Human Body Coordination: Nervous and Endocrine Systems
Coordination of the Human Body
The coordination of our body is achieved using two systems:
- The nervous system, which consists of:
- The central nervous system (brain and spinal cord) – receives and processes information to control body functions.
- The peripheral nervous system (composed of nerves that arrive at or depart from the central nervous system) – transforms messages from the central nervous system to organs and vice versa.
- The endocrine system
The Central Nervous System
Brain
The brain, cerebellum, and medulla oblongata form the brain. The brain appears divided into two hemispheres. The surface has convolutions called cisuras, formed by the outer gray matter and white matter internally. The brain processes and stores information.
Cerebellum
Located under the brain, the cerebellum is divided into two hemispheres. It coordinates movements such as walking and manipulating tools, and it allows us to maintain balance.
Medulla Oblongata
Linking the brain to the top of the spinal cord, the medulla oblongata controls blood vessel flow, respiratory movements, etc.
Spinal Cord
The spinal cord is housed inside the spinal column. Thirty-one pairs of spinal nerves start from it. It is also in charge of governing the so-called “reflex movements”.
The Peripheral Nervous System
- Sensory nerves carry information from sense organs and viscera to the central nervous system.
- Motor nerves carry commands from the central nervous system to muscles and organs responsible for carrying out the response.
Divisions of the Nervous System
- Somatic nervous system is responsible for voluntary acts such as writing or walking.
- Autonomic nervous system regulates the involuntary functioning of organs like the heart so that its activity is at all times accommodated to the needs of our bodies.
Neurons
Neurons are cells that communicate through synapses. The nerve impulses that neurons send are transmitted through these synapses. The cell body contains most of the cytoplasm and the extensions (dendrites). The axon, the longer extension, is surrounded by a myelin sheath. There is no physical contact between neurons, but they communicate through neurotransmitters, which are chemicals.
The Endocrine System
Endocrine Glands
Endocrine glands, such as the pituitary or thyroid glands, produce substances called hormones that are released into the blood.
Exocrine Glands
Exocrine glands, such as sweat, salivary, or liver, are not part of the endocrine system.
Important Endocrine Glands and Hormones
- Pituitary gland
- Growth hormone (somatotropin): stimulates the growth of our body.
- Thyrotropin: stimulates the secretion of the thyroid.
- ACTH: stimulates the secretion of the adrenal glands.
- Gonadotropin: regulates the activity of sex glands.
- Prolactin: stimulates milk secretion in women.
- Thyroid
- Thyroxine: stimulates the chemical activity of the cells.
- Adrenal glands
- Adrenaline: stimulates the heart and breathing rates.
- Testicles
- Testosterone: regulates the function of the male sex organs.
- Ovaries
- Progesterone and estradiol: regulate the development and functions of the female sexual organs and prepare the body for possible pregnancy.
Characteristics of Hormones
- Hormones are specific; each hormone acts on a particular target cell.
- They are very effective because a small amount is enough for them to fulfill their function.
- Their production is controlled; an excess or shortfall in the amount of a hormone can cause characteristic diseases.