Chapter 3 Cells

1. Chapter 3Cells

2. A Typical Cell • The cell is the structural and functional unit of all living matter.

3. A Typical Cell - cont’d • Cell Membrane (Plasma Membrane) • The cell membrane is composed of a two-layer phospholipid and protein. • The cell membrane is selectively permeable.

4. A Typical Cell - cont’d • Structures Inside the Cell • The nucleus is the control center of the cell; it stores the genetic information. • The cytoplasm is a gel-like substance inside the cell membrane but outside of the nucleus. • Many different organelles are in the cytoplasm. • The mitochondria are the power plants of the cell. • Ribosomes are concerned with protein synthesis.

5. A Typical Cell - cont’d • Structures Inside the Cell—cont’d • The Golgi apparatus packages and puts the finishing touches on the newly synthesized protein. • Lysosomes act as intracellular housekeepers. • The cytoskeleton provides shape and support to the cell. • Centrioles play a role in cell reproduction.

6. A Typical Cell - cont’d • Structures on the Cell Membrane • Cilia are short, hairlike projections. • Flagella are long, hairlike projections; the sperm has a flagellum that allows it to swim.

7. Movement Across the Cell Membrane • Passive Transport Mechanisms • Passive transport mechanisms require no input of energy (ATP). • Diffusion is the movement of a substance from an area of greater concentration to an area of lesser concentration. • Facilitated diffusion is the same as diffusion but uses a helper molecule to increase the rate of diffusion.

8. Movement Across the Cell Membrane - cont’d • Passive Transport Mechanisms—cont’d • Osmosis is a special case of diffusion using a semipermeable membrane. Osmosis involves the diffusion of water from an area with more water to an area of less water. The concentrations of a solution are expressed as tonicity. Solutions are isotonic, hypotonic, or hypertonic. • Filtration is the movement of water and dissolved substances from an area of high pressure to an area of low pressure.

9. Movement Across the Cell Membrane - cont’d • Active Transport Mechanisms • Active transport requires an input of energy (ATP). • Active transport pumps move substances from an area of low concentration to an area of high concentration. • Endocytosis moves substances into a cell; pinocytosis is cellular “drinking,” and phagocytosis is cellular “eating.” • Exocytosis moves substances out of a cell.

10. Cell Division • Mitosis: produces two identical cells • Meiosis: occurs only in sex cells

11. Cell Cycle • Interphase (G1, S, and G2 phases) • Mitosis (M phase) • The splitting of one mother cell into two identical daughter cells. • Four phases of mitosis: prophase, metaphase, anaphase, and telophase. • Cell Cycle–Phase Specific Drugs • Some drugs are aimed at a specific phase of the cell cycle. • Some are cell cycle–phase nonspecific.

12. Cell Differentiation

13. Stem Cells

14. Order, Disorder, and Death

15. Introduction • Our bodies are made of different chemicals. To understand the body, you need to understand some general chemical principles.

16. Matter, Elements, and Atoms • Matter • Matter is anything that occupies space and has weight. • Matter exists in three states: solid, liquid, and gas. • Matter can undergo physical and chemical changes.

17. Matter, Elements, and Atoms - cont’d • Elements • An element is a fundamental substance that cannot be broken down into a simpler form by ordinary chemical means. • Four elements (carbon, hydrogen, oxygen, and nitrogen) make up 96% of the body weight.

18. Matter, Elements, and Atoms - cont’d • Atoms • An atom is the basic unit of matter. • An atom is composed of three subatomic particles: neutrons, protons, and electrons. • The atomic number: the number of protons. • The atomic weight: the number of neutrons and protons. • An isotope is an atom with the same atomic number but a different atomic weight. A radioisotope is an unstable isotope.

19. Chemical Bonds • Electron Shells and Bonding • Each electron shell holds a specific number of electrons. • Ionic bonds are formed as electrons are transferred to stabilize the shells of the atoms. • Covalent bonds are formed as the electrons of the outer shells are shared by the interacting atoms. • Hydrogen bonds are intermolecular bonds.

20. Chemical Bonds - cont’d • Ion Formation • An ion is an atom that carries an electrical charge. A cation is a positively charged ion. An anion is a negatively charged ion. • An electrolyte is a substance that forms ions when dissolved in water.

21. Chemical Bonds - cont’d • Molecules and Compounds • A molecule is a substance formed by two or more atoms (O2, H2O). • A compound is a substance that forms when two or more different atoms bond (H2O). • Important molecules and compounds include water, oxygen, and carbon dioxide.

22. Chemical Bonds - cont’d • Acids and Bases • An acid is an electrolyte that dissociates into a hydrogen ion (H+) and an anion. • A base is a substance that combines with H+ and eliminates H+; a base neutralizes an acid by producing a salt and water. • The pH scale measures acidity and alkalinity. A pH of 7 is neutral. A pH less than 7 is acidic, and a pH greater than 7 is basic, or alkaline.

23. Chemical Bonds - cont’d • Acids and Bases—cont’d • The normal pH of the blood is 7.35 to 7.45. A person with a pH less than 7.35 is acidotic, and a person with a pH greater than 7.45 is alkalotic. • Blood pH is regulated by buffers, the respiratory system, and the kidneys.

24. Energy • Definition: the ability to do work. • Forms of Energy • The six forms of energy: see Table 2-3. • Most energy is released as heat. • Role of Adenosine Triphosphate (ATP) • ATP is an energy-transfer molecule. • The energy is stored in high-energy phosphate bonds.

25. Mixtures, Solutions, and Suspensions • A mixture is a blend of two or more substances that can be separated by ordinary physical means. • Solutions, suspensions, and colloidal suspensions are types of mixtures.

26. Chapter 1Introduction to the Human Body

27. Introduction • Anatomy is the study of structure; physiology is the study of function.

28. The Body’s Levels of Organization • From Simple to Complex • The body is arranged from simple to complex. • Structure and function are related. • Major Organ Systems • An organ system is a group of organs that help each other to perform a particular function.

29. The Body’s Levels of Organization - cont’d • Major Organ Systems • There are 11 major organ systems. • The integumentary system • The skeletal system • The muscular system • The nervous system • The endocrine system • The circulatory system • The lymphatic system

30. The Body’s Levels of Organization - cont’d • Major Organ Systems • There are 11 major organ systems—cont’d. • The respiratory system • The digestive system • The urinary system • The reproductive system • Homeostasis refers to the body’s ability to maintain a stable internal environment in response to a changing external environment

31. Anatomical Terms: Talking About the Body • Anatomical Position • The anatomical position is the body standing erect, arms by the side, with palms facing forward. • Paired terms that describe direction include superior and inferior, anterior and posterior, medial and lateral, proximal and distal, superficial and deep, and central and peripheral. • The three planes are the sagittal plane, frontal (coronal) plane, and transverse plane. • Regional terms are listed in Figure 1-6.

32. Anatomical Terms: Talking About the Body - cont’d • Cavities of the Body • Dorsal cavity • The cranial cavity contains the brain. • The spinal cavity, or vertebral cavity, contains the spinal cord.

33. Anatomical Terms: Talking About the Body - cont’d • Ventral Cavity • The thoracic cavity is above the diaphragm and contains the lungs; it also contains the mediastinum. • The abdominopelvic cavity is located below the diaphragm. • The abdominal cavity is the upper part that contains the stomach, most of the intestines, liver, spleen, and kidneys. • The pelvic cavity is the lower part that contains the reproductive organs, urinary bladder, and lower part of the intestines. • For reference, the abdominopelvic cavity is divided into four quadrants and nine regions.