Human Nervous and Reproductive Systems: Functions and Anatomy
The Nervous System
The nervous system is responsible for perceiving, interpreting, and emitting responses in the face of internal and external stimuli. It has two parts:
- Central Nervous System (CNS): Consists of the brain and spinal cord. It receives information from outside and inside the body, integrates it, and decides the response to be given. It is protected by three protective membranes called meninges: the dura mater, arachnoid, and pia mater.
- Peripheral Nervous System: Formed by motor nerves (which carry information from the CNS to the muscles and glands) and sensory nerves (which carry information from sensory receptors to the CNS). These nerves connect the central nervous system to the different body parts.
Brain
The brain, protected inside the skull, is divided into:
- Brain: This is the most voluminous part and houses memory, intelligence, and consciousness.
- Cerebellum: Located below the brain, this section has a tree-like appearance and regulates muscle activity.
- Brainstem: Connects the brain with the spinal cord. It controls automatic functions like breathing and heartbeat.
Spinal Cord
Spinal cord: This is a nervous axis that originates at the base of the brain and runs along the dorsal trunk, protected inside the spine. Motor and sensory nerves leave from the spinal cord to almost the entire body. It can generate movements without brain interference, known as reflex movements.
Types of Nervous System Responses
- Somatic Nervous System: Regulates voluntary responses in which the effector muscles act. It requires a decision that is made in the brain, and the individual is aware of the stimulus received and the response issued.
- Reflex Arc: An involuntary response that is very fast and elaborated in the spinal cord, not involving the brain.
Diseases related to the nervous system include Parkinson’s disease, multiple sclerosis, Alzheimer’s disease, and depression.
Neurons
Neurons are specialized cells in the transmission of nerve impulses. They can be:
- Sensory: If the impulse is transmitted from the nerve receptors to other nerves.
- Motor: If the transmission is from the nerve centers to the effectors of a body.
Neurons are elongated and consist of a cell area where the cytoplasm and the nucleus are located. From one end extends a long axon, and from the other end, several short extensions called dendrites emerge. Both the axon and dendrites branch into their endpoints.
The Organs of the Senses
The organs of the senses: Sensory receptors are formed by cells specialized in capturing stimuli and generating nerve impulses transmitted through nerve neurons.
- Sense of Taste: Taste is the sense that allows us to detect liquids or substances dissolved in our saliva.
- Sense of Hearing and Balance: Located in the inner ear and formed by mechanoreceptors.
- Sense of Sight: Located in the retina of the eye and consists of photoreceptors.
- Sense of Touch: Located in the skin and formed by mechanoreceptors, thermoreceptors, and pain receptors.
The Male Reproductive System
The male reproductive system functions in the production of male gametes or sperm and their transmission to the female reproductive tract.
- Testes: Two egg-shaped bodies, 4cm in length, that produce sperm and secrete the hormone testosterone. Testosterone is responsible for the deep voice, broad shoulders, beard, etc.
- Vas Deferens: Two ducts that connect the testes with the seminal vesicles.
- Accessory Glands: Glands that contribute to semen production.