j. Co-ordination & Response 10/12/10 10:18 AM

Section 2: Structure and functions in living organismsj) Co-Ordination & reponse - humans

2.77 understand that organisms are able to respond to changes in their environment

2.78 understand that homeostasis is the maintenance of a constant internal environment and that body water content and body temperature are both examples of homeostasis

2.79 understand that a coordinated response requires a stimulus, a receptor and an effector.

2.83 describe how responses can be controlled by nervous or by hormonal communication and understand the differences between the two systems

2.84 recall that the central nervous system consists of the brain and spinal cord and is linked to sense organs by nerves

2.85 understand that stimulation of receptors in the sense organs sends electrical impulses along nerves into and out of the central nervous system, resulting in rapid responses

2.86 describe the structure and functioning of a simple reflex arc illustrated by the withdrawal of a finger from a hot object

2.87 describe the structure and function of the eye as a receptor

2.88 understand the function of the eye in focusing near and distant objects, and in responding to changes in light intensity

2.89 describe the role of the skin in temperature regulation, with reference to sweating, vasoconstriction and vasodilation

2.90 understand the sources, roles and effects of the following hormones: ADH, adrenaline, insulin, testosterone, progesterone and oestrogen.

2.77 Responding to Change 10/12/10 10:18 AM

2.77 Understand that organism are able to respond to changes in their external and internal environment.

Reference:Pg. 92 9.1 “Organisms detect chances around them”

To do: Discuss the changes that occur in the external environment which affect humans. Discuss the changes that occur in the internal environment of humans. Make a list of changes in the external and internal environment humans respond to.Answer the question at the end of the page.

Stimuli from the external environment that humans respond to:••Stimuli from the internal environment that humans respond to:••

QuestionThe bar chart shows the number of touch receptors in different areas of the skin.

Explain which area of the skin is likely to be the most sensitive. (2)What is the value of pain receptors in the skin? (2)

2.78 Homeostasis 10/12/10 10:18 AM

2.78 understand that homeostasis is the maintenance of a constant internal environment and that body water content and body temperature are both examples of homeostasis

Reference:Pg. 106 10.1 “Homeostasis keeps the internal environment constant”.

To do: Discuss the meaning of the term “homeostasis”. Give a definition for homeostasis Complete the table on homeostasis of water content and temperature.Answer the questions at the end of the page.

Definition of Homeostasis:

Examples of HomeostasisExample of Homeostasis

Organs of Monitoring

Organs which help maintain homeostasis

Water ContentBody Temperature

Questions

1. The kidneys are part of the body’s homeostatic mechanism.(a) Define homeostasis. (2)

(b) Outline the role of the kidneys in homeostasis. (2)

(c) Name another organ of the body also involved with homeostasis and outline its role. (3)

2. The table gives information about urine and sweat produced by a person on two different days. On one day the weather was cold and on the other it was hot. The person did the same amount of exercise, and ate and drank the same, on each day.

The person sweats more on the hot day.(a) Why is this helpful? (1)

(b) Why is the volume of urine lower on the hot day? (1)

(c) The person took in the same amount of salt in food and drink on both days. Why is the salt concentration of the urine higher on the hot day? (1)

(d) Give one other way by which a large amount of water is lost from the human body each day. (1)

3. Each week an athlete trains on 5 days (training days) but does not train on the other 2 days (rest days). The table shows how water losses from the athlete’s body are different on a rest day from those on a training day.

(a) Complete the table to show the total volume of water lost by an athlete on a training day. (1)

(b) Explain why the athlete sweats more on a training day. (2)

(c) On a training day the athlete needs to take in more water. Explain why the athlete needs to take in more water on a training day. (2)

2.79 Co-Ordination & Response 10/12/10 10:18 AM

2.79 Understand that a co-ordinated response requires a stimulus, a receptor and an effector.

Reference:Pg. 92 9.1 “Organisms detect changes around them”.Pg. 95 9.7 “Effectors respond when the body is stimulated”.

To do: Discuss the role of stimuli, receptors and effectors in the human body Jot down some notes on what is meant by a stimulus, receptor, effector and a sense organ. Complete the table on stimuli, receptors and sense organs.Answer the questions at the end of the page.

NotesStimulus

Receptor

Effector

Sense Organs

Stimuli Receptor Sense OrganLight

SoundNose

ChemicalPressure, temperature

Questions1. In a reflex action, which term describes light, temperature and chemicals? (1)A effectors B impulses C receptors D stimuli

2. List A gives the names of four stimuli. List B gives four parts of the human body.Draw a straight line from each stimulus in List A to the part of the body in List B which has receptors for that stimulus. (3)(One has been done for you.)

3. Complete the following sentence by choosing the correct words from the box.

To make us aware of a stimulus, impulses are sent along a .......................................... neurone to the .......................................... . (2)

4. The drawing shows a cape fox.

The cape fox has receptors which are sensitive to changes in the environment.(a) Write down one part of the cape fox’s body where there are: (3)receptors that are sensitive to light.receptors which help it to keep its balance.receptors which are sensitive to chemicals.

(b) The cape fox lives in a hot desert.Write down one way in which the cape fox is adapted for losing heat. (1)

5. The drawing shows a tennis player. The player uses different receptors during a tennis match.Match statements, A, B, C and D, with the labels 1– 4 on the drawing. (2)A contains receptors that help him to feel the racketB contains receptors that help him to see the ballC contains receptors that help him to keep his balanceD contains receptors that help him to smell the grass on the court

6. Humans have a number of senses, for example touch. Senses are detected by receptors, for example skin detects touch. In the boxes write the names of four other senses. By each box write the name of the receptor. (8)

7. A man is walking along a street. He plans to cross the road at the pelican crossing. Pelican crossings show a flashing green person and bleep when it is safe to cross.

State two different ways the man uses:(a) his eyes, to help him cross the road safely; (2)

1 2

(b) his ears, to help him cross the road safely. (2)1 2

(c) Eyes, ears and skin contain sense receptors.State the names of two other parts of the body which contain sense receptors.(2) 1

2

(d) What type of sense receptor is in the skin of his feet? (1)

8. Fill in the table about receptors. The first answer has been done for you. (3)

9. Humans use receptors to help them to respond to stimuli in the environment. Match up each receptor with the correct sense. One has been done for you.(5)

RECEPTORS IN THE SENSITIVE TOEyes LightSkin

SoundTongue

10. The drawing shows an aardvark.

The aardvark has receptors which are sensitive to changes in the environment. (a) Name one part of the aardvark’s body where there are: (3)

receptors which are sensitive to light;receptors which help it to keep its balance;receptors which are sensitive to chemicals.

(b) The aardvark feeds mainly at night. It is hunted by several predators.Use information from the drawing to give one feature of the aardvark which is an adaptation for sensing predators at night. (1)

11. Complete the following sentence by choosing the correct words from the box. (2)

To make us aware of a stimulus, impulses are sent along a ………………………………………………………… neurone to the ……………………………………………………….

brain glands motor sensory

2.83 Nervous vs hormonal 10/12/10 10:18 AM

2.83 describe how responses can be controlled by nervous or by hormonal communication and understand the differences between the two systems

Reference:Pg. 95 9.8 “Hormones and nerves allow communication”.Pg. 101 Table 9.2 “A comparison of the nervous and endocrine systems in a mammal”.

To do: Discuss the differences between nervous and hormonal control Jot down some notes on your discussion Complete the table comparing nervous and hormonal communicationAnswer the questions at the end of the page.

Notes

Comparison of Nervous and Hormonal CommunicationNervous Endocrine

(hormonal)Composed of:TransmissionSpeed Duration of Effect

Questions1. Complete the table to show the differences between nervous and hormonal control in the body. (4)

Feature Nervous Control Hormonal ControlSpeed Extremely rapidPathway NeuronesNature of ‘impulse’ ChemicalOrigin Endocrine gland

2. The table gives some information about hormones. Which row in the table is correct? (1)

3. Hormones are sometimes used to regulate human reproduction.(a) What is a hormone? (1)

(b) How are hormones transported around the body? (1)

2.84 CNS 10/12/10 10:18 AM

2.84 recall that the central nervous system consists of the brain and spinal cord and is linked to sense organs by nerves

Reference:Pg. 96 “Most animals have a central nervous system”.

To do: Discuss the components and functions of the CNS Jot down some notes on the CNS Label the diagram of the motor neurone Add notes on the structure and function of motor neurones

Notes on CNS

Use pg. 96 to help you label the motor neurone below.

Which three things are found in this motor neurone that would be found in all cells?

Which diagram shows a motor neurone? (1)

Notes on Structure and Function of Motor NeuroneDendrites

Cell Body

Axon

Axon Terminal/ Nerve Endings

Myelin Sheath

Node of Ranvier

2.85 Electrical Impulses 10/12/10 10:18 AM

2.85 Understand that stimulation of receptors in the sense organs sends electrical impulses along nerves into and out of the central nervous system, resulting in rapid responses.

References:Pg. 95 “Neurones carry nerve impulses”.Pg. 96 “Myelinated neurons carry impulses quickly”

To do: Discuss the sequence of events from a stimulus to a response Copy down the notes on the sequence.Summarise the sequence of events in a flow diagram

2.86 Reflex Arcs 10/12/10 10:18 AM

2.86 Describe the structure and functioning of a simple reflex arc illustrated by the withdrawal of a finger from a hot object.

Reference:Pg. 97 9.12 “Reflex arcs allow rapid response”.

Diagram 9.9 “A Reflex Arc”

To do:Demonstrate “knee jerk” activity.Explain “knee jerk” as an example of a reflex arc.Answer all questions

Reflex Arc “Knee Jerk” exampleIn a reflex arc the three types of neurones are arranged as shown in the diagram.

In a simple reflex arc, such as the knee jerk, a stimulus is detected by a receptor cell, which sends the message to the CNS via a sensory neurone. In the CNS a relay neurone (interneurone) passes the message to a motor neurone, which carries the nerve impulse out to an effector, such as a muscle, which responds by contracting.

Reflex arc can also be represented by a simple flow diagram:

Questions:

1. The diagram shows the structures involved in a reflex action.

What shows the sequence in which these structures become involved? (1)A P → Q → R → SB P → S → R → QC Q → R → S → PD Q → S → P → R

2. The diagram shows the parts of the nervous system which act when the hand touches a hot object.

(a) Which letter, A to D, shows: (3)the sensory neurone;the motor neurone;the receptor?

(b) What happens to muscle Y when impulses arrive at point X? (1)

(c) Moving the hand away from the hot object is a reflex action. What is a reflex action? (2)

3. The diagram shows a generalised reflex arc.

(a) Identify the three neurones labelled X, Y and Z. (3)

(b) Give an example of an effector. (1)

4. Complete and label the diagram below of a reflex arc. (3)

5. A person accidentally touches a drawing pin. Their hand automatically moves away from the pin. The diagram shows the parts involved in this reflex action. Questions a-d all refer to the diagram below.

(a) Which of the following shows the pathway of nerve impulses of this reflex?(1)1 R Q P T S2 S R Q P T3 S T P Q R4 T P Q R S

(b) Which row in the table shows the correct names of the neurones in the diagram? (1)

(c) For the structures in the diagram, which row in the table is correct? (1)

(d) How does information pass across a synapse? (1)1 by an electrical signal passing along a relay neurone2 by an impulse jumping across the gap3 by an impulse passing along a sensory neurone4 by movement of a chemical

6. The diagram shows the pathway of impulses in a reflex action. (2)

Match words, A, B, C and D, with the labels 1– 4 on the diagram.

A spinal cordB musclesC responseD stimulus

7. The diagram shows a reflex arc. Which label points to the sensory neurone?(1)

8 .What is the correct sequence of structures involved in a reflex action? (1)A. effector → sensory neurone → relay neurone → motor neurone → receptorB. effector → motor neurone → relay neurone → sensory neurone → receptorC. receptor → sensory neurone → relay neurone → motor neurone → effectorD. receptor → relay neurone → sensory neurone → motor neurone → effector

9. The diagram represents a reflex arc.

(a) Use the information in the diagram to help describe the nerve transmission involved in a named reflex arc. (6)

(b) Explain how reflex actions are of value to the body. (2)

(c) How does a reflex action differ from a voluntary action? (1)

10. The diagram shows a cross section of a spinal cord.

(a) On the diagram draw a reflex arc which includes an association neurone. Using arrows show the direction the nerve impulse would travel along the neurones. (2)

(b) On the diagram label the neurones you have drawn. (3)

11. Rapid withdrawal of a hand from a hot stove is an example of a reflex action. This response does not involve the brain.The diagram shows a section through the spinal cord with the sensory neurone completed.

(a) Complete the diagram to show the arrangement of the other two neurones in this reflex arc. (2)

(b) On the diagram, label the relay neurone. (1)

(c) What is the advantage of not involving the brain in the reflex action described above/ (1)

12. The diagram shows a reflex arc.

(a) What type of stimulus causes the reflex? (1)

(b) Name the effector in the reflex. (1)

(c) Explain how the brain becomes aware of the stimulus. (3)

13. The diagram shows the pathways of a reflex arc.

(a) Which letter represents the: (2)sensory neurone?relay neurone?

(b) Give an example of a reflex action. (1)

14. The diagram shows a reflex arc.

(a) Use the diagram to help describe the pathway of an impulse from the stimulus to the association (relay) neurone. (4)

(b) Describe the response when this impulse reaches the effector. (2)

2.87 The Eye 10/12/10 10:18 AM

2.87 Describe the structure and function of the eye as a receptor

Reference:Pg. 92 9.2 “The eye is well protected”.

9.3 “Cells in the retina are receptive to light”Diagram 9.1 “Section through a human eye”.

To do:The eye is a very complex structure.You need to be able to label it and describe the function of the different parts.Label the diagram “Simple Eye Structure”View the diagram “Detailed Eye Structure”Whiteboard activity (you can visit the site again later by yourself). http://www.eschoolonline.com/company/examples/eye/eyedissect.htmlEye dissection – you will need to listen carefully to names of structures and their functionsUsing the website: http://www.exploratorium.edu/learning_studio/cow_eye/index.htmland from the discussion during the dissection, complete the table on structure and function of eye.View the two websites below as a recap:http://www.bishopstopford.com/faculties/science/arthur/Eye%20Drag%20&%20Drop.swf

http://www.brhs.ab.ca/courses/biology30/bpages/HotPotatoes/ns_match_05_eye.htmTry to label the final diagram from memory without looking back through the notes

Diagram: Simple Eye StructureThe diagram below is a very basic diagram of the eye – it gets a lot more complicated!

Diagram: Detailed Eye Structure

Use your book or the internet to find out the functions of the different parts of the eye.A single statement for each is all you need.This website should help you out.http://www.exploratorium.edu/learning_studio/cow_eye/index.html

Structure FunctionConjunctivaCorneaPupilIrisAqueous humourCiliary MuscleSusensory LigamentScleraChoroidRetinaFoveaOptic nerveBlind spotVitreous Humour

Label this final diagram from memory without looking back through your notes.

A.

B.

C.

D.

E.

F.

G.

H.

2.87 Lens & Pupil Adjustment 10/12/10 10:18 AM

2.87 understand the function of the eye in focusing near and distant objects, and in responding to changes in light intensity

Reference:Pg. 93 9.4 “The eye focuses light”

9.5 “The lens adjusts the focusing”Diagram 9.2 “How an image is focused onto the retina”Diagram 9.3 “Focusing on a nearby object”.Diagram 9.4 “Focusing on a distant object”.

Pg. 94 Diagram 9.5 “How the shape of the lens is changed”.

Pg. 96 9.6 “The Iris adjusts how much light enters the eye”.

To do:Copy down notes from board.You will need your green books to draw and label diagrams to illustrate lens adjustment and pupil adjustmentComplete all questions

Notes

Questions1. The diagram shows an eye. The eye is focused on a near object.

The object is moved away from the eye but the image stays in focus on the retina.State what happens to the following parts of the eye as this happens.(a) Ciliary body (muscle) (1)

(b) Suspensory ligaments (1)

(c) Lens (1)

(d) The lens refracts (bends) light to a focus on the retina.Name one other part of the eye that refracts light. (1)

2. John went to the cinema.Diagram A shows his left eye before the lights were dimmed.

Diagram A

Diagram B shows the same eye after the lights were dimmed.

Diagram B(a) Label X and Y. (2)(b) Describe the change in X after the lights were dimmed. (1)

(c) Describe the change in Y after the lights were dimmed. (1)

(d) Why is it important for Y to change when lights are dimmed? (1)

3. The diagram shows a cross section of an eye.It shows light entering the eye from a distant object.The image is formed in front of the retina, showing short sight.

(a) Label parts A and B. (2)

(b) Explain how a person with good sight would focus an image of a near object on the light sensitive cells in the retina. (4)

4. The amount of light which reaches an eye changes the size of the pupil.Mike switches the light on in a dark room.These changes take place in his eye. They are not in the correct order.A muscles in the iris contract which makes the pupil smallB less light reaches the retinaC electrical impulses are sent to the iris from the brainD electrical impulses are sent through the optic nerve to the brainE light reaches the retinaF bright light enters his eyeWrite one letter in each box to show the correct order. (5)

number 1 2 3 4 5 6letter

A. B.

5. Diagrams A and B show sections through the front part of the eye.

Diagram A Diagram B(a) Which diagram, A or B, shows the lens when the eye is focused on a near object? Explain your answer. (2)

(b) Name another part of the eye which helps to focus an image on the retina.(1)

2.89 Temperature Regulation 10/12/10 10:18 AM

2.89 describe the role of the skin in temperature regulation, with reference to sweating, vasoconstriction and vasodilation.

Reference:Pg. 107 10.3 “Humans control their body temperature”. 10.4 “Human skin structure if related to function”. Diagram 10.2 “A section through human skin” Pg. 108 10.6 “The dermis has many functions” P.g 108 10.7 “The skin reacts when you are too cold” 10.8 “The skin reacts when you are too warm”

Diagram 10.3 “How the skin helps in temperature regulation”.Pg. 109 10.9 “Temperature regulation involves negative feedback”.

To do:Name the part of the brain that checks body temperature?

How does this part of the brain check body temperature?

Use the diagram below to discuss the function of the skin in relation to temperature regulation.Complete the table on the structure of skin in relation to its function in temperature regulation.

Complete the notes on Mechanisms to decrease/ increase heat lossComplete the questions

Use the diagram above and you discussion to complete the following table.

Structure Description/ FunctionEpidermis

Lower layer of the skin.Secrete sweat

SweatNerve endings

Helps to insulate the body from heat loss, acts as a food reserve, cells contain large drops of oil

Mechanism to Reduce Heat LossVasoconstriction

Mechanisms to Increase Heat LossVasodilation

Sweating

Questions1. How do sweat glands and blood vessels near the skin surface respond when body temperature rises above normal? (1)

2. The internal body temperature determines how much a person sweats. The graph shows the effect of different internal body temperatures on a person’s rate of energy loss by sweating.

(a) How much more energy was lost from the body each second by sweating when the body temperature was 37.6 ºC than when it was 36.6 ºC? Show clearly how you work out your final answer. (2)

(b) Explain why a person would feel more thirsty when the body temperature was 37.6 ºC than when it was 36.6 ºC. (2)

(c) Explain how sweating helps to control body temperature. (3)

3. Jim measured his body temperature during part of one day.

(a) At 10.15 Jim started to shiver. Explain how shivering caused the change in his body temperature over the next few minutes. (2)

(b) At 10.45 Jim was too hot.Name one process in Jim’s body that could bring down his temperature. (1)

(c) State how heat energy is lost from Jim’s body in this process. (1)

4. Humans can maintain a constant body temperature even in very hot or cold weather.(a) How does the brain receive information about the external temperature? (2)

(b) On a hot day the skin may appear more red, or flushed, than on a cold day. Describe the processes in the skin that bring about this change. (2)

5. A small mammal lives in a hot desert. It spends most of its time in a hole in the ground where the air is cooler. Each time the mammal leaves the hole, its body temperature rises.The graph shows changes in body temperature of this mammal during one day.

(a) What is the body temperature of the small mammal at 4 am? (1)

(b) When is the highest body temperature reached? (1)

(c) How many times did the small mammal leave the hole? (1)

(d) When the small mammal comes out of its hole, it sweats a lot.Why does the small mammal need to sweat? (1)

(e) How might too much sweating be a problem for the small mammal? (2)

6. Use words from the box to complete the sentences. (4)

decreases increases stays the same

On a hot day, sweat production ................................................... compared to a cold day but body temperature ..................................................... . On the same hot day, urine volume ................................................................. but urine concentration ............................................................ .

7. A person’s body temperature was measured and recorded over a 24 hour period.

(a) For how long was the person asleep? (1)

(b) What are the lowest and highest body temperatures recorded during the 24 hour period? (2)

lowest ............................. °Chighest ............................ °C

8. The diagram shows a sweat gland in the skin.

blood capillaries evaporates decreasesheat

rises salt sweat duct water

Use information in the diagram to help complete the passage. (6)Use words from the box to fill in the gaps.You may use each word once, more than once or not at all.The substances in sweat include ........................................................, urea and salt. These substances arrive at the sweat gland in the ...................................................... . The sweat goes up the ......................................... and lies on the surface of the skin. Here the water from the sweat .......................................... . This change from liquid to vapour needs ......................................... energy. This energy is supplied by the body, so body temperature ......................................... .

9. In an experiment, Sam was put in a room at 2 °C for thirty minutes and then in a room at 30 °C for thirty minutes.The graph shows how his body and his skin temperatures varied during this time.

The diagram shows some blood vessels in Sam’s skin.

The blood vessel labelled A can become wider or narrower.(a) Describe changes that took place in the width of blood vessel ‘A’ during the experiment. (1) (b) Explain how these changes helped Sam’s body maintain a constant body temperature. (3)

(c) Explain why maintaining a constant body temperature allows Sam’s cells to work effectively. (3)

10. The diagrams show sections through skin, on a hot day.

Explain how suntan cream may affect cooling by sweating. (3)

2.90 Hormones 10/12/10 10:18 AM

2.90 understand the sources, roles and effects of the following hormones: ADH, adrenaline, insulin, testosterone, progesterone and oestrogen.

Reference:Pg. 100 Table 9.2 “Mammalian endocrine glands and hormones”.

Diagram 9.13 “Some endocrine glands”.

ADHSource Targets Effects

AdrenalineReference:Pg. 101 9.19 “Adrenaline prepares the body for action”.Source Targets Effects

InsulinReference:Pg. 110 10.10 “Glucose is needed for respiration”.

10.11 “The pancreas secretes insulin and glucagon”10.12 “The liver changes the amount of glucose in the blood”

Pg. 111 Diagram 10.5 “How blood sugar is regulated”.Source Targets Effects

TestosteroneReference:Pg. 80 8.26 “Sexual maturity is reached at puberty”.

Pg. 101 9.20 “Male sex hormones”Source Targets Effects

Progesterone and OestrogenReference:Pg. 80 8.26 “Sexual maturity is reached at puberty”.

Pg. 101-102 9.21 “Female sex hormones control the menstrual cycle”

Diagram 9.14 “Hormones and the menstrual cycle”.

ProgesteroneSource Targets Effects

OestrogenSource Targets Effects