Download - Coordination and Control
-
8/6/2019 Coordination and Control
1/47
1
Coordination and Control
Objectives:
1. State the main divisions of the nervous system2. distinguish between a neurone and a nerve3. define a reflex action4. explain the functions of motor and sensory neurons and spinal
snyapses
5. explain the process by which voluntary action occurs6. explain the response of sense organs to stimuli7. relate the internal structures of the eye to their functions8. explain how images are formed in the eye9. explain accommodation in the eye10.explain the causes of, and corrective measures of eye defects11.identify the sites of hormone production12.explain the roles of the various hormones in the human body13.distinguish between hormonal and nervous control systems14.define mental illness
-
8/6/2019 Coordination and Control
2/47
2
THE SENSES, NERVOUS SYSTEM, HORMOES AND CO-
ORDINATION
1. Sense Organs
Define Sense organs List the stimuli in which sense organs respond (light , sound, touch,
temperature and chemical changes)
2. The Eye
Structure and function Control of light entering the eye Formation of images Accommodation Common eye defects (long and short-sightedness, astigmatism)
3. The Nervous System
State the main divisions of the nervous system: Central NervousSystem (CNS) comprising brain and spinal chord and peripheral
nervous system (spinal nerve)
Distinguish between neuron and nerve Define a reflex action Structure of the spinal cord The spinal reflex action The knee jerk reflex
4. Hormones
Definition Endocrine and endocrine glands Location of the endocrine glands in the body Hormone produced by endocrine glands Function of each hormone Describe the control of blood sugar levels Describe the role of oestrogen progesterone in the menstrual cycle and
in pregnancy
distinguish between quick-acting hormones (insulin) and slow acting hormones (oestrogen) distinguish between the nervous control system
-
8/6/2019 Coordination and Control
3/47
3
Introduction
We are capable of observing and interacting with various stimuli which are
changes in the environment. I am sure that I am not the only one who puts
on a sweater when it gets really cold or squint my eye after moving from a
dimly lit room to the outside in the sun.
Our bodies are made up in such a way that we are able to detect the changes
that occur around us. These changes can be very obvious or subtle. For
example, our eyes pick up readily on the difference in the intensity of light
(squinting in sudden very bright light) and tiny organs in our skins called
receptors easily detect pressure intensity (the prick of a needle on the finger
as opposed to a soft cushion). This automatic response to changes in the
environment is called a reflex action
A reflex action may be described as a rapid automatic response to a
stimulus (change in the environment) by a muscle or a gland which doesnot require conscious control or a process of thinking. The stimuli
(change in theenvironment) may be good or bad for our bodies, which are
mainly determined by our brain which is a part of the central nervous
system. The Central Nervous System (CNS) causes our bodies to make
appropriate responses to changes in the environment. How our bodies
respond is for our own preservation and protection.
The processes that coordinate the bodys response to various
changes in the environment enable mans chances of survival.
Changes in the environment are detected by our bodiesOur bodies coordinate a response to a particular stimulus
(change in the environment)
The automatic response towards a stimulus is ultimatelyfor mans protection and survival.
With an understanding of this definition of a reflex action, can you see how
the following are examples of a reflex action?
I. CoughingII. Sneezing
III. Knee JerkBear in mind that these responses are rapid to avoid harm to the body
-
8/6/2019 Coordination and Control
4/47
4
COORDINATION IN MAN
This is the process by which receptors detect stimuli both internal and
external, then passing on information to effectors causing them to respond
appropriately. This maximizes the chance of survival.
Coordination is brought about by the nervous or endocrine system. Sense
organs provide us with information about our surroundings and as a result
we are able to perform a wide range of activities daily. Responses to stimuli
may be made by muscles or groups of secretory cells called glands; together
known as effectors.
Let us look at the following concepts
1. Stimuli2. Sense organs3. Glands
Stimuli (singular stimulus)
A stimulus is simply a change in the environment e.g. a change in light
intensity or a change in pressure on the skin.
Various sources of stimuli in the environment
1. Light energy2. Sound energy3. Temperature changes4. Pressure (touch)5. Chemical changed
Sense Organs
A sense organ may be defined as a part of our bodies made up of a number
of types of tissue and cells which detect stimuli. Examples of parts of our
bodies that respond to or detect stimulus are the eyes (respond to light in
particular the cells in the retina), the tongue (responds to chemical changes.
in particular in our taste buds), the ears detect sound and the nose has small
receptors which detect various smell/scent.
-
8/6/2019 Coordination and Control
5/47
-
8/6/2019 Coordination and Control
6/47
6
HOW VARIOUS PARTS OF THE BODY REACT TO CHANGES IN
THE ENVIRONMENT
1. How does the body respond to light energy?Study the diagram below
STRUCTURE OF THE EYE
Objective: Describe and identify from a drawing a horizontal section
through the eye and optic nerve
Fig. 1
1. Iris2. Conjunctiva3. Aqueous humour4. Cornea5. Pupil6. Lens7. Suspensory ligaments8. Cilary muscles9. Vitreous humour10.Choroid11.Selera/Selerotic coat
external eye muscle
choroid
optic nerve
sclera
retina
blind spot
vitreous huimourciliary muscle
iris
pupil
cornea
lens
suspensory
ligaments
aqueous
humour
fovea
conjunctiva
-
8/6/2019 Coordination and Control
7/47
7
12.Retina13.Fovea/Yellow spot14.Blind spot15.Optic nerve
FRONT VIEW OF THE EYE
Fig. 2
If possible observe the eye of a friend or simply observe your own eye in themirror and compare it to the diagram above.
FUNCTIONS OF THE EYE
We are able to see things when light is reflected from them
We will now examine how each part of the eye aids in the overall function
of seeing objects.
Eye lid
sclera
pupil
iris
tear
gland
tear
duct
-
8/6/2019 Coordination and Control
8/47
-
8/6/2019 Coordination and Control
9/47
9
The ConjunctivaThe conjunctiva is a delicate layer of tissue covering the entir surface od the
eye and inner surfaces of the eyelids.
Aqueous Humour
The fluid bathes the eye. It also helps to maintain the shape of the eye. Itsupplies the lens and the cornea with oxygen and nutrients,
LensThe lens is located just behind the iris. In collaboration with the cornea the
lens bend light rays that enter the eye.
The RetinaThe retina is made up of nerve tissue which sense light entering the eye.
Rods and cones are light sensitive cells found in the retina. Rods only detectblack and white images and cones detect colours. The images send impulses
through the optic nerve to the brain. The brain tranfers the impulses into
images that we can see.
ChoroidThe choroid is a black layer of tissue which contains a network of blood
capillaries which supplies the retina with nutrients and oxygen.
-
8/6/2019 Coordination and Control
10/47
10
.
Objectives: Describe the action of the components of the eyes in forminginverted images on the retina.
To achieve the above objectives we must examine how different parts of the
eye deal with light being reflected from images at various distances.
We are able to see things when light is reflected from them. Light rays
travels in a straight line in all directions. Light from objects in the
environment is reflected in all directions. The light rays reflected from an
object enters the eye. The curved surface of the cornea and lens both bend
light rays which enter the eye, so that each ray of light from the object forms
a point of light on the retina. Points of light will form a much smaller and
an upside down image of the object on the retina.
The cornea and the aqueous and vitreous humour are mainly responsible forthe bending (refractions) of light. The lens make final adjustments to the
focusing of the image unto the retina. For the image to be clear and in focus,
the light rays must meet exactly on the retina. We will look more closely
later at images focusing to a point before and beyond the retina and how
these may be corrected. Fig 4.3 and 4.4 illustrate how light from an object
produces a focused inverted image on the retina.
Fig. 4.3
-
8/6/2019 Coordination and Control
11/47
11
Fig 4.4 shows how the bending of light by the lens result in the formation of
an inverted image on the retina.
All the other components of the eye work to this end directly or indirectly to
focus the image (inverted) onto the retina. Table 4A outlines the functions of
the various components of the eye in forming an inverted image onto the
retina.
The pattern of sensory cells on the retina stimulated by the points or light
from the object will produce a pattern of nerve impulses which is sent to the
brain via the optic nerve. The brain interprets the pattern and so forms animpression of the real size, distance and upright nature of the objects. Of
course all this happens really, really quickly.
Table 4A summarizes the structure and function of the components of the eyeComponent Description Function
Selera Tough, white, fiberous coating. The frontis clear allowing light to enter the eye
(this is the cornea)
1. Protects the eye ball2. Keeps the spherical
shape of the eye
Conjunctiva Thin transparent membrane continuouswith the eyelids
1. stops the entry of gritinto the eye2. Protects the cornea
Cornea Transparent front part of the selera Refract or bend light rays unto
the retina
Aqueous humour Colourless fluid 1. Refracts light2. Helps maintain the shape
of the eye
Iris Coloured (eye colour brown, blue,Ggey etc) disc composed of muscles.
Controls the amount of lightentering the eye (passing through
Fig 4.4
-
8/6/2019 Coordination and Control
12/47
-
8/6/2019 Coordination and Control
13/47
13
How Lens Focus Light on to the Retina - Accommodation
Depending on the nearness of the object, the distance between light rays
changes as they travel from one point to another.
As said before, objects all reflect light andin orderfor us to perceive them we
have to bend and focus the light rays coming from each pointof the object. We
will now examine the mechanism involved in the focusing of light unto the
retina.
Not all rays need bending of equal amount unto the retina.
Focusing on near objects
Light rays coming from nearby objects are strongly diverging (separate,
going in different directions). Therefore they need to be bent equally strongly
inwards (converge) so that each point from that close/near object come to
focus on the retina. The lens ciliary muscle, and suspensory ligaments are
the components of the eye involved in accommodation.
Fig 4. 6 also shows accommodation for near objects. The mechanism involves
contracting of the ciliary muscle removing the tension on the suspensory ligaments.
The lens becomes fatter or more convex due to the elasticity and flexibility. A
thicker lens bends the light rays more strongly than a thin lens. The fatter shaped
lensis much better at bending light rays coming from a close/near object (light rays
aremoving away strongly from each other) than a thin lens which is better suited for
objectsat a distance (light rays almost parallel needs only a little bending)
-
8/6/2019 Coordination and Control
14/47
14
Focusing on distant objects
Light rays coming from an object in the distancetravel far enough so that the
rays of light coming from such an object will almost be parallelto each other.Theses rays would not require much bending.
The eye can produce a focused image of either a nearobject or a distant object.
To do this the lens changes its shape becoming thinner fordistant object and
fatter for near objects. The Change in shape is caused by contracting or
relaxing the cilliary muscle See fig. 4.5. The mechanism involves the ciliary
muscle relaxingand the suspensory ligaments holding the lens tight and thus
stretching the lens to a thin degree. The eye is now said to be focused for distantobjects. NBviewing far objects helps to rest the eye as the ciliary muscles are
relaxed. .
-
8/6/2019 Coordination and Control
15/47
Fig. 4.5
Distant Objects
Fig. 4.6
Near Ob ects
-
8/6/2019 Coordination and Control
16/47
16
Summary of behaviour of components during focusing
Viewing Lens Suspensory
ligaments
Ciliary
muscleDistant objects thin tightened relaxedNear objects thick looseded contracted
-
8/6/2019 Coordination and Control
17/47
17
The function of rods and cones in the retina in transforming
light energy into nerve impulses
As noted before light sensitive cells within the retina are of two kinds i.e.
rods and cones. Rods are extremely sensitive to light and can detect variousshades of grey/black and function in dim light or very low light intensities.
However, rods cannot distinguish colours and because of this they do not
detect edges well and produce poorly defined imaged (that is at low light
intensities). Rods are mostly located on the edge of the retina. Objects in dim
light are therefore seen more clearly from the corner of the eye.
The cones on the other hand are sensitive to colour and function in only
higher light intensities. This is why colours are not obvious at dark (when
the sun goes down at evening time. The cones are also sensitive to edges, so
they (produce sharp images which attest to the fact that we see more clearly
with brighter light.
The centre of the retina contains a tiny pit densely packed with
approximately 3 million cones called the fovea. The fovea is the most
sensitive part of the retina. The brightest rays are focused here. This part of
the eye produces the sharpest image which is why we tend to move our eyes
and our head so that the image of the object we want to see clearly falls in
that area.
The action of circular muscles in regulating entry of light into
the eye
Remember that a reflex action may be defined as a rapid automatic response
to a stimulus change in the environment by a muscle or a gland which does
not require conscious control or a process of thinking. It is a response system
geared towards protecting the body and the parts thereof.
With the consent of a friend shine a flashlight into his or her eyes and watch
closely to what happens to the iris and subsequently the pupils.
-
8/6/2019 Coordination and Control
18/47
18
What happens when bright light is shone into the eyes?
A reflex action occurs.This is because the cells of the retina are stimulated, generated nerve
impulses that are taken to the brain by a special nerve. (sensory nerve). A
message is then sent from the brain via another special nerve (intermediate
then to a motor) to a circular muscle of iris causing them to contract, thereby
reducing the pupil and hence limit the amount of light entering the eye. This
occurs within a fraction of a second.
There are two types of reflex: Cranial reflex which occurs in the head e.g.
blinking and swallowing. Cranial is controlled directly by the brain. The
other is the spinal reflex e.g. the knee jerk. These are controlled by thespinal chord.
All reflex action follows a similar path. Even the action is without thought
the information is picked up by the brain, which determines the details of
your final response. For example covering the eyes with the hands will offer
more protection depending on the intensity of the light. The stimulus picks
up by the receptor cells of the retina are sent directly to the brain and does
not involve the spinal chord. Whereas with other muscles of the body,
message is sent to the brain and the spinal chord.
Otherwise when there is not enough light the opposite happens, resulting in
the relaxing of the circular muscles of the iris, hence opening the pupils
allowing as much light to enter as is present.
Eye Diseases
1. Long/far sighted (hyperopia)Someone who has this condition can see objects in the distance
clearly, but objects nearby maybe blurry. This occurs because the
cornea and the lens are not evenly and smoothly curved and light rays
are not focused properly.
-
8/6/2019 Coordination and Control
19/47
19
2. Short/near sighted (Myopia)Someone with this condition can see near objects clearly but distant
objects do not properly focused. This occurs because the eyeballs are
toolong or the cornea is too curved so that the light entering the eye is
not properly focused.
3. AstigmatismSomeone with this condition experiences blurred vision due to either
an irregular shaped cornea or lens. This prevent light from focusing
properly on the retina and as a result distant objects are blurred.
4. Colour blindnessThe individual only sees black and white. This results from the failure
of the nerve supply of cones or failure of the cones themselves.
Hyperopia, myopia and astigmatism can be corrected by wearing
prescribed glasses, contact lens and laser surgery.
-
8/6/2019 Coordination and Control
20/47
20
Worksheet 1
Label the following parts on the eye above
a. Corneab. Pupilc. irisd. lense. suspensory ligamentsf. ciliary muscle
2. Name the part of the eye that decreases in size when a bright light is shone
into the eye.
-
8/6/2019 Coordination and Control
21/47
21
3. Explain what happens to the iris and the pupil (a) in dim light (b) bright
licht.
Dim Light
Bright light
4. Explain how the eye is nourished?
5. Explain how images are formed on the retina.
(4 marks)
6. You look at a car at a distance and then look at your book in your hand.
(1) Explain the changes the eye would go through to focus the book in
your hand away from the car in the distance.
_____________________________________________________________
_____________________________________________________________
(4 marks)
-
8/6/2019 Coordination and Control
22/47
22
(ii) State the name of the process explained in a(i) above.
7. Explain why objects in dim light are seen more clearly from the corner of
the eye?
8. A boy walks into a dimly lit room from a bright sunny day on the out side.
Explain how the eye would adjust to this environmental change.
9. (i) What is astigmatism?
(ii) How can it be corrected?
-
8/6/2019 Coordination and Control
23/47
23
THE NERVOUS SYSTEM AND ITS DIVISIONS
Objectives: State the main divisions of the nervous system
The nervous system consists of many nervous or nerve cells ofdifferent types. Almost like a big system made up many smaller
systems the nervous system is where all the sensory information
picked up by receptors (internal and external) are sent and reflex
actions and other actions are coordinated and worked out.
The main divisions of the nervous system are the: The Central Nervous System (CNS) The Peripheral Nervous System (PNS)
The CNS consists of the brain and the spinal cord which is enclosedby the cranium and vertebral column respectively
Fig. 4.7
Human Nervous System
Central Nervous
S stemPeripheral Nervous
System
Brain SpinalCord
Cranial/Sensory
Spinal/Motor
-
8/6/2019 Coordination and Control
24/47
24
The PNS consists ofpaired cranial/sensory nerve and spinal/motornerve There are 12 pairs of cranial nerves that control the function of
smell, vision, taste, facial expression, tongue movement etc.
These nerve comes from the base of the brain (cranial) and go tomainly structures of the head e.g. pair of eyes and pair of ears. Cranial
nerves go to both sides of the head in a pair. Spinal/ Motor nerves
come from out of the spinal cord, running to the pair of arms, legs and
various structures in the trunk (like the kidneys).The spinal/Motor
nerve control movement.
Fig 4.8
The brain and the spinal cord make up the central nervous system.
-
8/6/2019 Coordination and Control
25/47
25
Objective : Distinguish between neurone and nerve
If you are ever asked to distinguish between a neurone and a nerve (orif you want to know) just think of a rope.
Like a rope the nerve is made up of many single strands of fibres. Thestrands fibres that make up the rope are similar to that of the neurons
that make up the nerve. However, the single strands are intertwined.
In other words, a nerve of the CNS of which there are many, consistsof bundles of fibres (neurons) bound together or held together in a
sheath. This sheath is a tough material called connective tissue or
nerve sheath. .
Therefore neurons do not run through our bodies on their own, but areusually in several hundreds (found in one nerve). An example of a
neurone.
These help us to respond quickly to harmful stimuli which is usuallyour first defense against danger.
Fig. 4.9
neurone
-
8/6/2019 Coordination and Control
26/47
26
Nerve consists of several neurones
HOW DOES IT WORK?
The nervous systems main function is to carry or transmit messagesfrom one part of your body to another.
The function of our nervous system is facilitated or made possiblebecause of a network of nerve fibres (neurons) running throughout our
body.
The network of nerve fibres work pretty much like telephone cables.Messages are taken from one end to another along cables.
Why is such a network so essential to the human body? It is simply forcommunication; Just imagine if we did not have this network.
-
8/6/2019 Coordination and Control
27/47
27
Objective: State the role of the sensory, intermediate and relay
neurone and spinal synapses
Role of Neurone and Synapses
Before we go any further, I hope we are comfortable with what nervesare as opposed to neurons. A nerve leading away from a receptor
consists only of sensory neurone. A nerve leading to muscle consists
of motor neurons. Sensory intermediate/relay and motor neurone are
also referred to as nerve cells.
Characteristics of Nerve CellsAs you know by now a whole nerve cell is called a neurone/neuronThere are long processes or extensions from the cell bodies of the
nerve cells called dendrons. Dendrons conduct/carry impulses towardsthe cell body.
Axons conduct/carry impulses away from the cell bodyAxons and dendrons are surrounded by myelin sheathThe sheath is for:
1. Insulation of the electrical impulses
2. For fast and efficient movement of the impulses inside the
neurone
Additionally there is what we call nodes or little junction along thelength of the neuroneThese are small gaps in the sheath which increase the rate of
conduction of impulses along the neurone
The myelin sheath cause electric impulses to move rapidly by jumpingnode to node along the length of the fibre.
Role of Spinal SynapsesSynapses are small gaps between dendrites of adjacent neurone.
They allow a large number of neurone to interconnect and ensure
that impulse travel in one direction only.
A nerve impulse can only travel so far along a neurone. Eventuallyit reaches the end of the axon. Usually positioned very close to
another or to a muscle cell or gland.
When a nerve impulse gets to the end of an axon, It must cross thesynapse if it is to continue.
-
8/6/2019 Coordination and Control
28/47
28
Messages do not just jump across a synapses. Instead they arecarried by chemical messengers called neurotransmitters.
When the nerve impulse arrives at the synapse it cause the releaseof chemicals from vesicles (or little bubbles).
The chemicals are packaged in these vesicles at the top of the axonThe neurotransmitters diffuse across the synaptic space and bind to
receptors in the membrane on the other side to make an impulse
flow in the other neighbouring neurone
Synapses will occur at the point or junction of connection betweenrelay neurons and sensory neurons
Objective: Describe and recognize from a drawing a simple spinal reflex
arc. You must be able to describe, i.e. state in words or by use of
drawing what a simple reflex arc is?
A Simple Spinal Reflex Arc
When Paul touches the lit match the receptor cells/pain sensors in his
skin pick up the change in temperature (heat) in the environment and
send a stream of nerve impulse through the sensory neurone of the
dorsal root which runs up the arm to the spinal cord.
In the spinal cord, a synaptic connection is made with a relay or
(intermediate) neurone of the ventral root which is stimulated to
generate its own impulse.
This impulse then travels across another synapse to the motor neurone
in the same spinal nerve to an effector muscle which is stimulated to
contract so that the hand is withdrawn
The importance of this action is to protect Paul from being burnt.
Reflex action aids survival.
-
8/6/2019 Coordination and Control
29/47
29
Fig 4.10
A Reflex Arc
Study the diagram carefully. You may be asked to reproduce it or parts
of it. Note the connection of the three neurone (the sensory neurone, the
relay or intermediate and the motor neurone)
Role of Each type of Neurone1. Sensory neurone: These conduct impulses from receptors or sensory
cells to the CNS.
2. Motor neurons: These conduct impulses from the CNS to theeffector, which is either a muscle or a gland
3. Intermediate neurone: Conduct impulses throughout the CNS,linking sensory and motor neurone
Steps to the Pathway of Spinal Reflex Arc
1. Stimulus- change in environment outside or within the body e.g.change in temperature or pressure (outside) or decrease/increase in the
glucose concentration in the blood before or after a meal.2. Specific receptors are stimulated: initiation of impulse3. Impulse generated travels along sensory neurone and into the spinal
cord.
4. Message/impulse from a sensory neurone is linked to a motorneurone via a relay/intermediate neurone
Impulse leave spinal cord and travels along motor neurone
-
8/6/2019 Coordination and Control
30/47
30
5. Impulse cause effector (e.g. muscle) to contract causing a action/response to occur e.g. withdrawal of hand from heat source or leg to
rise/kick forward upon tapping below the knee jerk response)
There are two types of reflex: Cranial reflex which occurs in the head e.g.
blinking and swallowing. Cranial is controlled directly by the brain. Theother is the spinal reflex e.g. the knee jerk. These are controlled by the
spinal chord.
-
8/6/2019 Coordination and Control
31/47
31
H0RMONES
We have looked at how the body responds to external stimuli e.g. heat, light
cold etc. Let us now discuss how our body responds to internal stimuli.
Our bodies also coordinate to respond to internal stimuli (changes) which
function mainly in keeping the internal conditions at a normal level.
For example, a person who has difficulty in maintaining their blood sugar at
a standard level is said to be diabetic. The hormone insulin from the
pancreas controls blood sugar levels.
What is the function of insulin and glucagon?
Insulin helps your liver control the amount of glucose in the blood. Ifyou eat a meal, particularly one containing a lot of glucose, the levels
of glucose in your blood goes up (because digestion releases glucose
from complex sugars and starch).
Islets of Langerbans in the pancreas detects this change in the bloodsugar level (stimuli) and then secreats insulin into the blood.
When insulin arrives at the liver and muscle, it makes them absorbglucose from the blood, where it is used in the muscles for respiration.
Respiration also occurs in the liver but the main action of the liver isthat of converting the glucose or building up into glycogen molecules.
Why? Because it is useful and effective storage form of
carbohydrates. Glycogen is stored in the liver and muscles as
glycogen granules.
When the blood glucose has dropped to the right level, the pancreasstopped secreting insulin and the liver and muscles stop taking up
glucose from the blood.
This control of the blood glucose is an important part of homostasis(maintaining the constant conditions of the body despite the changesin the surroundings).
On the other hand after not eating for some time (fasting), the glucoselevel in the body falls below the normal. This change in blood glucose
level is detected by cells of the Islets of Langerbans.
The hormone glucagon is secreted into the blood. When glucagonarrives at the liver cells, it cause the breakdown of glycogen into
-
8/6/2019 Coordination and Control
32/47
32
glucose. What would this do? This action would release glucose
from the storage molecule into the blood until normal glucose levels
are restored.
If changes internally are not addressed or responded to, the bodywill not function at an optimal or efficient level. Hormones are
responsible for regulating body processes. If a person has problems
maintaining their salt or sodium level they are said to be hypertensive
(high blood pressure) or hypotensive, (low blood pressure). This
shows that an inability to maintain a constant internal environment
leads to disease conditions or harmful effects.
Nerves can carry electrical messages very quickly from one part ofyour body to another, but your body also uses chemical messages
though not as quick as impulses. These chemicals are calledhormones.
-
8/6/2019 Coordination and Control
33/47
33
What are hormones?
They are chemical substances produced by glands and
transported by the blood stream to control the activities of
certain cells or organs.
Hormones are chemical messengersThey carry messages from glands to organs.This is similar to neurons carrying an impulse
RevisionA gland is a group of similar cells which manufacture and secrete substances
such as hormones and enzymes. An organ is a part of the body whichfunctions as a unit, e.g. heart, kidneys, lungs. Tissues are grouped together to
form organs.
Glands are either ducted or ductless. Ducted glands are those which secrete
enzymes through ducts to the organs needed. Examples include the salivary
gland which secretes saliva into the mouth and the sweat glands into the
skin. Ductless glands are those which secrete hormones directly into the
blood stream. These include the adrenal and the pituitary gland.
Hormones are secreted directly into the blood stream via ductless glands
also called endocrine glands into the blood stream. They travel in the blood
stream to targeted tissues or organs. Cells respond to hormones when they
express specific receptors for that hormones i.e. cells have protein receptors
which recognize the hormone and accepts it. The message that is delivered
by the hormones can only be received by organs that will act on that
message (effectors)
Hormones are responsible for the processes of growth and development,
metabolism, sexual function, reproduction and mood. Some hormones causequick responses such as adrenalin but most are very slow.
-
8/6/2019 Coordination and Control
34/47
34
Hormones when released in blood becomes dissolved in the placenta.Although the blood may carry many hormones at a time, they only
affect certain parts of the body. So one could say that hormones are
specific, for a specific effector.
How are hormones dealt with after use?
Once they are used, hormones are changed in the liver to inactivecompounds and are excreted by the kidney. Hence, inactive hormone
compounds form apart of the urine after it has been used.
The human endocrine system consists of endocrine gland whichsecreted hormones directly into the blood fig 4.12 below show the
positions of the main endocrine glands of the human body. Table 4B
shows the different hormones that are secreted by each gland.
Fig, 4.12
The endocrine system consists of endocrine glands which secrete hormones
directly into the blood
-
8/6/2019 Coordination and Control
35/47
35
TABLE 4B
The table shows where hormones are made and secreted from and their
function in the body.
Gland Hormone Function/ effect on body
Pituitary Gland (master
gland)
Pituitary growth
hormone
Antidiuretic hormone
(ADH)
Stimulates growth, promoting
bone growth
Secreted when plasma becomes
too concentrated. Stimulates
kidneys to reabsorb more water
from filtrate
Thyroid glands Thyroxine Controls physical growth, mental
growth and metabolic rate. Cause
eretinism: if too little is producedthere is retarded physical and
mental development.
Too little: Low metabolic rate,
sluggishness, obesity: Too much :
high metabolic rate, weight loss,
overactivity, fast heart beat.
Adrenal Gland Adrenalin
When frightened, excited, anxiou
relesed in large amounts
Speed up metabolism, byincreasing blood sugar level,
heartbeat, breathing rate and
blood supply to muscles.
-
8/6/2019 Coordination and Control
36/47
36
Kinds of glands
The salivary glands which are found beneath the tongue. They secretesaliva into the salivary duct, which carries it to the buccal cavity(mouth) or empties into the mouth.
The pancreas is actually two glands in one. Most of the pancreas is anordinary gland (ducted) which make pancreatic juice. Which flows
along the pancreatic duct and into the duodenum (revise notes on
digestion)
The rest of the pancreas consists of a group of cells called the (Isletsof Langerbams)
The Islets of Langerbans do not make pancreatic juice (carries outdigestive functions), but make the hormones; Insulin and Glucagon
Insulin and glucagon are secreted directly into the blood, so the isletsof langerbans are endocrime glands
-
8/6/2019 Coordination and Control
37/47
37
Objective: describe the role oestrogen and progesterone in the
menstrual cycle and in pregnancy.
MALE HORMONES
Male sex hormones are called androgens. The most important of theseis called testosterone. This is made in the testees or scrotal sacs.
The hormones regulate the development of the male sex organs. Theyalso control the development of secondary characteristics. These
characteristics include:
Growth of facial and pubic hair Breaking of voice (more mature sound) Muscular development
FEMALE HORMONES
In the female, the ovaries produce two groups of hormones; oestrogenand progesterone Oestrogen regulates the development of the
female sex organ, the female secondary characteristics, and the
menstrual cycle. The secondary characteristics include.
Growth of pubic hair
Development of breast Pelvic girdle widening so as girls develop they are able to
carry a child
Males, once into puberty, make sperms all the time. At birth, a femaleOvary contains many thousands of potential egg cells and ova.
However, it is not until she is into puberty that she is able to produce
an egg. After puberty only one egg is developed each month and this
varies for different people. Somewhere around late 40s and early
50s, she no longer produces eggs. All her life as an egg producing
entity, a womans body is controlled by her sex hormones. When thereis a cease in production or reduction of the hormones, the female ages
rapidly and experiences many discomforts, which is why women that
are in menopause (no longer experiencing menstruation) are often
advised or should consider hormone treatment and therapy.
-
8/6/2019 Coordination and Control
38/47
38
Role of Oestrogen and Progesterone in the Menstrual Cycle
Since women only produce eggs at times the sex hormonesare released into the blood. The sex Hormones play a special
role in the process and must somehow be regulated.
The release of an egg from the ovary is called ovulation. Thisprocess occurs on a monthly basis.
Ovulation is a part of what is called the menstrual cycle ormenstruation.
Menstrual cycle is the actual breaking down of the uteruswalls in the event that the ovum released did not get fertilized
by a male sperm cell. Fig. 4.14 summarizes the role of
oestrogen and progesterone, observe carefully different
stages.
-
8/6/2019 Coordination and Control
39/47
39
Summary of Ovulation
1. Potential ova (plural) inside primary follicle2. Ovum matures inside graafian follicle and produces oestrogen that
builds up the walls of the uterus.
3. Ovulation - graafian follicle moves to edge of ovary, burst releasingmature ovum and the follicle remaining stops secreting oestrogen
4. The follicle becomes a corpus luteum, which starts producingprogesterone, which keeps the uterus lining thick and spongy.
OvulationThe graafin follicle stops secreting oestrogen and becomes a
corpus luteum: the corpus luteum starts to secrete another
hormone progesterone.
Progesterone keeps the uterus lining thick, spongy and wellsupplied with blood in case the egg is fertilized.
If fertilization does not occur, then the corpus leteum graduallydisappears.
Progesterone is not secreted anymore and so the lining of theuterus breaks down and menstruation happens.
The cycle continues when a new follicle starts to develop in theovary a few days after menstruation
-
8/6/2019 Coordination and Control
40/47
-
8/6/2019 Coordination and Control
41/47
41
Fast-acting Hormones
Fast and effective, yet very short-lived (think of a fire-craker)This group comprises of hormones, which includes insulin and
adrenalin (the flight or fight hormone) The effect is very fast actingand effective but very short-lived.
-
8/6/2019 Coordination and Control
42/47
42
Objective: Distinguish between the hormonal and nervous control
systems
The nervous system and the endocrine systems are the two communicationsystems that regulate all responses and functions of the body.
Table 4c illustrates the distinguishing features of the Endocrine and
nervous Communication system
Nervous System Endocrine System
Control Control
Chemical Substance or Impulse
Messages carried as electrical impulses Messages carried by chemicalalong nerves (bunch of neurone messages in the blood
enclosed by a protein sheath
Speed of Response
Messages are sent rapidly Messages are transmitted slowly
Widespread or Localized Responses
Messages are carried to the precise Messages are carried to moreRegion of the body generalized regions or an area of
the body
Long-term or Short-lived Response
Messages are short-lived or Messages have a long-term or l
Short-lasting effect on the body have a long-lasting effect on the
body
Study the table focusing your attention on how systems differ. Note -
1. Whether or not chemical substances or impulse are used to respond2. What is the speed of the response3. whether or not there is a widespread or localized response4. Long-lived or short-lived response
-
8/6/2019 Coordination and Control
43/47
43
Worksheet 2
1. Define a reflex action (2 marks)___________________________________________________________
___________________________________________________________
2. Give an example of a reflex action (1 mark)___________________________________________________________
___________________________________________________________
3. Paul accidentally touches a hot plate and quickly withdraws her hand.Describe the series of events in the nervous system that would cause
paul to react this way. (6 marks)
______________________________________________________________________________________________________________________
___________________________________________________________
___________________________________________________________
___________________________________________________________
___________________________________________________________
___________________________________________________________
4. Explain the importance of Pauls reaction (1 mark)___________________________________________________________
___________________________________________________________
5. Sketch a diagram of the human body showing three glands (6 marks)
-
8/6/2019 Coordination and Control
44/47
44
6. State the hormone associated with each gland shown. (3 marks)
_____________________________________________________________
_____________________________________________________________
_____________________________________________________________
7.
Refer to the diagram in this unit showing the pathway by which messages
travel in bringing about the knee jerk. When the tendon is tapped, receptorsin the muscles are stretched and this causes the messages to be set off.
(i) Which structure is stimulated by the tapping of the hammer?_____________________________________________________ (1 mark)
(ii) Give the name of the structure which carries impulses awayfrom the spinal cord?
_____________________________________________________ (1 mark)
(iii) Which structure shortens or moves as a result of the reflex?_____________________________________________________ (2 marks)
*Remember when muscles contract they shorten allowing movement to
occur.
(iv) Name the structure which carries the message back to the muscle for
the appropriate action?
_____________________________________________________(3 mark)
8. (i) Your lunch was a meal rich in carbohydrates and a very sweet soda.
What happens will happen to your blood sugar level?
_____________________________________________________________
_____________________________________________________________
-
8/6/2019 Coordination and Control
45/47
45
(2 marks)
(ii) What action is taken by the body to return this to a normal level?
_____________________________________________________________
______________________________________________________ (4 mks)
(iii) Why is it important to control the internal environment of the body?
______________________________________________________ (1mls)
16. Define the term drug dependence
______________________________________________________ (2mks)
9. List below the four (4) main differences between control by the nervous
system and control by the endocrine system.
Nervous Endocrine
1.
2.
3
4
18. State what you would tell someone about the effects of heroine, who is
attempting to start this use.
Short-term
_____________________________________________________________
___________________________________________________ (2 marks)
Long-term
_____________________________________________________________
____________________________________________________ (2 marks)
-
8/6/2019 Coordination and Control
46/47
46
10. Distinguish between a neurone and a nerve.
_____________________________________________________________
_______________________________________________________(2 mks)
20. Distinguish between quick-acting hormones and fast acting hormones. In
both cases give an example.
_____________________________________________________________
_____________________________________________________________
_____________________________________________________________
_____________________________________________________________
______________________________________________________(2 mks)
Essay Questions (50 marks)
1. A man pricks his finger while cutting some rose buds. He immediatelywithdraws his hand from the source of pain and cries out. Explain
what is happening to his nervous system to bring about these two
responses.
2. Describe clearly the role of oestrogen and progesterone in themenstrual cycle and in pregnancy. Use annotated diagrams to assist
your explanation.
3. Discuss the misuse of alcohol in Jamaica? What suggestions can youoffer in reducing their ill effects?
Include in your answer a consideration of the consequences for:
(i) The bodys ability to respond to stimuli-reaction time(ii) Coordination(iii) The ability to make quick rational decisions
-
8/6/2019 Coordination and Control
47/47