Human Blood: Components and Functions
Blood
The human body contains several extracellular fluids that constitute the internal environment. These include the interstitial fluid of the intercellular matrix and circulating fluids such as blood and lymph. These fluids act as intermediaries between the highly variable external environment and the intracellular environment, where metabolic reactions occur.
Blood is a liquid tissue, part of the internal environment, that circulates through blood vessels.
Blood performs a wide variety of functions:
Read MoreMollusk and Annelid Characteristics & Classes
Mollusks: Diverse Invertebrates
Mollusks are a diverse group of invertebrates, including snails, clams, squids, and octopuses. They have soft bodies, often protected by a shell, and exhibit a wide range of adaptations.
Mollusk Body Plan
- Head-foot: Includes the sensory organs and movement structures.
- Visceral mass: Contains internal organs like the heart, digestive system, and reproductive organs.
- Mantle: Secretes the shell and forms the mantle cavity, housing gills or lungs.
- Radula: A specialized feeding
Evolutionary Biology: Darwin, Wallace, and Evidence of Evolution
Evolution and Natural Selection
Evolution occurs through mutations. Individuals do not change; they pass changes to their offspring, leading to population change.
Alfred Russell Wallace and Darwin’s Contemporary
Alfred Russell Wallace was a naturalist who independently conceived the theory of natural selection, similar to Darwin’s. Although they corresponded by letters, they never met in person. Wallace’s contributions were not as widely recognized as Darwin’s for several reasons. Wallace mistakenly
Read MoreHuman Circulatory and Excretory Systems Explained
Blood Components and Function
Blood is a red liquid that circulates through blood vessels, carrying oxygen, nutrients, carbon dioxide, and collected waste products. It consists of plasma (55%) and blood cells (45%), totaling approximately 5 liters in the average adult.
Plasma Composition
Plasma is a yellowish liquid containing water, salts, minerals, hormones, and proteins.
Blood Cells: Types and Roles
Blood cells are formed in the bone marrow.
Red Blood Cells (Erythrocytes)
These are the most abundant
Read MoreDefining Life: Core Characteristics and Cellular Basis
Core Characteristics of Living Things
All living things share fundamental characteristics:
- Life Cycle: They have a life cycle that includes birth (origin) and death.
- Chemical Composition: They share a similar chemical composition, primarily based on organic matter.
- Cellular Structure: They are composed of one or more basic units called cells. Cells are the smallest microscopic units considered to be alive.
- Life Functions: They perform essential life functions:
Nutrition
Nutrition is the set of processes
Read MoreCirculatory Systems: Open vs. Closed & Vertebrate Hearts
Circulatory Systems: Open and Closed
Two main types of circulatory systems exist: open and closed. Both share three common elements:
- A fluid (in echinoderms, it’s called hydrolymph; in most invertebrates, hemolymph; and in vertebrates, blood and lymph).
- A network of blood vessels to carry the fluid.
- A heart, a muscular organ that pumps the fluid.
Open Circulatory System
Typical of arthropods and most mollusks (except cephalopods). Blood vessels don’t form a complete network; instead, blood drains into
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