Human Cell Organelles, Digestion, Respiration & Nervous System
Human Cell Organelles
Organelle from a human cell:
Mitochondria: Oval-shaped with a double membrane, providing energy.
Vacuoles: Membranous vesicles containing water, waste, and reserves.
Lysosomes: Transform complex substances into simpler ones.
Cytoskeleton: Filaments forming a network for cell structure and movement.
Centrioles: Hollow cylinders directing cytoskeleton movement.
Endoplasmic Reticulum: Sacs and canals for substance manufacturing.
- Smooth: No ribosomes.
- Rough: Ribosomes attached for protein
Understanding Skin and Nail Conditions: A Comprehensive Overview
1. Melanocytes:
• Originate from the neural crest.
• Found in the basal layer of keratinocytes.
• Large clear cytoplasm.
• Dendritic processes reaching the basal layer, spinous, and granulocytes.
• Melanosomes: melanin.
• Melanoepidermic unit: 1 melanocyte to 36 keratinocytes.
• Number is constant, independent of race or gender, but varies by body areas.
• Pigmentation depends on the size and distribution of melanin granules in keratinocytes.
• Affects skin, hair, and eyes.
•
Exploring the World of Cells
1. Cell Theory
– A cell is the structural unit of living things.
– A cell is the functional unit of living things. It performs all metabolic processes.
– Every cell comes from an existing one.
– A cell is the genetic unit of all living beings. It contains the hereditary material.
2. Types of Cellular Organization
– Prokaryotic cells: lack a nucleus. The genetic material is dispersed in the cytoplasm. Ex: bacteria.
– Eukaryotic cells: possess a nucleus containing the genetic material. Plants and animals
Read MoreUnderstanding Vertebrates: From Fish to Mammals
Vertebrates
Vertebrates have bilateral symmetry and are equipped with a skull that protects the brain and a cartilaginous or bony skeleton, including a vertebral column. The typical vertebra has the body clearly divided into three regions: head, trunk, and tail.
Chordata
Deuterostomia, bilateral symmetry, segmented body, triploblasty (three germ layers), well-developed coelom (lost in some groups).
Features:
- They have a hollow, tubular nerve cord, dorsal to the gut (epineurium). From this ridge, in more
Embryonic Development: From Zygote to Organism
Development: Zygote to Adult Organism
Development refers to the transformation of the zygote into an adult organism.
Segmentation
Segmentation is the set of cell divisions where a single cell or multicellular body produces a blastula. Initially, the zygote divides through mitosis, forming a compact mass of undifferentiated cells called blastomeres, known as a morula.
Cells reorganize, placing blastomeres around a central cavity called the blastocoel. This structure is the blastula stage of cell cleavage.
Read MoreAnimal Organization: From Cells to Systems
Animal Organization Hierarchy
All animal cells originate from a zygote, the result of fertilization between an ovum and a spermatozoon. Fertilization triggers changes in the zygote, preparing it for segmentation, DNA and protein synthesis, and cytoplasmic reorganization during embryonic development. The zygote undergoes a series of mitotic divisions. This development is characterized by the formation of infrastructure and the determination of different cell functions. Cells specialize into tissues,
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