BBC Bitesize - National 4 Biology - The difference between cells, tissues and organs
Ecological scientists study organism-environment interactions across . Early life arose in aquatic ecosystems, and all living cells still require water to function. such as coevolved relationships between specialized pollinators and flowers. Multicellular organisms have trillions of cells that work together. Biologists refer to the relationship between cells, tissues and organs as the. The smallest 'unit' are cells. There a So if there are no cells, no tissues, organs or any organ systems can form. Related Biology GCSE answers.
Factors that affect birth and death rates and therefore population growth can be dependent on or independent of population density the number individuals in an amount of space. Density dependent factors lead to repeating cycles in population size. Principles of population ecology are used extensively in the management of wildlife. Hunting seasons, catch limits, size restrictions, and quotas used for fish, seafood, and game are all ways in which governments of the world promote healthy and sustainable population sizes for these organisms.
Learn how populations grow and are limited in this resource from Mr. Niche represents the sum total of all the ways it utilizes resources in its environment: If two species share the same or a similar niche, they will both compete for the same resources and the worst competitor will be driven to extinction in that area.
This is called competitive exclusion. Habitats that are more complex in food sources, prey refuges, soil substrates, etc. Energy Flow The beginning teacher describes and analyzes energy flow through various types of ecosystems.
Ecosystems include autotrophs organisms, such as plants, that manufacture their own food from external sources of energy and heterotrophs consumers, such as animals, fungi and many protists. Once energy enters an ecosystem, it is passed from one organism to another by ingestion as food or decomposition.
Primary producers convert light energy or, rarely energy from chemosynthesis, into chemical bonds. Consumers rely on producers for their energy sources. All food chains begin with producers, followed by primary consumers, secondary consumers and tertiary consumers. Energy Flow through Ecosystems Energy flow in marine and terrestrial ecosystems is discussed in this resource from The Habitable Planet.
Tissues, organs, & organ systems
Loose connective tissue, show below, is the most common type of connective tissue. It's found throughout your body, and it supports organs and blood vessels and links epithelial tissues to the muscles underneath. Dense, or fibrous, connective tissue is found in tendons and ligaments, which connect muscles to bones and bones to each other, respectively. Specialized forms of connective tissue include adipose tissue—body fat—bone, cartilage, and bloodin which the extracellular matrix is a liquid called plasma.
Muscle tissue Muscle tissue is essential for keeping the body upright, allowing it to move, and even pumping blood and pushing food through the digestive tract.
Muscle cells, often called muscle fibers, contain the proteins actin and myosin, which allow them to contract. There are three main types of muscle: Skeletal muscle, which is also called striated—striped—muscle, is what we refer to as muscle in everyday life.
Skeletal muscle is attached to bones by tendons, and it allows you to consciously control your movements. For instance, the quads in your legs or biceps in your arms are skeletal muscle.
Cardiac muscle is found only in the walls of the heart. Like skeletal muscle, cardiac muscle is striated, or striped. But it's not under voluntary control, so—thankfully!
The individual fibers are connected by structures called intercalated disks, which allow them to contract in sync. Smooth muscle is found in the walls of blood vessels, as well as in the walls of the digestive tract, the uterus, the urinary bladder, and various other internal structures.
Smooth muscle is not striped, striated, and it's involuntary, not under conscious control. That means you don't have to think about moving food through your digestive tract! Nervous tissue Nervous tissue is involved in sensing stimuli—external or internal cues—and processing and transmitting information. It consists of two main types of cells: The neurons are the basic functional unit of the nervous system.
They generate electrical signals called conducted nerve impulses or action potentials that allow the neurons to convey information very rapidly across long distances. The glia mainly act to support neuronal function. Organs Organs, such as the heart, the lungs, the stomach, the kidneys, the skin, and the liver, are made up of two or more types of tissue organized to serve a particular function. For example, the heart pumps blood, the lungs bring in oxygen and eliminate carbon dioxide, and the skin provides a barrier to protect internal structures from the external environment.
Most organs contain all four tissue types. The layered walls of the small intestine provide a good example of how tissues form an organ.
The inside of the intestine is lined by epithelial cells, some of which secrete hormones or digestive enzymes and others of which absorb nutrients. Around the epithelial layer are layers of connective tissue and smooth muscle, interspersed with glands, blood vessels, and neurons.
The smooth muscle contracts to move food through the gut, under control of its associated networks of neurons.
How Are Cells, Tissues & Organs Related? | Sciencing
For example, the heart and the blood vessels make up the cardiovascular system. They work together to circulate the blood, bringing oxygen and nutrients to cells throughout the body and carrying away carbon dioxide and metabolic wastes. Another example is the respiratory system, which brings oxygen into the body and gets rid of carbon dioxide. It includes the nose, mouth, pharynx, larynx, trachea, and lungs. Major organ systems of the human body Organ system Organs, tissues, and structures involved Cardiovascular Transports oxygen, nutrients, and other substances to the cells and transports wastes, carbon dioxide, and other substances away from the cells; it can also help stabilize body temperature and pH Heart, blood, and blood vessels Lymphatic Defends against infection and disease and transfers lymph between tissues and the blood stream Lymph, lymph nodes, and lymph vessels Digestive Processes foods and absorbs nutrients, minerals, vitamins, and water Mouth, salivary glands, esophagus, stomach, liver, gallbladder, exocrine pancreas, small intestine, and large intestine Endocrine Provides communication within the body via hormones and directs long-term change in other organ systems to maintain homeostasis Pituitary, pineal, thyroid, parathyroids, endocrine pancreas, adrenals, testes, and ovaries.
Although we often talk about the different organ systems as though they were distinct, parts of one system may play a role in another system. The mouth, for instance, belongs to both the respiratory system and the digestive system. There's also a lot of functional overlap among the different systems. For instance, while we tend to think of the cardiovascular system as delivering oxygen and nutrients to cells, it also plays a role in maintaining temperature.
The blood also transports hormones produced by the glands of the endocrine system, and white blood cells are a key component of the immune system.
Organs in a system work together.
Just like workers on an assembly line, the organs of an organ system must work together for the system to function as a whole. For instance, the function of the digestive system—taking in food, breaking it down into molecules small enough to be absorbed, absorbing it, and eliminating undigested waste products—depends on each successive organ doing its individual job.