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Feb 16, 2024 · Physicists found that the music of Johann Sebastian Bach contains mathematical patterns that help convey information. Bach's prelude for klavier score. Baroque German composer Johann Sebastian ...
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Sep 23, 2020 · One popular view is that mathematics is merely a set of rules, built up from a set of initial assumptions—what mathematicians call axioms. Once the axioms are in place, a vast array of logical ...
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What is an organ system?
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Jul 18, 2022 · Rules: In order for the division of S to be fair, the players in the game must be willing participants and accept the rules of the game as binding. The players must act rationally according to their system of beliefs. The rules of mathematics apply when assigning values to the objects in S. Only the players are involved in the game, there are ...
- Math allows biologists to describe how molecules move in and out of cells, how bacteria shuttle through blood vessels, how drugs get broken down in the body and many other physiological processes.
- Studying the geometry, topology and other physical characteristics of DNA, proteins and cellular structures has shed light on their functions and on approaches for enhancing or disrupting those functions.
- Math helps scientists design their experiments, including clinical trials, so they result in meaningful data, a.k.a statistical significance.
- Scientists use math to piece together all the different parts of a cell, an organ or an entire organism to better understand how the parts interact and how perturbations in these complex systems may contribute to disease.
- Overview
- Key points
- Introduction
- Multicellular organisms need specialized systems
- Overview of body organization
- Types of tissues
- Epithelial tissue
- Connective tissue
- Muscle tissue
- Nervous tissue
Learn about the main tissue types and organ systems of the body and how they work together.
•Humans—and other complex multicellular organisms—have systems of organs that work together, carrying out processes that keep us alive.
•The body has levels of organization that build on each other. Cells make up tissues, tissues make up organs, and organs make up organ systems.
•The function of an organ system depends on the integrated activity of its organs. For instance, digestive system organs cooperate to process food.
•Humans—and other complex multicellular organisms—have systems of organs that work together, carrying out processes that keep us alive.
•The body has levels of organization that build on each other. Cells make up tissues, tissues make up organs, and organs make up organ systems.
•The function of an organ system depends on the integrated activity of its organs. For instance, digestive system organs cooperate to process food.
•The survival of the organism depends on the integrated activity of all the organ systems, often coordinated by the endocrine and nervous systems.
If you were a single-celled organism and you lived in a nutrient-rich place, staying alive would be pretty straightforward. For instance, if you were an amoeba living in a pond, you could absorb nutrients straight from your environment. The oxygen you would need for metabolism could diffuse in across your cell membrane, and carbon dioxide and other wastes could diffuse out. When the time came to reproduce, you could just divide yourself in two!
However, odds are you are not an amoeba—given that you're using Khan Academy right now—and things aren’t quite so simple for big, many-celled organisms like human beings. Your complex body has over 30 trillion cells, and most of those cells aren’t in direct contact with the external environment.1 A cell deep inside your body—in one of your bones, say, or in your liver—can’t get the nutrients or oxygen it needs directly from the environment.
Most cells in large multicellular organisms don't directly exchange substances like nutrients and wastes with the external environment, instead, they are surrounded by an internal environment of extracellular fluid—literally, fluid outside of cells. The cells get oxygen and nutrients from this extracellular fluid and release waste products into it. Humans and other complex organisms have specialized systems that maintain the internal environment, keeping it steady and able to provide for the needs of the cells.
Different systems of the body carry out different functions. For example, your digestive system is responsible for taking in and processing food, while your respiratory system—working with your circulatory system—is responsible for taking up oxygen and getting rid of carbon dioxide. The muscular and skeletal systems are crucial for movement; the reproductive system handles reproduction; and the excretory system gets rid of metabolic waste.
All living organisms are made up of one or more cells. Unicellular organisms, like amoebas, consist of only a single cell. Multicellular organisms, like people, are made up of many cells. Cells are considered the fundamental units of life.
The cells in complex multicellular organisms like people are organized into tissues, groups of similar cells that work together on a specific task. Organs are structures made up of two or more tissues organized to carry out a particular function, and groups of organs with related functions make up the different organ systems.
As we saw above, every organ is made up of two or more tissues, groups of similar cells that work together to perform a specific task. Humans—and other large multicellular animals—are made up of four basic tissue types: epithelial tissue, connective tissue, muscle tissue, and nervous tissue.
Epithelial tissue consists of tightly packed sheets of cells that cover surfaces—including the outside of the body—and line body cavities. For instance, the outer layer of your skin is an epithelial tissue, and so is the lining of your small intestine.
Epithelial cells are polarized, meaning that they have a top and a bottom side. The apical, top, side of an epithelial cell faces the inside of a cavity or the outside of a structure and is usually exposed to fluid or air. The basal, bottom, side faces the underlying cells. For instance, the apical sides of intestinal cells have finger-like structures that increase surface area for absorbing nutrients.
Connective tissue consists of cells suspended in an extracellular matrix. In most cases, the matrix is made up of protein fibers like collagen and fibrin in a solid, liquid, or jellylike ground substance. Connective tissue supports and, as the name suggests, connects other tissues.
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.
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, cardiac muscle, and smooth 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!—you don’t need to think about making your heart beat. The individual fibers are connected by structures called intercalated disks, which allow them to contract in sync.
Nervous tissue is involved in sensing stimuli—external or internal cues—and processing and transmitting information. It consists of two main types of cells: neurons, or nerve cells, and glia.
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.
Cross Sections. A cross section is the shape we get when cutting straight through an object. The cross section of this object is a triangle. It is like a view into the inside of something made by cutting through it. This is a cross-section of a piece of celery.
The human body is a complex system made up of interacting parts. These parts include organ systems, organs, tissue, and cells. Cells in the human body are specialized. This means that they have unique structures and functions. A tissue is a group of similar, specialized cells. A tissue’s cells work together so that the tissue can do its job.
