Control and Coordination – Detailed Exam Notes

Receptors

Specialised dendritic tips located mainly in sense organs that detect stimuli.

Reflex Actions

Rapid, automatic responses executed without conscious thought.

Reflex Arc

The pathway of a nerve impulse in a reflex action, typically involving a receptor, sensory neuron, interneuron, motor neuron, and effector muscle/gland.

Synapse

The gap between the axon terminal of one neuron and the dendrite/cell body of the next neuron or muscle cell, across which neurotransmitters are released.

Central Nervous System (CNS)

The brain and spinal cord, forming the main control center of the nervous system.

Fore-brain

The anterior part of the brain (cerebrum) responsible for thinking, memory, interpretation, voluntary actions, and the hunger centre.

Cerebellum

A brain region located in the hind-brain, responsible for precision, posture, and balance.

Medulla oblongata

A brain region in the hind-brain that controls autonomic functions such as heartbeat, blood pressure, vomiting, salivation, and breathing rhythm.

Nastic Movements

Plant movements independent of growth, such as the rapid folding and drooping of Mimosa pudica leaves upon touch.

Tropism

Plant growth movements that are directional responses to stimuli.

Auxins

A plant hormone synthesized at the shoot tip that promotes cell elongation, leading to bending toward light (phototropism) and mediating tendril coiling.

Hormones

Chemical messengers secreted by ductless glands directly into the blood, coordinating widespread and longer-lasting effects in animals.

Endocrine System

The system of ductless glands (endocrine glands) that secrete hormones directly into the bloodstream.

Adrenaline

A hormone secreted by the adrenal medulla during stress or fear, preparing the body for rapid action (fight-or-flight response).

Feedback Regulation

A regulatory mechanism where the output of a process (e.g., hormone level) inhibits or stimulates the process itself, maintaining homeostasis.