In this review I will be covering the wide topic of cells. I will briefly touch on the topics of the Basic Characteristics of Life, how being alive means being composed of cells working together in mass units. Cells being comprised of many atoms are joined together to form molecules, which is another topic I will discuss in greater detail. I will also be reviewing the many different structures and functions of human cells including their size and components/organelles and the cells diverse functions in the body. Lastly I will review different tissue types, their make-up and functions in and on the body.
1. The seven basic characteristics of life are functions that all living things do or have the ability to do. The first is that we are organized in an intricate way, from the tiniest atom in our body all the way to the biosphere we are a part of. We all rely on the environment around us to provide necessary products for life. Basically in order to continue living, plants animals and humans must acquire food from elsewhere to provide energy and nutrients to stay healthy. Reproduction is another basic characteristic of life. Plants reproduce offspring similar to themselves by pollination. Mammals reproduce by fertilization. We all grow and develop from the time of conception to the time of death. This includes all the growth that occurs from the time of conception and also healing after damage has occurred to the body. We are all homeostatic meaning that our beings regulate our internal operations to adapt to the environment around us. All living things require certain internal operations to support their way of life. Being homeostatic means all systems of a life form working together to maintain homeostasis. We also react to stimuli, meaning that when external stimuli occur, internal systems kick in to react to those stimuli in an appropriate manner. And finally we have adapted to life as we know it. These characteristics define what being alive is.
2. Molecules are formed by atoms joining together to perform a specific function. Atoms can join together with atoms of the same type and also atoms of a different type. An ionic reaction occurs when two atoms with differing amounts of electrons combine, and one atom will give one or more electron to the other atom to achieve the desired outcome of 8 electrons in each atoms outer shell. This is seen in the bonding of the oppositely charged atoms sodium and chloride bonding together to make table salt. Covalent bonding in atoms occurs when the atoms share electrons.
Figure 1
Two examples of chemical bonds
Figure 1
Two examples of chemical bonds.
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One atom, such as an oxygen atom, may be lacking two electrons to have a stable outer shell. Therefore two hydrogen atoms, each with their own electron in the outer shell, will bond with the oxygen atom to produce a water molecule. Water molecules are crucial to life in every aspect. Water makes up about 60-70% of body weight and water allows life to continue as we know it. There are 4 categories of what are called molecules of life, Proteins, Lipids, Carbohydrates and nucleic acids. Carbohydrates are classified in two groups simple and complex. Both groups function as energy in organisms. Simple carbohydrates contain a lower amount of carbon atoms and glucose is a hexose (6 sided or 6 carbon) sugar/ carbohydrate. Complex carbohydrates contain many glucose units. Lipids are fats and used for energy storage. They serve this purpose well because they can hold more energy than the typical molecules. Proteins serve many purposes in cells, and therefore in the human body, some of those functions are in the forming of hair, nails etc. also transportation in the body such as hemoglobin in the blood which serves to transport oxygen. And contraction in the muscles is due to proteins presence. Nucleic acids are the last category of the molecules of life. Two types of nucleic acids are DNA and RNA. DNA serves as a blueprint for amino acids and proteins, RNA is the transmitter of the blueprint instructions.
3. A cells structure and function in the human body varies in many ways from how small they are to how they are internally organized. Smaller cells are more effective in many ways because they produce less waste than a large cell and they require less energy for survival. There are two types of cells prokaryotic and eukaryotic. Human cells are eukaryotic, containing a nucleus. The nucleus is where genetic information in the form of DNA is stored. The outer layer of a cell is called the plasma membrane. The plasma membrane is selectively permeable; it regulates what enters and exits the cell by diffusion, osmosis and facilitated transport. Also in the cell are energy makers called mitochondria. Mitochondria translate glucose into ATP (adenosine triphosphate). The process for making ATP is called cellular respiration. In cellular respiration there are three main pathways; glycolysis which begins the breakdown of glucose, the citric acid cycle finishes breaking the glucose down, and the electron transport chain finishes the cycle producing 32 ATP per glucose molecule. Inside the cell there is a semi fluid product called the cytoplasm that keeps all the organelles in place.
4. In the human body there are 4 main types of tissues. “A tissue is composed of specialized cells of the same type that perform a common function in the body.” The 4 main types of cells in the body are connective tissue, muscular tissue, nervous tissue and epithelial tissue. Connective tissues have 4 sub groups; fibrous, which is found in the internal organs and epithelium. Supportive connective tissue is found in cartilage. Bone is the hardest of the connective tissues. And finally fluid connective tissue, which are our blood and lymph (fluid that contains white blood cells). The second type of tissue is muscular tissue, which is what moves out bodies inside and out. The sub groups of muscular tissue are skeletal muscle, which moves the bones. Smooth muscle, which is located internally and is an involuntary muscle. And cardiac muscle contracts the heart. The third tissue is nervous tissue which is comprised of neurons. Neurons form nerves that in turn form the nervous system. The fourth tissue is epithelial tissue covers surfaces (skin) and lines cavities (lungs, internal organs, throat, intestines and trachea). Two or more tissue types grouping together to achieve a common goal is what is known as an organ. Organ systems are different organs collectively performing a common task. The following is a chart of the human body’s organ systems.
1. The seven basic characteristics of life are functions that all living things do or have the ability to do. The first is that we are organized in an intricate way, from the tiniest atom in our body all the way to the biosphere we are a part of. We all rely on the environment around us to provide necessary products for life. Basically in order to continue living, plants animals and humans must acquire food from elsewhere to provide energy and nutrients to stay healthy. Reproduction is another basic characteristic of life. Plants reproduce offspring similar to themselves by pollination. Mammals reproduce by fertilization. We all grow and develop from the time of conception to the time of death. This includes all the growth that occurs from the time of conception and also healing after damage has occurred to the body. We are all homeostatic meaning that our beings regulate our internal operations to adapt to the environment around us. All living things require certain internal operations to support their way of life. Being homeostatic means all systems of a life form working together to maintain homeostasis. We also react to stimuli, meaning that when external stimuli occur, internal systems kick in to react to those stimuli in an appropriate manner. And finally we have adapted to life as we know it. These characteristics define what being alive is.
2. Molecules are formed by atoms joining together to perform a specific function. Atoms can join together with atoms of the same type and also atoms of a different type. An ionic reaction occurs when two atoms with differing amounts of electrons combine, and one atom will give one or more electron to the other atom to achieve the desired outcome of 8 electrons in each atoms outer shell. This is seen in the bonding of the oppositely charged atoms sodium and chloride bonding together to make table salt. Covalent bonding in atoms occurs when the atoms share electrons.
Figure 1
Two examples of chemical bonds
Figure 1
Two examples of chemical bonds.
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One atom, such as an oxygen atom, may be lacking two electrons to have a stable outer shell. Therefore two hydrogen atoms, each with their own electron in the outer shell, will bond with the oxygen atom to produce a water molecule. Water molecules are crucial to life in every aspect. Water makes up about 60-70% of body weight and water allows life to continue as we know it. There are 4 categories of what are called molecules of life, Proteins, Lipids, Carbohydrates and nucleic acids. Carbohydrates are classified in two groups simple and complex. Both groups function as energy in organisms. Simple carbohydrates contain a lower amount of carbon atoms and glucose is a hexose (6 sided or 6 carbon) sugar/ carbohydrate. Complex carbohydrates contain many glucose units. Lipids are fats and used for energy storage. They serve this purpose well because they can hold more energy than the typical molecules. Proteins serve many purposes in cells, and therefore in the human body, some of those functions are in the forming of hair, nails etc. also transportation in the body such as hemoglobin in the blood which serves to transport oxygen. And contraction in the muscles is due to proteins presence. Nucleic acids are the last category of the molecules of life. Two types of nucleic acids are DNA and RNA. DNA serves as a blueprint for amino acids and proteins, RNA is the transmitter of the blueprint instructions.
3. A cells structure and function in the human body varies in many ways from how small they are to how they are internally organized. Smaller cells are more effective in many ways because they produce less waste than a large cell and they require less energy for survival. There are two types of cells prokaryotic and eukaryotic. Human cells are eukaryotic, containing a nucleus. The nucleus is where genetic information in the form of DNA is stored. The outer layer of a cell is called the plasma membrane. The plasma membrane is selectively permeable; it regulates what enters and exits the cell by diffusion, osmosis and facilitated transport. Also in the cell are energy makers called mitochondria. Mitochondria translate glucose into ATP (adenosine triphosphate). The process for making ATP is called cellular respiration. In cellular respiration there are three main pathways; glycolysis which begins the breakdown of glucose, the citric acid cycle finishes breaking the glucose down, and the electron transport chain finishes the cycle producing 32 ATP per glucose molecule. Inside the cell there is a semi fluid product called the cytoplasm that keeps all the organelles in place.
4. In the human body there are 4 main types of tissues. “A tissue is composed of specialized cells of the same type that perform a common function in the body.” The 4 main types of cells in the body are connective tissue, muscular tissue, nervous tissue and epithelial tissue. Connective tissues have 4 sub groups; fibrous, which is found in the internal organs and epithelium. Supportive connective tissue is found in cartilage. Bone is the hardest of the connective tissues. And finally fluid connective tissue, which are our blood and lymph (fluid that contains white blood cells). The second type of tissue is muscular tissue, which is what moves out bodies inside and out. The sub groups of muscular tissue are skeletal muscle, which moves the bones. Smooth muscle, which is located internally and is an involuntary muscle. And cardiac muscle contracts the heart. The third tissue is nervous tissue which is comprised of neurons. Neurons form nerves that in turn form the nervous system. The fourth tissue is epithelial tissue covers surfaces (skin) and lines cavities (lungs, internal organs, throat, intestines and trachea). Two or more tissue types grouping together to achieve a common goal is what is known as an organ. Organ systems are different organs collectively performing a common task. The following is a chart of the human body’s organ systems.
ORGAN SYSTEMS
1. Integumentary
Body covering. Skin, hair, nails, sweat glands.Function: protect underlying tissues and regulate body temperature
2. Skeletal
Bones, ligaments, cartilageFunction: Support, movement, protection, and production of blood cells
3. Muscular
Muscles of the bodyFunction: Movement, maintenance of posture, production of body heat
4. Nervous
Brain, spinal cord, nerves through the bodyFunction: Communication throughout body, mental activities, maintaining homeostasis
5. Endocrine
Ductless glands = pituitary, adrenal, thyroid, parathyroid, pancreas, ovaries, testes, thymus, pineal glandsFunction: Secretion of hormones, communication between body parts
6. Digestive
Mouth, teeth, pharynx, esophagus, stomach, small intestine, large intestine, liver, gall bladder, and many glands including the pancreasFunction: Breakdown of food substances into simpler forms that can be absorbed (digestion).
7. Circulatory
Heart, blood vessels, blood. Function: Transports materials throughout the body. *Lymphatic system usually included with the circulatory system
8. Urinary
Kidneys, ureters, urinary bladder, urethraFunction: Removes ("filters") wastes from the blood and helps maintain the body's water and electrolyte balance
9. Reproductive
Reproductive organs, primarily the ovaries (females) and testes (males)Function: Produce special reproductive cells for reproduction
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citations:
1. Mader, Sylvia S. Human Biology 10E. Janice Roerig-Blong 2008
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