Human Nervous, Skeletal and Reproductive Systems: Structure and Function

Nervous System

The nervous system is responsible for receiving, interpreting and responding to internal and external stimuli. It transmits nerve impulses through specialized neurons that carry signals throughout the body.

Central Nervous System

• Encephalon: formed by the brain, which controls intelligence and memory.
• Cerebellum: regulates muscular activity and coordination.
• Medulla Oblongata: controls vital functions such as breathing and heartbeat.
• Spinal Cord: receives sensory information and transmits motor responses.

Peripheral Nervous System

• Cranial Nerves: conduct stimuli to and from the brain.
• Spinal Nerves: transmit responses to the body.
• Somatic Nervous System: voluntary and reflex actions.
• Autonomic Nervous System:
  • Sympathetic System: prepares the body for emergencies and stress.
  • Parasympathetic System: promotes relaxation and normal bodily functions.

Sense Organs

Sense organs contain specialized receptors that detect stimuli such as light, sound, smell, taste and touch.

Endocrine System

The endocrine system coordinates chemical reactions that maintain the internal balance of the body through hormones secreted by the endocrine glands, regulated by the hypothalamus.

• Pituitary Gland: controls the activity of the other endocrine glands.
• Thyroid: produces thyroxine, which regulates metabolism.
• Pancreas: produces insulin, which allows glucose to pass from the blood into the cells.
• Gonads: determine the sexual characteristics of the individual.
• Suprarenal Glands: release adrenaline to prepare the body to face dangerous situations.
• Parathyroid Glands: maintain calcium absorption in the body.

Locomotor System

Skeletal System: passive hard parts of the apparatus: bone, cartilage, ligaments and tendons.

Muscular System: active or contractile parts of the apparatus: muscles.

Bone and Cartilage Tissue

• Bone Tissue: cells include osteoblasts, osteocytes and osteoclasts.
• Cartilage Tissue: cells include chondroblasts and chondrocytes.

Long Bones

• Epiphysis: contains red bone marrow, which produces blood cells.
• Diaphysis: contains yellow bone marrow rich in lipids.
• Periosteum: allows growth in length from the epiphyseal cartilage.

Axial Skeleton

• Skull: frontal, occipital, parietal, temporal, ethmoid and sphenoid bones.
• Face: maxilla, mandible, nasal, lacrimal, vomer and palatine bones.
• Vertebral Column: cervical (7), thoracic (12), lumbar (5), sacral (5) and coccygeal (4) vertebrae.
• Ribs: 12 pairs (14 sternal ribs, 6 false ribs and 4 floating ribs in total, as applicable).
• Sternum: sternum bone of the thorax.

Appendicular Skeleton

• Pectoral Girdle: clavicles and scapulae (shoulder blades).
• Upper Limbs: humerus, ulna, radius, carpals, metacarpals and phalanges.
• Pelvic Girdle: hip bones (ilium, ischium and pubis).
• Lower Limbs: femur, patella, tibia, fibula, tarsals, metatarsals and phalanges.

Function of Muscles

Muscle Function: muscles are made up of contractile tissue able to contract. Muscle cells are called muscle fibers.

Reproduction

Reproduction: allows the generation of new individuals who grow, develop and intervene in the male and female reproductive systems.

• Testes: spermatogenesis
• Ovaries: oogenesis