Introduction to Human Anatomy and Physiology

Overview of Anatomy and Physiology

Anatomy and physiology are foundational sciences in understanding the structure and function of the human body. Anatomy focuses on the structure of living organisms, while physiology studies the function of these structures.

• Gross anatomy: Study of large body structures visible to the naked eye (e.g., heart, lungs, kidneys).

• Microscopic anatomy: Study of structures too small to be seen without magnification (e.g., cells, tissues).

• Developmental anatomy: Traces structural changes throughout the lifespan.

• Physiology: Study of the function of living organisms, including:

  • Renal physiology: Kidney function and urine production.

  • Neurophysiology: Functioning of the nervous system.

  • Cardiovascular physiology: Operation of the heart and blood vessels.

Levels of Structural Organization

The human body is organized into several levels, each building upon the previous:

• Chemical level: Atoms, molecules, and organelles.

• Cellular level: Cells, the basic unit of life.

• Tissue level: Groups of similar cells with a common function.

• Organ level: Contains two or more types of tissues.

• Organ system level: Organs that work closely together.

• Organismal level: The sum total of all structural levels working together to keep us alive.

Major Organ Systems of the Human Body

The body is composed of several organ systems, each with specific functions:

• Integumentary system: Skin, protects the body, synthesizes vitamin D, houses receptors and glands.

• Skeletal system: Provides framework, supports and protects organs, stores minerals.

• Muscular system: Allows movement, maintains posture, produces heat.

• Nervous system: Fast-acting control system, responds to internal and external changes.

• Endocrine system: Glands secrete hormones for regulation of growth, reproduction, metabolism.

• Cardiovascular system: Heart and blood vessels transport blood, oxygen, nutrients, wastes.

• Lymphatic system: Returns leaked fluid to blood, houses immune cells.

• Respiratory system: Supplies blood with oxygen, removes carbon dioxide.

• Digestive system: Breaks down food, absorbs nutrients, eliminates waste.

• Urinary system: Eliminates nitrogenous wastes, regulates water, electrolytes, acid-base balance.

• Reproductive system: Produces offspring, includes male and female reproductive organs.

Functions Necessary for Life

• Metabolism

• Excretion

• Digestion

• Reproduction

• Growth

• Movement

• Responsiveness

• Maintaining boundaries

Basic Needs of Humans

• Nutrients

• Oxygen

• Water

• Normal body temperature

• Appropriate atmospheric pressure

Homeostasis

Definition and Mechanisms

Homeostasis is the maintenance of a stable internal environment, essential for normal body function and survival. It depends on normal concentrations of water, nutrients, oxygen, and body temperature.

• Negative feedback: Works to correct a deviation from a set point (returns to normal). Most homeostatic mechanisms are negative feedback loops.

• Positive feedback: Enhances or exaggerates the original stimulus. Used in processes like blood clotting and childbirth.

Homeostatic mechanism involves:

• Stimulus: Produces change in variable.

• Receptor: Detects change.

• Input: Information sent along afferent pathway to control center.

• Control center: Determines set point, analyzes input, determines response.

• Output: Information sent along efferent pathway to effector.

• Effector: Carries out response to return variable to homeostasis.

Example: Regulation of body temperature (thermoregulation).

Basic Chemistry for Anatomy & Physiology

Atoms, Elements, and Matter

• Matter: Anything that has mass and takes up space.

• Element: Substance whose atoms all contain the same number of protons.

• Atom: Smallest unit of an element, composed of protons, neutrons, and electrons.

Major Elements in the Human Body

• Carbon – 18.5%

• Oxygen – 65%

• Hydrogen – 9.5%

• Nitrogen – 3.3%

Atomic Structure

• Protons: Positive charge

• Neutrons: Neutral

• Electrons: Negative charge

• Atomic number: Number of protons in an atom

• Atomic weight: Average mass of all isotopes of an atom

Examples:

• Carbon: Atomic number 6

• Oxygen: Atomic number 8

• Hydrogen: Atomic number 1

• Nitrogen: Atomic number 7

Isotopes and Ions

• Isotope: Atom of the same element with different numbers of neutrons; some are radioactive and used in medical diagnosis (e.g., radioactive iodine).

• Ion: Atom or molecule with a positive or negative charge.

• Cation: Positive charge

• Anion: Negative charge

Chemical Bonds

• Covalent bond: Sharing of electrons (e.g., O2, H2O)

• Ionic bond: Transfer of electrons (e.g., NaCl)

• Hydrogen bond: Weak attraction between a hydrogen atom and an electronegative atom (e.g., DNA, water)

Molecules and Compounds

• Molecule: Two or more atoms bonded together.

• Compound: Molecule containing atoms of different elements.

Water and Its Importance

• Water is a polar covalent molecule, making it an excellent solvent.

• Hydrogen bonding and polarity allow water to dissolve many substances.

Chemical Reactions

• Synthesis reactions: Build larger molecules (A + B → AB)

• Decomposition reactions: Break down molecules (AB → A + B)

• Exchange reactions: Bonds are both made and broken (AB + CD → AD + CB)

• Reversible reactions: Can proceed in both directions

Acids, Bases, and Salts

• Acids: Release H+ ions in solution

• Bases: Release OH- ions in solution

• Salts: Ionic compounds that dissociate in water

• Electrolytes: Substances that conduct electricity when dissolved in water

pH scale: Measures hydrogen ion concentration

• Blood pH: 7.35 – 7.45

• Acidosis: pH < 7.35

• Alkalosis: pH > 7.45

Organic and Inorganic Molecules

• Organic molecules: Contain carbon, usually large, covalently bonded (e.g., carbohydrates, lipids, proteins, nucleic acids)

• Inorganic molecules: Generally do not contain carbon (e.g., water, salts)

Major Classes of Organic Compounds

• Carbohydrates: Carbon, hydrogen, oxygen. Main source of energy.

• Proteins: Carbon, hydrogen, oxygen, nitrogen. Build and repair tissues.

• Lipids: Carbon, hydrogen, oxygen. Store energy, form cell membranes.

• Nucleic acids: Carbon, hydrogen, oxygen, nitrogen, phosphorus. Store genetic information.

Categories of Carbohydrates

• Monosaccharides: Simple sugars, important for cellular respiration.

• Disaccharides: Two monosaccharides joined together (e.g., lactose in milk).

• Polysaccharides: Long chains of monosaccharides (e.g., starch in plants, glycogen in animals).

Lipids

• Triglycerides: Fats and oils, energy storage.

• Phospholipids: Major component of cell membranes.

• Steroids: Cholesterol, hormones.

• Saturated fats: No double bonds, solid at room temperature.

• Unsaturated fats: One or more double bonds, liquid at room temperature.

Proteins

• Amino acids: Building blocks of proteins.

• Protein structure:

  • Primary: Sequence of amino acids.

  • Secondary: Alpha helices and beta sheets (hydrogen bonding).

  • Tertiary: 3D folding due to interactions among R groups.

  • Quaternary: Multiple polypeptide chains (e.g., hemoglobin).

• Denaturation: Loss of protein shape due to heat, pH, or chemicals.

Nucleic Acids

• Building blocks: Nucleotides

• Components of nucleotides:

  • Phosphate group

  • Sugar (ribose or deoxyribose)

  • Nitrogenous base

Summary Table: Major Organic Molecules

Additional info:

• Some explanations and examples were expanded for clarity and completeness.

• Tables were recreated to summarize key points on carbohydrates and organic molecules.

• All major points from the provided notes were included and organized by topic for exam preparation.