Circulatory Systems: Human and Vertebrate Blood Flow
There are two types of circulatory systems:
Closed circulatory system: It consists of a series of blood vessels through which the blood travels continuously. Materials carried by the blood reach the tissues through diffusion. It is characteristic of annelids, cephalopods, and vertebrates.
Open circulatory system: The blood pumped by the heart travels through blood vessels, which supply blood directly to the cells, returning by different mechanisms. This type of system is present in arthropods and
Read MoreHuman Reproduction and Development Stages
Human Reproduction
Females produce female gametes (eggs) and males produce male gametes (sperm). These two cells join to form a zygote.
Internal Fertilization
The egg and sperm unite in the female’s reproductive tract, and the new human being develops there.
Reproduction Steps
- Gamete Production: Specialized reproductive organs produce gametes.
- Fertilization: The union of both gametes inside the female reproductive tract forms the zygote.
- Zygote Development: Within the female reproductive tract, the zygote
Understanding the Human Nervous System: Structure and Function
The Nervous System: Receiving and Responding to Stimuli
The nervous system receives and responds to stimuli, maintaining the body’s homeostasis. It coordinates the activities of tissues, organs, and systems.
Neurons: The Building Blocks
Neurons are the primary cells responsible for transmitting nerve impulses. They consist of:
- Cell Body: Contains the nucleus and cytoplasm.
- Dendrites: Short, numerous extensions that capture nerve impulses.
- Axon: A long extension that conducts impulses to distant areas,
Understanding Plant Stems: Structure, Growth, and Function
Plant Stems: Structure, Growth, and Function
Introduction
Stems are integral parts of vascular plants, responsible for supporting leaves, flowers, and fruits. They facilitate the transport of water and nutrients between roots and leaves, and also play a role in storage. Stems can be epigean (above ground) or subterranean (below ground).
Stem Origin and Development
Stems originate from the plumule within the seed embryo. The plumule contains the initial bud or apical meristem, which drives stem growth.
Read MoreHuman Reproductive System and Menstrual Cycle
Male and Female Reproductive Systems
Female Reproductive System
- Gametes are produced and delivered.
- Male and female gametes each carry one ‘half-set’ of genetic information in their nuclei.
- One male and one female gamete join together.
- A zygote is formed when the male and female nuclei fuse. This is fertilization. The zygote has one ‘complete set’ of genetic information.
- The zygote divides many times to produce a large number of cells.
- The embryo is formed when the cells begin to take up the positions
Understanding Transplantation and Autoimmune Diseases
Transplantation Types
When the donor and recipient are the same individual, it is referred to as autologous, autograft, or autologous transplantation. This is mainly used for tissues like skin, bone, vessels, or bone marrow.
Isotransplant
When the donor and recipient are identical twins. Since both individuals are genetically identical, this completely avoids the problem of rejection.
Allogeneic or Homograft
When the donor and recipient are members of the same species but not genetically identical. This
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