Human Nervous, Musculoskeletal, and Endocrine Systems
In vertebrates, the NERVOUS SYSTEM consists of:
Nervous Centers
- Brain and spinal cord. Responsible for receiving, processing, and developing responses to sensory information.
Nerve Fibers
- These are the axons of neurons. Responsible for getting sensory stimuli to the nerve centers and transmitting responses of the motor fibers.
Nerves
- Made by the union of nerve fibers.
Nodal Masses
- Clusters of neuronal bodies located along some nerve pathways.
Central Nervous System (CNS)
The CNS is constituted from a large
Read MoreInvertebrate Biology: Annelids, Mollusks, Arthropods
Leaf Structure
Plants faced dehydration when transitioning to land. Photosynthesis requires light and CO2. Leaf structure adapted to solve this. Angiosperm leaves have architectural adaptations to avoid desiccation. Upper and lower surfaces are covered with transparent epidermal cells coated with a waxy cuticle, reducing water loss. Between is the mesophyll, including palisade cells (columnar, below upper epidermis) for photosynthesis. Lacunar mesophyll (loosely arranged cells with spaces) also aids
Read MoreHuman Biology: Auditory, Visual, Olfactory, Gustatory & Tactile Senses
Organs
Auditory System
The ear consists of three parts: the outer ear, middle ear, and inner ear.
Outer Ear
Composed of the pinna, ear canal, and eardrum, the outer ear collects and transmits sound waves to the middle ear. The ear canal contains small hairs and wax-producing glands for protection. The eardrum is a membrane separating the outer and middle ear.
Middle Ear
This section contains the tympanic cavity with three openings: one closed by the eardrum, and two inward openings called the oval window
Read MoreDisease Classification and Etiology
Disease Classification
Genetic Diseases
These diseases arise from modifications in the genome. Hereditary diseases occur when these modifications are passed down through generations. If the alteration is on a sex chromosome, it results in a sex-linked inherited disease, typically affecting only one sex. Mitochondrial inherited diseases involve modifications in mitochondrial DNA, always originating from the mother.
Degenerative Diseases
These involve impaired regenerative ability. Sometimes, the body
Read MoreConnective Tissue: Cells, Fibers, and Functions
Connective Tissue
Derived from the mesenchyme, embryonic star-shaped cells establish contact through cytoplasmic extensions, forming a lattice structure. Mesenchyme originates from two tissue groups:
- Connective, cartilage, and bone tissues.
- Blood and hematopoietic tissues.
Connective Tissue Composition
Connective tissue comprises cells and fibers within a fundamental and immigrant substance.
Connective Tissue Cells
Connective tissue cells are numerous and varied, divided into two groups:
Fixed Cells
These
Read MoreOrigins and Evolution of Life: A Comprehensive Overview
1. Main Ideas About the Origin of Life
Several key ideas address the origin of life:
- Creationism
- Spontaneous Generation
- Panspermia
- Evolutionary Theories
2. Creationism
Creationism posits a divine origin for life. It is not considered a scientific theory because it is not based on observable evidence and cannot be tested.
3. Spontaneous Generation
This idea suggests that living beings could arise from non-living matter.
4. Scientists Who Disproved Spontaneous Generation
Louis Pasteur and Francesco Redi designed
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