HUMAN NERVOUS SYSTEM & SENSE

ORGANS p118 - 157

Sub topic 1: Human nervous system

P120 - 121

Nervous system

Endocrine system

Stimuli

•Hormones as well as nerves enable all animals to respond to internal and external changes & stimuli.

•They also help the animal to co-ordinate various activities of the body.

•Internal stimuli = hunger, fright, reproductive urges etc.

•External stimuli = heat, cold, danger etc.

Sub topic 2: Central nervous system

P122 - 125

Meninges CerebrumCerebellum Corpus

callosumMedulla oblongata

Spinal cord

Sub topic 3: Peripheral nervous

systemP125 - 126

Peripheral Nervous System

Sub topic 4: Autonomic nervous

systemP126 - 127

Autonomic Nervous System

Sub topic 5: Structure and

Functioning of a NerveP127 - 129

Myelin Sheath AxonDendrite

Sub topic 6: A simple reflex arc

P130

Reflex action Reflex arcReceptor Effector

Reflex action: punching, blinking, sneezing, coughing, ducking,

squealing, vomiting etc.

Reflex arc: PNS CNS PNS Sensory Inter Motor

Receptors:Organ Eye Nose Tongue Tongue Ear

Skin

Sense Sight Smell Taste Taste Hear Touch

Effectors:

Muscle - Contracts, Relaxes = functions antagonistically

Gland - Endocrine or Exocrine = Hormones / Bodily fluids.

Nerve impulses are electrical messages that travel along the nerves at about 100m/s (roughly 360km/h).

The myelin sheath that consists of fat helps to insulate the electrical impulse to avoid the leaking of information.

Nodes of Ranvier act as booster sites to speed up the transmission.

Nerves / Neurons do not touch each other , there is always a space between the terminal branches of one and the dendrite of another.

The gap between neurons is called a SYNAPSE. p131

Because the gap exists, the electrical message is transformed into a chemical message and back to electrical.

The chemical transmission across the synapse is achieved via a NEUROTRANSMITTER.

Types of neurotransmitters: Acetylcholine Dopamine Epinephrine Serotonin

Sub topic 7: Disorders of the CNS

P134 - 135

Sub topic 8: Injuries to the CNS P136 -

137

Sub topic 9: Effects of drugs on the

CNS P138 - 139

Sub topic 10: Receptors p140

Interoceptors ExteroceptorsProprioceptors

Sub topic 11: Human Eye p141 - 148

Binocular vision AccommodationPupil reflex Short-

sightednessLong-sightedness AstigmatismCataracts

Accommodation of the eyeObjects closer than

6mObjects further than 6m

1. Ciliary body (muscle) contracts

1. Ciliary body (muscle) relaxes

2. Ring shaped muscle contracts

2. Ring shaped muscle relaxes

3. Suspensory ligaments relax

3. Suspensory ligaments contract

4. Pulling force on lens decreases

4. Puling force on lens increases

5. Lens more convex / rounder

5. Lens less convex / rounder (more concave)

6. Light rays are broken more

6. Light rays are broken less

Pupil Reflex / Pupillary Mechanism

Short-sightedness

Long – sightedness / Far sighted (Hyperopia)

Astigmatism

Cataracts

Sub topic 12: Human Ear p149 - 151