Ch 7. Control and Coordination

Stimuli

Changes in the environment to which organisms respond and react.

Response

The visible reaction or movement according to a stimulus.

Coordination

The working together of various organs to produce a proper response to a given stimulus.

nervous coordination

Control of organ functions through the nervous system.

chemical coordination

Control of organ functions through secretion of hormones by the endocrine system.

Neuron

structural and functional unit of the nervous system.

Cyton (Cell Body)

Receives information and conducts it through the axon.

Dendrites

Finger-like projections that conduct nerve impulses towards the cell body.

Axon

The longest extension from the neuron cell body carrying impulses away from it.

Synapse

The functional junction between the axon of one neuron and the dendrites of the next neuron.

Impulse

The message that travels across nerves in the form of chemical and electrical signals.

Sensory Nerve

Nerve that transmits messages from the sense organs to the brain.

Motor Nerve

Nerve that carries messages from the brain to muscles and glands.

Reflex Action

Quick, spontaneous, and involuntary response against a stimulus.

Reflex Arc

Pathway of reflex action from receptors to effectors.

(CNS)

Comprises the brain and spinal cord.

fore brain

cerebrum - intelligence, sight hearing

sensory- recieve impulses from receptors

control voluntary muscle movements

hypothalamus- regulates body temperature, hunger, and thirst.

midbrain

controls movement of head, neck and trunk

reflex movements of eye muscles

hindbrain

cerebellum

• coordination of voluntary movements, balance, and posture;

• medulla oblongata - heart rate and breathing, salivation and vomiting

• pons- controls sleep and respiration.

Pituitary Gland

Secretes growth hormone which regulates body growth.

controls activity of other glands

thyroid Gland

Secretes thyroxine which regulates metabolism.

iodine and is essential for thyroxine production.

goitre A condition resulting from iodine deficiency, leading to an enlarged thyroid gland.

Insulin

Hormone that lowers blood glucose levels,

pancreas

diabetes produced by the beta cells of the pancreas

less amount of insulinin response to high blood sugar levels.

Adrenaline

Stress hormone that regulates heart rate and blood pressure.

Photoreceptors

Sensory receptors in eyes that respond to light stimulus.

Thigmotropism

Growth response of plants to touch.

Auxin

Plant hormone promoting cell elongation and growth at stem and root tips.

Ethylene

Plant hormone responsible for ripening of fruits.

Abscisic Acid

Growth inhibiting hormone causing wilting of leaves.

neurotransmitters

Chemical substances released at the synapse to transmit signals between neurons.