Multicellular. Organisms

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Mark Carr
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1 Multicellular Organisms Part 4 Maintaining Stable Body Conditions 1

2 Maintaining Stable Body Conditions LI To identify the parts of the Nervous System and their function LI To understand the mechanisms involved in a reflex arc LI To understand the function of the skin LI To explain how the body maintains a stable temperature LI To measure temperature using a thermometer LI To explain the function of the skin in maintaining stable body temperature LI To explain the purpose of sweating in maintaining stable body temperature LI To explain the problems of Diabetes in maintaining blood sugar level 2

3 The Nervous System LI To identify the parts and their function of the Nervous System Your nervous system controls your body. This system is made up of the brain, the spinal cord and nerves. What to do Stick The Nervous System into your notes and label the three parts of the nervous system. 1. Which two organs make up the Central Nervous System (CNS)? 2. Copy and complete the table below. Part Nerves Function Controls the whole body and co-ordinates all the nerve impulses Relays impulses between the nerves and the brain and also controls reflexes. Reflex Actions Some stimuli (a change to the external environment) cause extremely rapid responses which are so fast that the brain is not aware of the action until after it has occurred. Reflex Actions are involuntary and their function is for protection. Three types of nerves are responsible for this type of reflex action: The sensory nerve, relay nerve and motor nerve. 3

4 With a partner, you are going to carry out three simple activities on reflex actions. Write what you have observed for each activity. 1. Eye Response Collect a torch. Shine the beam into your partner s eyes. Describe any changes that you observe. 2. Heel Response Collect a rubber hammer. Get your partner to kneel on a stool, gently tap the leg above the heel. Alternatively, your partner could sit on a bench and gently tap just below the knee cap. Describe what happens. 3. Measuring reaction time using a computer Go to Follow the on screen instructions. Complete the following table for you and your partner s scores. Person Reaction Time (s) Average Reaction Time (s) a. What was your fastest reaction time? b. Does your time improve with practice? c. How do your results compare with your partners? If time permits, search for other tests on Reaction Time and have a go! 4

5 The Reflex Arc LI To understand the mechanisms involved in a reflex arc The reflex arc is an arrangement of nerve cells which allows the fastest possible reaction to a hazardous stimulus. What to do Stick your Reflex Arc diagram into your notes and label the appropriate parts. Copy and complete the following passage about reflex arcs. The sensory impulse is transmitted to the via a sensory from a sense organ, where it is relayed directly to a to transmit the impulse to the. The brain is made aware of the change a fraction of a second later to make any necessary adjustments of balance. Reflex actions are and from harm. 5

6 Copy and complete the following table to summarise where nerves in the reflex arc take impulses from and to. Type of Nerve Direction of Impulse (from to). Sensory Nerve Sensory nerve to motor nerve, through the spinal cord 6

The Skin LI To understand the function of the skin Your body is covered with skin. Skin is the largest organ in your body! What are the functions of the skin? Share your ideas with a partner.

7 The Skin LI To understand the function of the skin Your body is covered with skin. Skin is the largest organ in your body! What are the functions of the skin? Share your ideas with a partner. What to do Complete the Functions of Skin diagram and stick it into your notes. The Skin & Sensitivity It might surprise you to learn that your skin is as much of a sense organ as your eyes and ears. In fact, it contains millions of nerve endings and nerve cells which send information to the brain. These nerve endings and nerve cells do not lie on the surface of the skin. They are found in the living layer below the surface. (The outer layer of the skin is made of dead skin cells). Diagram of the skin: The skin contains receptor cells which detect heat, cold, touch, pressure and pain. 7

8 What to do Label your copy of The Skin diagram and stick into your notes. How Sensitive Are You? The skin is very sensitive to touch. Some areas of skin are more sensitive than others. Your teacher will show you how to carry out an experiment to find out which areas of skin are the most sensitive. 1. Copy the heading into your jotter. 2. Write an aim for this experiment. 3. Copy the following table for your results: Area of Skin Back of hand Forearm Elbow Palm of Hand Fingertip Smallest distance between points when you still felt two points (mm) 4. Which area of skin is least sensitive and which is most sensitive? 5. How would you improve the reliability of results? 8

9 Body Temperature & Health LI To explain how the body maintains a stable temperature Our body needs to be kept at a constant temperature between 36.0 C and 37.3 C. Our body temperature can vary slightly depending on when it is measured. The brain is the control centre for temperature. If our thermostat is working properly in the brain then our temperature should be within the normal range. Changes in temperature which fall out with the normal range are good indicators that something has gone wrong in the body. Doctors often take a patient s temperature. A body temperature above 40 C can indicate a fever caused by an infection or can indicate heatstroke. A body temperature below 35 C indicated hypothermia and if the body falls below 30 C, death can follow. (Babies and the elderly are especially at risk of hypothermia). Answer the following questions in sentences. 1. What is the normal range of body temperatures? 2. What might your temperature be if you had a fever? 3. If your body temperature was 32 C, what would you be suffering from? Normal body temperature is usually described as 37 C. 9

10 Temperature & Thermometers LI To measure temperature using a thermometer A thermometer is used for measuring temperature. Your teacher will show you a variety of thermometers and how to use them. Collect: Clinical Thermometer Liquid Crystal thermometer Digital thermometer What to do Use the thermometers to measure your body temperature under different conditions. 1. Copy the table below. Type of Thermometer Clinical Body Temperature ( C) In Class Outside After Exercise Liquid Crystal Digital 2. Does your body temperature stay the same in each condition? Explain your answer. 3. Parents often use a liquid crystal thermometer for babies. Explain why. 10

The Skin & Temperature Regulation LI To explain the function of the skin in maintaining stable body temperature The skin works together with the nervous system (nerves and brain) and the

11 The Skin & Temperature Regulation LI To explain the function of the skin in maintaining stable body temperature The skin works together with the nervous system (nerves and brain) and the cardiovascular system (heart and blood vessels) to regulate body temperature. Both the brain and the nerves in the skin monitor body temperature. What to do Collect: a show me board and pen. Work with a partner to write down all of the changes that happen to the body when we are too hot and when we are too cold. Following a class discussion, copy and complete the following table, using the phrase bank provided. Changes that happen in the body to regulate temperature WHEN TOO HOT (to increase heat loss) WHEN TOO COLD (to reduce heat loss) Phrase Bank: Increased sweating Hairs on the skin lay flat Decreased sweating Small blood vessels in the skin widen to carry more blood to the surface (we look flushed ) Hairs in the skin stand up ( goose bumps ) Small blood vessels in the skin become narrower to reduce blood flow to 1. the Complete surface (we your get Temperature cold hands and toes) Regulation diagram from your Shivering pack and stick it into your notes. 11

12 2. Write notes to explain the following: What to do Why sweating helps to cool us down. Why increased blood flow to the skin helps to cool us down. Why the hairs on our skin standing up helps to keep us warm. Why shivering helps to keep us warm. 3. Using class resources or the internet, find the answers to the following questions: What is the normal human body temperature? What does hypothermia mean? When might a person suffer from hypothermia? What does hyperthermia mean? Give two examples of when a person might suffer from hyperthermia. What happens to a person if their body temperature is too high or too low for a long period of time? 12

Investigating the Effects of Sweating LI To explain the purpose of sweating in maintaining stable body temperature You are going to investigate the effects of sweat on the rate at which a body loses

13 Investigating the Effects of Sweating LI To explain the purpose of sweating in maintaining stable body temperature You are going to investigate the effects of sweat on the rate at which a body loses heat by using a model of the body. 1. Complete an aim, method and copy the following results table for this experiment. Method: 2. Set up equipment, as shown in the diagram below. Fill the conical flask with hot water from a kettle and then wrap a dry sock around the flask. 3. Record the starting temperature of the water, and then start a stop clock. Record the temperature every minute for ten minutes. 4. Repeat the practical, using a sock which has been soaked under a running cold tap and then wrung out so that it was still damp. Body Model Sock Cotton wool Hot water 13

14 Results Table: Time (mins) Average Temperature (C) Dry Cloth Damp Cloth Plot a graph of your data Which flask cooled faster? How do you explain your results? Was your experiment valid if not, why not? What variables did you keep the same when using the dry sock and the wet sock? 14

15 Diabetes & Insulin LI To explain the problems of Diabetes in maintaining blood sugar level What to do How much do you already know? Get an A4 piece of paper and mark it like the one below. Discuss the following ideas in groups of 4. Each person in the group should choose one of the ideas 1-4 from the list below and write as much relevant information into the correct section as you can. Once you are finished, answer section 5 as a group. 1. What is Diabetes? 2. What is Insulin? 3. Where is insulin produced in the body? 4. What happens to a person who cannot produce their own insulin? 5. Write all of the information that you all agree on from sections 1-4 into section 5. 15

Causes of Diabetes Using the internet as your source, research some causes for diabetes.

16 Diabetes What to do Your teacher will show you a video clip on diabetes. Answer the questions on your The Effect of High Sugar Intake on Blood Sugar Levels diagram from your pack. Causes of Diabetes Using the internet as your source, research some causes for diabetes. Make sure that your notes include the following: At least three causes of diabetes. The types of diabetes that can occur. Which type of diabetes is most common in Scotland and why? Which type(s) of diabetes require insulin injections? Here are some websites to help you get started:

17 Menu for Diabetes Imagine you are organising the catering for a Diabetes convention. In pairs, construct a menu for the convention. Think about what sorts of foods you should avoid from the menu. What to do Write out your menu in a page of your jotter, like the one below: 17

18 Step Ahead: Find out about Negative Feedback Control. What does this mean? What conditions are controlled this way in the human body? Draw out a simple flow diagram to illustrate Negative Feedback Control with regards to either body temperature or blood glucose level. 18

Observing Nervous Responses

Lab #15H Observing Nervous Responses Introduction The nervous system is a series of conducting tissues that carries impulses to all parts of the body. Your nervous system initiates many types of reflex