2. Coordination in Mammal
coordination is the way in which receptors detect stimuli, and then nerve impulses are sent to the effectors
in mammals, coordination is carried out through the activities of nervous system and the endocrine system

3. nervous coordination is brought about by transmission of nerve impulses between receptors and effectors through nerve fibres
endocrine coordination is brought about by hormones secreted from endocrine glands

4. What is Nervous Coordination ?
nervous system of mammal consists of central nervous system(CNS) and peripheral nervous system
CNS includes brain and spinal cord and the peripheral nervous system includes cranial nerves and spinal nerves

5. Structure of Neurones neurones make up nervous system in mammal
each neurone has a cell body and nerve fibres
cell body is a mass of cytoplasm with nucleus inside and it is called ganglion
nerve fibres are cytoplasmic processes of neurones and there are two types, one is dendron and the other is axon

6. dendron transmits nerve impulses towards cell body while axon transmits nerve impulses away from cell body
nerve fibres may be protected by a fatty layer which serves as an insulator to prevent the spread of nerve impulses and help to speed up the rate of transmission

7. direction of nerve impulses
cytoplasm
dendron
cell membrane
nucleus
nucleus of cell which makes the myelin sheath
axon
direction of nerve impulses

8. Types of Neurones
there are three types of neurones: sensory neurone, motor neurone and association neurone
- sensory neurone: transmits nerve impulses from receptor to the central nervous system
sensory neurone

9. - motor neurone: transmits nerve impulses from central nervous system to effectors. The axon branches at its end to form many motor end plates which are attached to muscle fibres
motor neurone
- association neurone: connects the sensory neurone to the motor neurone and also the neurones in the central nervous system

10. Nerve bundles of nerve fibres
neurone
bundles of nerve fibres
usually myelinated and surrounded by a sheath of white connective tissue
nerve fibre
nerve

11. impulses do not jump from one fibre to another because of the presence of fatty substance in nerve
in sensory nerves, there may be ganglia where the cell bodies are situated
nerve fibres found inside the central nervous system do not have insulating fatty layers

12. neurone

13. Nerve Impulses Transmitted in Nerve Fibre
stimulation of the receptors may initiate nerve impulses and this follows “All-Or-None” principle

14. ALL impulses are alike regardless of the site from which they are fired off
impulses travel very quickly in one direction from dendron to axon of the same neurone

15. Nerve Impulses Transmitted across the Synapse
neurones are not in direct contact with each other. A small gap called synapse exist between two neurones
impulses need to jump across the synapse as to travel from one end of axon to dendron of another neurone

16. Synapses

17. the chemical is unstable and will be destroyed later
synapse
ending of axon secretes a chemical which diffuses into synapse and stimulates the next neurone to pass on the impulse
the chemical is unstable and will be destroyed later

18. presence of synapse enables nerve impulses to travel only from axon of one neurone to dendron of another neurone
it also allows higher level of nervous coordination as one neurone can be linked with a number of other neurones

19. Central Nervous System
includes brain and spinal cord in higher animal
brain
spinal cord

20. Protection of Central Nervous System
skull
brain is enclosed in cranium of skull while spinal cord is enclosed in vertebral column
CNS is also enveloped in three layers of meninges and between the inner two layers is a cavity filled with cerebrospinal fluid
vertebral column

21. Functions of Cerebrospinal Fluid
act as a cushion for absorbing external shock
nourish neurones inside as it enables diffusion of oxygen and food to the nerve cells
it also filled up cavity called ventricle in brain and in the central canal of spinal cord
it also helps in preventing collapse of CNS

22. External view of the brain

23. Parts of Brain
brain is divided into three main parts: cerebrum, cerebellum and medulla oblongata
cerebrum
cerebellum
medulla oblongata

24. Brain--Cerebrum
lies in the front part of brain and divided into two cerebral hemispheres connected by nerve fibres
surface of cerebrum is highly folded to increase area for coordination
centre of thinking, memory, reasoning, imagination, learning and voluntary actions

25. divided into three functional areas
- sensory areas: receive impulses from receptors
- motor areas: send out impulses to effectors
- association area: correlates impulses from different receptors and assists in producing appropriate responses
association area
motor area
sensory area

26. Brain--Cerebellum lies below the back part of cerebrum
centre for muscular coordination and involved in control of body balance
damage of cerebellum will lead to a loss of ability to maintain balance

28. Brain--Medulla Oblongata
lies at the floor of cerebellum
reflex centre for controlling involuntary actions such as breathing, heartbeat, swallowing, coughing, sneezing and salivation
damage of medulla oblongata may lead to death

29. Medulla oblongata
medulla oblongata

30. Internal Structure of Cerebrum and Cerebellum
outer layer is made up of gray matter which consists of nerve cell bodies
inner layers consist of nerve fibres and is white in colour and is called white matter

32. Internal Structure of Medulla Oblongata
outer layer is made up of white matter while inner layer is made up of grey matter

33. Internal Structure of Spinal Cord
arises from medulla oblongata and runs through backbone of mammal
internal distribution of nerve cell bodies is similar to medulla oblongata which the outer cortex contains white matter while the inner cortex is in H-shaped and contains grey matter

34. in the central region of grey matter is central canal and filled with cerebrospinal fluid
reflex centre for controlling involuntary actions and it also transmits impulses to and from brain
white matter
grey matter
spinal nerve
central canal
spinal cord

35. Grey & White Matters spinal cord & cerebrum & cerebellum
medulla oblongata
cerebrum & cerebellum
grey matter
(cell body)
outer region
inner region
white matter
(nerve fibre)
outer region
inner region

36. Peripheral Nervous System
consist of cranial nerves and spinal nerves
these nerves leave CNS and run out to every part of the body
cranial nerve
spinal nerve

37. Cranial Nerves and Spinal Nerves
- twelve pairs of cranial nerves in mammal
- most of cranial nerves arise from lateral sides of medulla oblongata
Spinal Nerve
- there are 31 pairs of spinal nerves in human

40. Spinal Nerve dorsal root ganglion sensory neurone receptor (pain)
dorsal root (sensory nerve)
association
neurone
effector (muscle)
motor neurone
spinal cord
ventral root (motor nerve)

41. - all are mixed nerve carrying both sensory and motor neurones
- each spinal nerve has a dorsal root and ventral root
- dorsal root contains ganglion which contains nerve cell bodies

42. - cells in dorsal root ganglion are sensory neurones and impulses travel through dorsal root to spinal cord from spinal nerve
- ventral root carries motor nerve fibres and their cell bodies are found in H-shaped grey matter of spinal cord

43. Experiment to Initiate Knee Jerk Reflex
Investigation 15.3
Experiment to Initiate Knee Jerk Reflex

44. What happens to the leg immediately after tapping?
Ans: It kicks up at once.

45. Does the same action occur again if the knee is tapped the second time?
Ans: Yes.

46. Reflex Action
simple reflex action is a quick, inborn and automatic response of an animal to a stimulus and cerebrum does not involve in the response
protective in function and need not be learnt
same stimulus initiates the same responses at different times
examples like withdrawal from hot objects, blinking, coughing, sneezing and pupil size

47. Reflex Arc Knee Jerk Reflex
neural pathway between receptor and effector involved in a reflex action
example is knee jerk reflex
Knee Jerk Reflex
At the Receptor
receptor receives stimulus. In this case, tapping stimulates tendon of knee cap

48. At the Sensory Neurone
from ending of dendrons of sensory neurones, nerve impulses fired off
Across the Synapse to the Motor Neurone
through dorsal root of spinal nerve, impulses are carried to spinal cord

49. impulses jump across synapses to motor neurones in grey matter but in other reflex action, association neurones may involve
To the effector
impulses are further transmitted through ventral root to effector to produce responses

50. in knee jerk, effector is muscles in upper leg which it will contract when impulses are received so the leg jerks up and it is an example of spinal reflex action as only spinal cord is involved

51. Reflex arc : sensory, association, motor neurones
dorsal root ganglion
sensory neurone
receptor
(pain)
dorsal root (sensory nerve)
association
neurone
effector (muscle)
motor neurone
spinal cord
ventral root (motor nerve)

52. spinal reflexes can occur in deep sleep and do not depend on awareness but impulses can still pass form sensory neurones up the spinal cord to brain
other reflex actions like blinking, coughing and sneezing are cranial reflex action and take place in medulla oblongata

53. Voluntary Actions conscious response to a certain stimulus
involves cerebrum of brain and mammals are aware of all the steps of the response
may differ from time to time as mammals can gain experiences and store them in cerebrum so they can choose how to response to the same stimulus

54. Neural Pathway of Voluntary Action
receptor receives stimulus
sensory neurone carries nerve impulses to CNS
association neurone carries impulses to cerebrum
motor neurone carries impulses to effector
effector gives responses

55. Comparison between Reflex & Voluntary Actions
reflex action
voluntary action
pathway taken by nerve impulses
not involving cerebrum
involving cerebrum
control
automatic, not under control of the will
voluntary, under control of the will

56. response to the same stimulus always the same
reflex action
voluntary action
speed of response
quicker
slower
response to the same stimulus
always the same
different, depend on learning from previous experiences

57. To measure your Reaction Time
Investigation 15.4
To measure your Reaction Time

58. Does your reaction time improve with practice ?
mark on your thumb
Does your reaction time improve with practice ?
Ans: Yes.

59. Ans: The reaction time was quicker without ruler touching the hand.
mark on your thumb
Was your reaction time quicker with or without the ruler touching your hand?
Ans: The reaction time was quicker without ruler touching the hand.

60. mark on your thumb
Explain.
Ans: It is because the sensory pathway from eye to brain is much shorter than that from finger-tips to the brain.

61. Endocrine Glands ductless glands in body
secrete chemical messengers called hormones which diffuse directly into the blood
hormones are carried to target organs by bloodstream

62. Specificity and Effect of Endocrine Glands
usually, target organ respond to a particular hormones only so hormones are specific
hormonal coordination is slow and takes a longer time for response to appear but its effect can last for a long period of time

63. Comparison between Nervous & Hormonal Coordination
nervous coordination
nature of message transmitted
nerve impulse
hormone
method of transmission
nerve impulses transmitted along nerve fibres
hormones carried by blood vessels

64. widespread throughout the whole body localised to muscles and glands
hormonal coordination
nervous coordination
rate of producing response
fast
slow
duration of effects
short-term
long-term
widespread throughout the whole body
area affected
localised to muscles and glands

65. Locations of Endocrine Glands
pituitary gland: locate below cerebrum and it controls many other endocrine glands activities in body
thyroid glands: in neck
islets of Langerhans: in pancreas
adrenal glands: above kidney
ovaries: in female’s abdominal cavity
testes: in male’s scrotal sacs
pituitary

66. Sites of Six Main Endocrine Glands in Human Body

67. Negative Feedback Mechanism
secretion of hormones follows negative feedback mechanism which means that any decrease in the level of a factor switches on a series of corrective actions to restore the factor to normal level and vice versa
an example is insulin which is secreted by islets of Langerhans in pancreas to liver through blood vessels to control blood glucose level

68. in pancreas more insulin secreted high blood glucose level
after a heavy meal
liver glucose glycogen more glucose taken up by cells for respiration
normal blood glucose level

69. normal blood glucose level
liver glycogen glucose less glucose taken up by cells for respiration
normal blood glucose level
long time after a meal
low blood glucose level
in pancreas less insulin secreted

70. Effect of Sex Hormones
puberty occurs between the ages of years when a child become sexually mature
ovaries in females and testes in males become functional and secrete sex hormones for development of secondary sexual characteristics which are physical changes for sexual awareness

71. Secondary Sexual Characteristics
Boys
Girls
growth of pubic hair and hair on face (facial hair) and in armpits (axillary hair)
growth of pubic hair
breaking of voice and enlargement of larynx
growth and development of breasts

72. widening of hips(pelvic girdle) muscle development
Boys
Girls
widening of hips(pelvic girdle)
muscle development
widening of shoulders
more fat deposits under skin

74. ~ END ~