10. Coordination and Response

10.1 Nervous control in humans

Human Central Nervous System

Human Central Nervous System

• A: ……………………………………………………………..

• B ………………………………………………………………

• C:………………………………………………………………

Human Central Nervous System

Motor neurons (effectors) Sensory neurons (+ receptor)

Human Central Nervous SystemRelay (intermediate) neurons (connectors) Reflex arc

Human Central Nervous System

• Sensory neuron: ……………………………………………………………………..

• Relay neuron: ……………………………………………………………………..

• Motor neuron: ……………………………………………………………………..

Reflex Arc

Reflex Action

• Receptor: triggered (stimulus)• Sensory neuron: excited• (relay neuron: excited)• Motor neuron: excited• Effector: triggered (response)

Reflex Action

• Receptor: …………………………………………………….• Sensory neuron: ………………………………………….• (relay neuron: ……………………………………………..• Motor neuron: …………………………………………….• Effector: ………………………………………………………

Reflexes

Reflexes

• Pain• SN• Spinal cord • RN• MN• Effector muscle• Contraction• Movement

• Sound• SN• Brain• MN• Effector gland• Release of product

Muscle Action

Muscle Action

• Biceps and Triceps are antagonistic muscles. Muscles can only contract. To relax (stretch) a muscle, another force is needed. Usually this is achieved by an antagonistic muscle. Sometimes the shape of the muscle (eg ring muscles) or gravity acts as an antagonist.

• Antagonistic muscles are essential for controlled movement.

Sense Organs

• Receptor (cells) change stimulus into an electrical impulse to be carried by a sensory neuron to the CNS (areas of the brain). Here the impulse is translated into a sensation.

Sense Organs

Sense OrgansSense organ Stimulus Receptor cells Brain centre Result

Eye

Ear

Nose

Skin

Tongue

Eye

Ear

Nose

Skin

Tongue

Structure of the Eye

Structure of the Eye

• Conjuctiva• Cornea• Iris• Pupil• Lens• Ciliary muscle• Suspensory ligament

Structure of the Eye

• Conjuctiva ………………………………………………….• Cornea ……………………………………………………….• Iris ……………………………………………………………..• Pupil ………………………………………………………….• Lens …………………………………………………………..• Ciliary muscle …………………………………………….• Suspensory ligament ………………………………….

Structure of the Eye

• Sclera• Choroid• Retina• Fovea• Optic nerve

Structure of the Eye

• Sclera …………………………………………………………...• Choroid ………………………………………………………..• Retina …………………………………………………………..• Fovea ……………………………………………………………• Optic nerve …………………………………………………..

Function of the Eye

Accomodation

Accomodation

• Object far away: lens as flat as possible (not accomodated)

• Object between 6 m and 30 cm: lens gets thicker (rounder), accomodation

• Object close by: lens as thick as possible (fully accomodated)

Accomodation

• Object far away: …………………………………………………………………….• Object between 6 m and 30 cm: …………………………………………………………………….• Object close by: …………………………………………………………………….

Pupil reflex

Structure of the Retina

Structure of the Retina

• Rods: ………………………………………………………………………………………………………………………………………………

• Cones: ………………………………………………………………………………………………………………………………………………