present. 5. The egg moves through the oviduct and enters the uterus. 6. Meanwhile the uterine lining continues to thicken. 7. The egg has not been fertilized, therefore, it will not attach to the uterus. 8. The thick uterine lining is no longer necessary, so the cells of the thickened uterine lining break off and leave the vagina. The unfertilized egg is lost and some blood is lost too. This loss of cells from the uterine lining, blood, and egg is called menstruation. 9. After menstruation, the cycle starts again. PY Did you know that menstrual cramps are the results of the strong contractions of the uterine wall that occur before and during menstruation? The cramps can be caused by excessive secretion of prostaglandins. Shedding of the endometrium of the uterus results in the inflammation in the endometrial O layer of the uterus and prostaglandins are produced as a consequence of the inflammation. C As you perform Activity 6, you’ll be able to understand the feedback mechanisms in the female reproductive system. D Activity 6 Mark My Calendar! E Objective: Describe the feedback mechanisms involved in regulating processes in the female reproductive system EP Materials: 2 calendar charts diagrams of the male and female reproductive system scissors D tape or glue Procedure: Part A - For no fertilization: 1. Get a calendar, with an approximate size of 8 x 11 inches. It must be marked by the day-to-day changes in the menstrual cycle. 2. Note that certain events are marked on certain days. 252 All rights reserved. No part of this material may be reproduced or transmitted in any form or by any means - electronic or mechanical including photocopying – without written permission from the DepEd Central Office. First Edition, 2015.  3. Make a copy of the diagrams of the menstrual cycle like in Figure 12. Some of the diagrams will show events in the ovary, and some will show events in the uterus. They are not in proper order. Cut out each square. PY Figure 12. Unsequenced events in the menstrual cycle 4. Place the diagram in the space to the right of the corresponding description. 5. Tape or glue your diagrams in right places/dates where they occur. O 6. Make sure that they are correctly placed. Part B – With fertilization of the egg C 1. Get another calendar marked by the day-to-day changes in the menstrual cycle. 2. You will be given a set of diagrams to place on the calendar. The diagrams will D not be in proper order. You may not need all the diagrams that show the uterus. E Guide Questions: Q30. How long does a regular menstrual cycle last? EP Q31. Describe what happens to an egg during the first 14 days of the cycle in Part A. D Q32. Describe what happens to the egg if fertilization occurs. Q33. Explain what takes place in the uterus after fertilization. Q34. Why is it important to study the menstrual cycle? 253 All rights reserved. No part of this material may be reproduced or transmitted in any form or by any means - electronic or mechanical including photocopying – without written permission from the DepEd Central Office. First Edition, 2015.  A feedback mechanism is the process through which the level of one substance influences the level of another substance. A negative feedback affects the production of hormones in the menstrual cycle. High levels of one hormone may inhibit the production of another hormone. PY O C D Figure 13. Negative feedback mechanisms in the menstrual cycle Feedback mechanisms in menstrual cycle: E 1. Follicle stimulating hormone (FSH) stimulates the ovaries to release estrogen. High levels of estrogen then prevent the further production of EP FSH. 2. Estrogen also stimulates the release of luteinizing hormone (LH) from D the pituitary gland, which in turn controls the production of progesterone. High levels of progesterone then inhibit the further release of LH. 254 All rights reserved. No part of this material may be reproduced or transmitted in any form or by any means - electronic or mechanical including photocopying – without written permission from the DepEd Central Office. First Edition, 2015.  Nervous System Working Together with Endocrine System to Maintain Homeostasis Both the nervous system and endocrine system are important in enabling the body to maintain homeostasis. Homeostasis is the state reached when each part of the body functions in equilibrium with other parts. This is attained through the regulation of the bodily functions by the endocrine and nervous systems. Most body systems maintain homeostasis by using feedback mechanisms. When the brain receives messages from the body about an internal change in one of its systems, it works to restore the system to its normal state. The levels of hormones in the body are controlled by feedback. It is important that the PY amount of hormones in our body is kept at the right level. The endocrine system plays an important part in homeostasis. To achieve homeostasis, the nervous and endocrine systems maintain a normal range of the following variables: Body temperature Amount of water in the body O Amount of metabolic wastes in the cell Blood calcium level Hormones in the blood C Q35. What might happen to a person whose nervous and endocrine systems fail to maintain homeostasis? D Q36. Suppose a boy skipped his lunch for the day. How will the hormones (glucagon) from his pancreas help his body to cope when his blood sugar E level drops below normal? EP Q37. Suppose a girl ate too many sweets such as candies and chocolates. How will the hormones (insulin) from her pancreas help her body cope with a possible blood sugar level rise above normal? Q38. How do the nervous and endocrine systems respond to an increase in D environmental temperature to achieve homeostasis? Q39. How do the nervous, endocrine, and reproductive systems perform their coordinated functions in various functions such as pregnancy and childbirth, menstrual cycle, breastfeeding, and sexual intercourse? 255 All rights reserved. No part of this material may be reproduced or transmitted in any form or by any means - electronic or mechanical including photocopying – without written permission from the DepEd Central Office. First Edition, 2015.  Performance Task: Video Making Topic: Contraceptive Measures Goal: Your objective is to present information to the public about the common and effective contraceptive measures used in family planning, in line with the Reproductive Health Law. The video that you will create must be in persuasive form. The challenge is how you will be able to convince people about the benefits of various contraceptive measures using gathered facts and scientific evidences. Role: Assume the role of a professional video production team. You are tasked PY to produce a promotional video that will be used in campaign advertising about various contraceptive measures used in family planning. Audience: Your voice, as part of the youth, will be heard through your campaign O advertising. You will present the finished video in front of your class. After that, you may also opt to use social media advertising to let other people view your multimedia presentation. It is important to clearly communicate your purpose from the beginning of the video. C Situation: Campaign advertising is often accomplished by combining a short message with a catchy tune that people are likely to remember. Since one of the D most powerful means of communicating information today is through music, you may persuasively share your thoughts and ideas on the topic using a chosen E melody. After studying the coordinated functions of the reproductive, endocrine, and nervous systems, you will be able to use scientific and logical explanations in promoting various contraceptive measures. There are challenges to overcome EP in accomplishing the task such as the conflicting judgments of people on the issue that may cause various controversies. Therefore, it is important to be objective in presenting ideas rather than being subjective. D Product/Performance: Produce a campaign advertising video that presents common and effective contraceptive measures used in family planning. The maximum video duration is three (3) minutes. You may seek assistance from your teacher in MAPEH regarding the tune, rhythm and beats of the music. For the rhyme and wordplay to be used, you may consult your teacher in English. Standards: You will be given two (2) days to conceptualize and execute your ideas through video-making. Once the video is finished, you may already present it in front of the class for evaluation. Your multimedia presentation will be assessed according to the rubric that will be given to you by your teacher. 256 All rights reserved. No part of this material may be reproduced or transmitted in any form or by any means - electronic or mechanical including photocopying – without written permission from the DepEd Central Office. First Edition, 2015.  V. Summary/Synthesis/Feedback The nervous system is composed of cells, tissues, and organs that regulate the body’s responses to internal and external stimuli. Each component of the nervous system has a specific role to do as an important part of a team. The nervous system has two main divisions, which are the Central Nervous System (CNS) and the Peripheral Nervous System (PNS). The Central Nervous System (CNS) serves as the main “processing center” for the entire nervous system. It has two main parts, which are the brain, and PY the spinal cord. The Peripheral Nervous System (PNS) contains all nerves that extend outside the brain and spinal cord. It has two main divisions, which are O the Somatic Nervous System and the Autonomic Nervous System. The basic unit of the nervous system is the nerve cell. Nerve cells are called C neurons. Neurons have dendrites and axons that aid in transmitting message. Neurons have the special ability to carry signals or impulses. A nerve impulse is an electrochemical gradient moving along a neuron. The space between D neurons is called synapse. A stimulus is any factor in the environment that may induce a nerve impulse that initiates physiological and behavioural changes. A response is a reaction to a condition or stimulus. To survive, an E organism must be able to respond to a stimulus. Reaction time is the length of time between application of a stimulus and detection of a response. EP When a receptor such as an organ perceives a stimulus, the impulse is sent to the brain by the sensory neurons, transmitting information from one nerve cell to another. As the message reaches the brain, it processes the information and commands an effector such as a muscle or an organ to respond. The D message coming from the brain is sent through the motor neurons. The Endocrine System consists of glands that secrete chemicals called hormones which control various body processes. This control system usually brings about slow changes in the body because chemical messengers move more slowly than nerve impulses. The major glands in the body are the pituitary, thyroid, parathyroid, thymus, adrenal, pancreas, ovaries and testis. 257 All rights reserved. No part of this material may be reproduced or transmitted in any form or by any means - electronic or mechanical including photocopying – without written permission from the DepEd Central Office. First Edition, 2015.  Hormones affect various processes in the body as they regulate and balance the functioning of organs, tissues, and cells. Hormones greatly influence growth, appearance, emotions, and reproductive functions. These chemicals play an essential role in the occurrence of disorders such as diabetes, thyroid disease, growth and/or sexual dysfunction. Hormones act in very small amounts. An increase or decrease in the said amount may result in a body disorder due to hormonal imbalance. The Reproductive System is a collection of organs in an organism that function together for sexual reproduction. The male reproductive organs are the penis, the testicles, the epididymis, the vas deferens, and the prostate gland. The female reproductive organs are the vagina, uterus (womb), Fallopian tubes, PY and ovaries. Hormones play an important role in both male and female reproductive systems. The pituitary gland controls the functions of both the testes and the ovaries. These hormones keep the reproductive system properly functioning. O Hormones secreted by the ovaries and a small gland in the brain called the pituitary gland control the menstrual cycle. C Feedback mechanism is the process through which the level of one substance influences the level of another substance. A negative feedback affects the production of hormones in the menstrual cycle. High levels of one hormone D may inhibit the production of another hormone. Homeostasis is the state reached when each part of the body functions in E equilibrium with other parts. This is attained through the regulation of the bodily functions by the endocrine and nervous systems. EP D 258 All rights reserved. No part of this material may be reproduced or transmitted in any form or by any means - electronic or mechanical including photocopying – without written permission from the DepEd Central Office. First Edition, 2015.  VI. Summative Assessment I. Answer briefly the following questions. (2 pts. each) 1. How does the Central Nervous System (CNS) function similarly to the Central Processing Unit (CPU) of a computer? _______________________________________________________ 2. Why are there significant changes in the body at puberty stage? _______________________________________________________ 3. In what way do the nervous and endocrine systems differ in the way they communicate messages throughout the body? ________________________________________________________ PY 4. Why is it important to maintain homeostasis in the body? ________________________________________________________ II. Match each gland in column A with its corresponding function in column B. (1 pt. each) O A B a. Stimulates growth, and controls the functions of 1. Thymus other glands C b. Controls the calcium levels in your body, and 2. Pancreas normalizes bone growth D c. Regulates body metabolism, and causes storage 3. Adrenal of calcium in bones d. Enables the body to produce certain antibodies 4. Thyroid E e. Prepares the body for action, and controls the 5. Parathyroid heart rate and breathing in times of emergency EP f. Controls maturation and male characteristics 6. Pituitary g. Regulates blood sugar levels 7. Testis h. Influence female traits and support reproductive 8. Ovaries D function III. Draw and label the parts of a neuron. (4 pts.) 259 All rights reserved. No part of this material may be reproduced or transmitted in any form or by any means - electronic or mechanical including photocopying – without written permission from the DepEd Central Office. First Edition, 2015.  Glossary of Terms Axon the part of the neuron that transmits impulses away from the cell body Dendrite the branchlike structure of the neuron that extends from the cell body to receive an impulse Embryo an organism in its early stages of development, especially before it has reached a distinctively recognizable form Endocrine Gland an organ that produces chemical secretions released PY directly into the bloodstream Egg Cell also called ovum (plural: ova); the female gamete Fertilization O a process that occurs when the sperm and egg combine