Nervous System and Synapses

Nervous System

• The human nervous system has two main parts: the central nervous system (CNS) and the peripheral nervous system.
• The CNS consists of the brain and spinal cord.
• The peripheral nervous system consists of nerves that branch out from the brain and spinal cord.

Brain

• The brain is protected by hard, bony structures and has four major features that help protect it from injury.
• The brain performs higher functions such as interpreting touch, vision, and hearing, as well as speech, reasoning, emotions, learning, and fine control of movement.

Cerebrum

• The cerebrum is the largest part of the brain and is divided into two hemispheres.
• The hypothalamus is the center for homeostatic control of the internal environment and regulates thirst, appetite, and body temperature.

Cerebellum

• The cerebellum is located under the occipital lobe and is separated from the brain stem by the fourth ventricle.
• It receives sensory input from the eyes, ears, joints, and muscles about the present position of body parts.

Brain Stem

• The brain stem connects the cerebrum to the spinal cord and consists of the midbrain, pons, and medulla oblongata.
• The midbrain acts as a relay station for tracts passing between the cerebrum and the spinal cord or cerebellum.
• The pons contains bundles of axons traveling between the cerebellum and the rest of the CNS.

Sensory Receptors

• Sensory receptors are nerve endings that can sense stimuli, such as pressure, pain, temperature, and start a nerve impulse.

Synapses

• Special types of synapses include neuromuscular junctions, which play a crucial role in the transmission of nerve impulses to muscles.

Neurotransmitters

• Neurotransmitters are chemical messengers that transmit signals between neurons and play a crucial role in the nervous system.

Eye

• The eye has a pupil that changes size in response to light intensity.
• The pupil constricts in bright light and dilates in low light.

Ear

• The ear is divided into three regions: the outer ear, middle ear, and inner ear.
• The outer ear consists of a flap called a pinna (auricle).
• The middle ear contains the eardrum and the inner ear contains the cochlea and semicircular canals.

Eye Defects

• Types of human eye defects include cataracts and glaucoma, which can be resolved with medical treatment.

Traditional Mechanisms

• Traditional mechanisms used to regulate body homeostasis in different localities may vary, and discussing these mechanisms in small groups can help identify unique approaches to maintaining body equilibrium.