Neural Control and Coordination

To maintain the body's homeostasis, the functions of the organs and organ systems must be coordinated. Coordination is the process through which multiple organs interact and complement each other's functions. For instance, during physical exercise, the demand for energy increases to sustain heightened muscular activity, necessitating an increased supply of oxygen. This increased oxygen supply requires a higher respiration rate, faster heartbeat, and enhanced blood flow through the blood vessels.

1.0What is Neural Control and Coordination

• In the human body, the neural and endocrine systems jointly coordinate and integrate all the body's activities so that the organs function synchronized. 
• The nervous and endocrine systems are called the integrative systems of the body. 
• The neural system provides an organized network of point-to-point connections for rapid coordination, while the endocrine system integrates bodily functions through hormones. In all animals, the neural system consists of highly specialized cells called neurons, which detect, receive, and transmit various stimuli. In lower invertebrates, the neural organization is very simple. 
• For instance, Hydra has a basic network of neurons. Insects have a more advanced neural system, featuring a brain, several ganglia, and neural tissues. Vertebrates possess the most developed neural system.

2.0Control and Coordination of the Brain 

The human neural system is categorized into two main parts:

1. Central Nervous System (CNS): Comprising the brain and spinal cord, the CNS is the main hub for processing information and coordinating control.
2. Peripheral Nervous System (PNS): The PNS encompasses all the nerves that extend from the CNS, including those linked to the brain and spinal cord.

The PNS is divided into two divisions:- 

• Somatic neural system (SNS) relays impulses from the CNS to skeletal muscles and voluntary organs. 
• Autonomic neural system (ANS): It transmits impulses from the CNS to the body's involuntary organs and smooth muscles. The autonomic nervous system is further categorized into the sympathetic and parasympathetic nervous systems, which regulate involuntary functions, including muscle activity.

Nervous Tissue

Nervous tissue originates from the ectoderm and is specialized for receiving stimuli (Excitability) and transmitting messages (conductivity).

Neuron (Nerve Cell)

• It is the functional and structural unit of the nervous system.  
• It generates and transmits nerve impulses. 
• It is the longest cell in the body.  
• A neuron is a microscopic structure made up of three main parts:

(i) Cell body or Cyton 

(ii) Dendrites or dendrons 

(iii) Axon 

Generation and Conduction of Nerve Impulse (Conduction of Nerve Impulse along the Axon)

• Neurons are excitable cells due to their polarized membranes. 
• They exist in a salt solution with a higher concentration of Na+ ions outside and a higher concentration of K+ ions inside. The neural membrane contains various ion channels selectively permeable to different ions.

Synapse

• A nerve impulse is transmitted between neurons at junctions known as synapses. 
• A synapse comprises the membranes of a presynaptic neuron and a postsynaptic neuron, which a synaptic cleft may separate. 
• There are two primary types of synapses: electrical synapses and chemical synapses.

Neurotransmitters

Central Neural System

It includes the brain and the spinal cord. Approximately 70-80% of brain development occurs by age 2, with complete development achieved by age 6. The spinal cord fully develops between 4 to 5 years of age. The brain is the central information-processing organ of our body, acting as the 'command and control system.'

Brain Meninges

• Three layers of connective tissue called the meninges, safeguard the brain, which the skull protects. Within the skull, the brain is covered by cranial meninges, including the outermost layer, the dura mater, a thick and robust membrane of dense connective tissue. 
• The middle layer, called the arachnoid, is delicate and unique to mammals. 
• The innermost layer, the pia mater, is thin, transparent, and highly vascularized, firmly adhering to the brain's surface.

Brain

• The brain can be classified into three main regions: 

(i) Forebrain 

(ii) Midbrain 

(iii) Hindbrain

(i) Forebrain: The forebrain consists of the cerebrum, thalamus and hypothalamus.

(ii) Midbrain: It is a small part of the brain. The midbrain is located between the forebrain's diencephalon and the hindbrain's pons.  A canal called the Cerebral aqueduct/ Aqueduct of Sylvius passes through the midbrain.

(iii) Hindbrain: The hindbrain comprises pons, cerebellum and medulla (also called the medulla oblongata). 

3.0Is Neural Control and Coordination Important for NEET? 

• Yes, neural control and coordination are essential topics for NEET (National Eligibility cum Entrance Test). 
• This section covers crucial concepts related to the functioning of the nervous system, including the structure and functions of neurons, synapses, the central and peripheral nervous systems, and the mechanisms of reflex action. 
• Understanding these concepts is essential for answering questions related to physiology, as they form the basis of how organisms respond to stimuli and maintain homeostasis. 
• Mastery of this topic can help secure better scores in the biology section of the NEET exam.

4.0NEET Questions on Neural Control and Coordination

1. Which part of the brain is responsible for coordinating voluntary movements?

(a) Medulla oblongata                                                      (b) Hypothalamus

(c) Cerebellum                                                                  (d) Thalamus

Answer: (c) Cerebellum

2.  The gap between two neurons is called:

(a) Synapse                                                                        (b) Dendrite

(c) Axon                                                                            (d) Myelin sheath

Answer: (a) Synapse

3. Which of the following neurotransmitters is primarily associated with the sympathetic nervous system?

(a) Acetylcholine                                                              (b) Dopamine

(c) Serotonin                                                                     (d) Norepinephrine

Answer:(d) Norepinephrine

4. Which of the following is NOT a function of the medulla oblongata?

 (a) Regulating heart rate                                                  (b) Controlling breathing

 (c) Coordinating balance and posture                              (d) Regulating blood pressure

Answer: (c) Coordinating balance and posture

5. The part of the neuron that receives signals from other neurons is called:

 (a) Axon                                                                           (b) Soma

 (c) Dendrite                                                                      (d) Synaptic terminal

Answer: (c) Dendrite

5.0NCERT Questions on Neural Control and Coordination

1. When a neuron is not conducting any impulse i.e. resting, the axonal membrane is-

(1) Comparatively more permeable to K+ and impermeable (nearly impermeable) to Na+ 

(2) Impermeable to negatively charged proteins present in the axoplasm 

(3) (1) & (2) both 

(4) More permeable to Na+ ions than K+ ion

2. Pick out the incorrect statement? 

(1) Myelinated nerve fibres are found in the spinal and cranial nerve. 

(2) Unmyelinated nerve fibre is enclosed by a schwann cell. 

(3) In the resting stage the axonal membrane is comparatively more permeable to potassium ion and nearly impermeable to sodium ions. 

(4) Axolemma is more permeable to negatively charged proteins present in the axoplasm.

3. Identify the correct set of statements : 

(a) Limbic lobe consists of amygdala and pons. 

(b) Cerebral aqueduct passes through the midbrain. 

(c) The medulla contains centers which control respiration, cardiovascular reflexes and gastric secretions. 

(d) Brain stem forms the connections between the cerebrum and midbrain. 

(e) Knee jerk reflex is a polysynaptic reflex. Choose the correct answer from options given below : 

(1) (a) and (d) only 

(2) (b), (c), (d) and (e) only 

(3) (a), (b), (d) and (e) only 

(4) (b) and (c) only

4. The name of nervous band connecting the cerebral hemispheres is - 

(1) Corpus albicans 

(2) Corpus callosum 

(3) Corpus striatum 

(4) Corpus spongiosum