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Questions and Answers

What is the outermost layer of the skin called?

  • Dermis
  • Epidermis (correct)
  • Subcutaneous Layer
  • Hypodermis

    • The dermis layer is avascular and made of connective tissue.

    False

    What are the primary functions of the integumentary system?

    Regulate temperature, protect the body, sense signals, excrete and absorb chemicals, store blood and energy, synthesize vitamin D.

    The epidermis consists of ______ stratified squamous epithelium.

    <p>keratinized</p> Signup and view all the answers

    Match the cell types in the epidermis with their functions:

    <p>Keratinocytes = Produce keratin and waterproof sealant Melanocytes = Contain melanin to absorb UV light Langerhans cells = Phagocytize invaders through phagocytosis</p> Signup and view all the answers

    What is the primary function of hair?

    <p>It protects and insulates the body</p> Signup and view all the answers

    The cuticle of hair is the deepest layer of the hair structure.

    <p>False</p> Signup and view all the answers

    What composes the internal layer of the hair follicle?

    <p>hair matrix</p> Signup and view all the answers

    Hair protects the scalp from ____ radiation.

    <p>UV</p> Signup and view all the answers

    Which type of skin cancer is considered the most common?

    <p>Basal cell carcinoma</p> Signup and view all the answers

    Hair follicles are made up of muscle and nerve tissue.

    <p>False</p> Signup and view all the answers

    The ____ is responsible for minimizing heat loss by trapping air close to the skin.

    <p>hair</p> Signup and view all the answers

    Match the type of skin cancer with its corresponding information:

    <p>Basal cell carcinoma = Most common skin cancer, generally benign Squamous cell carcinoma = Represents 20% of skin cancers Malignant melanoma = Cancers of melanocytes Both basal and squamous = Involves uncontrolled epithelial cell proliferation</p> Signup and view all the answers

    What type of cells are primarily responsible for sensing touch in the skin?

    <p>Tactile epithelial cells</p> Signup and view all the answers

    The skin consists of five strata in most areas of the body.

    <p>False</p> Signup and view all the answers

    What layer of the epidermis is known for containing stem cells?

    <p>Stratum basale</p> Signup and view all the answers

    The stratum ________ is composed of dead, flat keratinocytes and is the most superficial layer of the skin.

    <p>corneum</p> Signup and view all the answers

    Match the skin strata with their main characteristics:

    <p>Stratum basale = Deepest layer with stem cells Stratum spinosum = Provides strength to skin Stratum granulosum = Contains dying cells Stratum corneum = Most superficial layer with dead cells</p> Signup and view all the answers

    What process do cells in the stratum granulosum undergo?

    <p>Apoptosis</p> Signup and view all the answers

    The dermis consists of two regions: papillary and reticular.

    <p>True</p> Signup and view all the answers

    Name the type of connective tissue that makes up the reticular region of the dermis.

    <p>Dense irregular connective tissue</p> Signup and view all the answers

    Differences in human skin color are mainly due to varying amounts of ________ produced by melanocytes.

    <p>melanin</p> Signup and view all the answers

    How long does it take for new cells at the stratum basale to emerge at the stratum corneum?

    <p>4-6 weeks</p> Signup and view all the answers

    Fingerprints are formed by the epidermal ridges that reflect the underlying dermal papillae.

    <p>True</p> Signup and view all the answers

    What enzyme is involved in melanin synthesis and increases with UV exposure?

    <p>Tyrosinase</p> Signup and view all the answers

    Tattoos penetrate into the ________ layer of the skin.

    <p>dermis</p> Signup and view all the answers

    Which stratum appears clear and is found only in thick skin?

    <p>Stratum lucidum</p> Signup and view all the answers

    Which of the following is NOT a characteristic of living things?

    <p>Absorb nutrients</p> Signup and view all the answers

    The study of function in living organisms is known as anatomy.

    <p>False</p> Signup and view all the answers

    What term describes the interrelatedness of structure and function in the human body?

    <p>Anatomy and physiology are interdependent.</p> Signup and view all the answers

    An organ system comprises a group of related organs with ______ functions.

    <p>independent</p> Signup and view all the answers

    Which organ system is primarily responsible for transporting blood throughout the body?

    <p>Cardiovascular system</p> Signup and view all the answers

    Match the following organ systems with their primary functions:

    <p>Integumentary system = Covers and protects the body Muscular system = Moves and heats the body Respiratory system = Exchanges gases between the body and the environment Digestive system = Acquires and extracts nutrients</p> Signup and view all the answers

    What are the six levels of structural organization in the human body?

    <p>Chemical level, cellular level, tissue level, organ level, system level, organ-animal level.</p> Signup and view all the answers

    The lymphatic system is essential for the acquisition of nutrients.

    <p>False</p> Signup and view all the answers

    What is the primary function of the urinary system?

    <p>Removes wastes and maintains pH of the body</p> Signup and view all the answers

    Positive feedback loops move the body towards homeostasis.

    <p>False</p> Signup and view all the answers

    What term describes the fluid found between tissue cells?

    <p>interstitial fluid</p> Signup and view all the answers

    Homeostasis is the _____ upkeep of a set of internal conditions.

    <p>dynamic</p> Signup and view all the answers

    Match the following terms with their definitions:

    <p>Medial = Nearer to the middle of the body Proximal = Closer to the place of attachment Superior = Closer to the head of the body Distal = Further away from the place of attachment</p> Signup and view all the answers

    Which structure acts as a control center in a feedback loop?

    <p>Brain</p> Signup and view all the answers

    Chronic homeostatic imbalances can lead to disorders and diseases.

    <p>True</p> Signup and view all the answers

    What is the term for the imaginary line that divides the body into right and left sides?

    <p>midline</p> Signup and view all the answers

    The main organ of the reproductive system in females is the _____

    <p>uterus</p> Signup and view all the answers

    Which feedback mechanism is most common in the human body for maintaining homeostasis?

    <p>Negative feedback</p> Signup and view all the answers

    What separates the thoracic cavity from the abdominopelvic cavity?

    <p>Diaphragm</p> Signup and view all the answers

    The pericardial cavity encases the lungs.

    <p>False</p> Signup and view all the answers

    Name the two types of peritoneum and their corresponding locations.

    <p>Visceral peritoneum lines the viscera; Parietal peritoneum lines the abdominal cavity wall.</p> Signup and view all the answers

    The _____ cavity contains organs of the digestive system.

    <p>abdominal</p> Signup and view all the answers

    Match the following body cavities with their contents:

    <p>Cranial cavity = Brain Thoracic cavity = Lungs Abdominopelvic cavity = Digestive organs Vertebral canal = Spinal cord</p> Signup and view all the answers

    Which of the following regions is NOT a part of the abdominopelvic cavity?

    <p>Thoracic region</p> Signup and view all the answers

    Ventral body cavities are primarily surrounded by serous membranes.

    <p>True</p> Signup and view all the answers

    Identify one organ found in the retroperitoneal space.

    <p>Kidneys</p> Signup and view all the answers

    The _____ divides the abdominopelvic cavity into regions and is represented by midclavicular lines.

    <p>subcostal line</p> Signup and view all the answers

    Which of the following structures is part of the mediastinum?

    <p>Heart</p> Signup and view all the answers

    Which characteristic is NOT a definition of living things?

    <p>Possess lifeless structures</p> Signup and view all the answers

    Anatomy refers to the study of functions in living organisms.

    <p>False</p> Signup and view all the answers

    What is the primary function of the muscular system?

    <p>Moves and heats the body.</p> Signup and view all the answers

    An organ system is a group of related organs with __________ functions.

    <p>independent</p> Signup and view all the answers

    Match the following organ systems with their primary functions:

    <p>Integumentary system = Covers and protects the body. Nervous system = Senses signals and coordinates electrical responses. Cardiovascular system = Transports blood, nutrients, and gases throughout the body. Respiratory system = Exchanges gases between the body and the environment.</p> Signup and view all the answers

    Which organ system is responsible for defending the body from invaders?

    <p>Lymphatic/immune system</p> Signup and view all the answers

    The relationship between structure and function indicates that structures can perform any function regardless of their design.

    <p>False</p> Signup and view all the answers

    List the six levels of structural organization in the human body.

    <p>Chemical level, cellular level, tissue level, organ level, system level, organism level.</p> Signup and view all the answers

    Which of the following statements about enzymes is true?

    <p>Enzymes lower the activation energy required for reactions.</p> Signup and view all the answers

    Cofactors are only inorganic molecules that assist enzyme activity.

    <p>False</p> Signup and view all the answers

    What is the process called in which DNA is copied to form a new double helix?

    <p>replication</p> Signup and view all the answers

    The nitrogenous _____ in RNA include A, G, C, and U.

    <p>bases</p> Signup and view all the answers

    Match the following types of RNA with their functions:

    <p>mRNA = Encodes messages from genes to ribosomes rRNA = Catalyzes chemical reactions in ribosomes tRNA = Brings amino acids to ribosomes during translation</p> Signup and view all the answers

    Which component of ATP releases a large amount of energy when hydrolyzed?

    <p>Phosphate group</p> Signup and view all the answers

    Enzymes have an infinite lifespan and do not require any regulation.

    <p>False</p> Signup and view all the answers

    What is the function of proenzymes in enzyme Activity?

    <p>Proenzymes are inactive forms that must be processed to become active.</p> Signup and view all the answers

    In DNA, the pentose sugar is called _____ while in RNA it is called ribose.

    <p>deoxyribose</p> Signup and view all the answers

    Which type of bond is broken when activation energy is lowered by enzymes?

    <p>Any of the above depending on the substrate</p> Signup and view all the answers

    What type of linkage joins monosaccharides to form disaccharides?

    <p>Glycosidic linkage</p> Signup and view all the answers

    Polysaccharides are made up of at least 100-1000 monosaccharides.

    <p>True</p> Signup and view all the answers

    What are the four classes of biological monomers?

    <p>Carbohydrates, Lipids, Proteins, Nucleic acids</p> Signup and view all the answers

    The storage polysaccharide found in animals is ________.

    <p>glycogen</p> Signup and view all the answers

    Match the following classes of lipids with their descriptions:

    <p>Fatty acids = Building blocks of fats Triglycerides = Fats and oils Phospholipids = Main component of cell membranes Steroids = Four fused carbon rings</p> Signup and view all the answers

    Which type of bond forms when amino acids combine to create proteins?

    <p>Peptide bond</p> Signup and view all the answers

    All lipids have a monomeric unit similar to carbohydrates.

    <p>False</p> Signup and view all the answers

    What is the main function of cholesterol within biological membranes?

    <p>Fluidity buffer</p> Signup and view all the answers

    The ________ group makes sterols slightly amphipathic.

    <p>hydroxyl</p> Signup and view all the answers

    Match the following types of carbohydrates with their characteristics:

    <p>Monosaccharides = Simple sugars Disaccharides = Two monosaccharides linked Polysaccharides = Many monosaccharides linked</p> Signup and view all the answers

    Which of the following is a property of saturated fatty acids?

    <p>Only contain single covalent C-C bonds</p> Signup and view all the answers

    Fibrous proteins are typically water-soluble.

    <p>False</p> Signup and view all the answers

    What is the primary structure of proteins?

    <p>Amino acid sequence</p> Signup and view all the answers

    Lipids are primarily ________ molecules.

    <p>hydrophobic</p> Signup and view all the answers

    Which molecule serves as the starting point for the synthesis of steroids in the body?

    <p>Cholesterol</p> Signup and view all the answers

    What is the function of the diaphragm in relation to the body cavities?

    <p>It separates the thoracic and abdominopelvic cavities.</p> Signup and view all the answers

    The pleura surrounds the kidneys in the peritoneal cavity.

    <p>False</p> Signup and view all the answers

    Name the two types of peritoneum and their locations.

    <p>Visceral peritoneum lines the viscera, and parietal peritoneum lines the abdominal cavity wall.</p> Signup and view all the answers

    The ___ cavity contains the urinary bladder and reproductive organs.

    <p>pelvic</p> Signup and view all the answers

    Match the following organs to their respective cavities:

    <p>Heart = Pericardial cavity Lungs = Pleural cavity Abdominal organs = Abdominal cavity Pelvic organs = Pelvic cavity</p> Signup and view all the answers

    Which of the following statements is true about water?

    <p>Ice floats because it expands upon freezing.</p> Signup and view all the answers

    Hydrogen bonds significantly contribute to the properties of water.

    <p>True</p> Signup and view all the answers

    What is homeostasis?

    <p>Homeostasis is the maintenance of stable internal conditions within a particular range.</p> Signup and view all the answers

    The regions of the abdominopelvic cavity are divided by the ___ lines and ___ lines.

    <p>midclavicular, transtubercular</p> Signup and view all the answers

    Match the body cavities with their functions:

    <p>Dorsal cavity = Contains the brain and spinal cord Ventral cavity = Contains thoracic and abdominopelvic organs Pleural cavity = Surrounds the lungs Pericardial cavity = Surrounds the heart</p> Signup and view all the answers

    What describes a hydrophilic substance?

    <p>A substance that easily dissolves in water</p> Signup and view all the answers

    The abdominal cavity includes both the thoracic and pelvic organs.

    <p>False</p> Signup and view all the answers

    List three examples of viscera found in the abdominal cavity.

    <p>Stomach, liver, small intestine</p> Signup and view all the answers

    The ___ regions of the abdominopelvic cavity are located beneath the ribs.

    <p>hypochondriac</p> Signup and view all the answers

    Match the following terms with their definitions:

    <p>Visceral peritoneum = Lines the organs in the abdominal cavity Parietal peritoneum = Lines the abdominal cavity wall Serous fluid = Lubricates the viscera Hydrophobic = Water-repelling substances</p> Signup and view all the answers

    What is the primary function of the urinary system?

    <p>Removes wastes and maintains pH of the body</p> Signup and view all the answers

    Negative feedback loops enhance the initial change in homeostasis.

    <p>False</p> Signup and view all the answers

    What term describes the liquid found between tissue cells?

    <p>interstitial fluid</p> Signup and view all the answers

    Homeostasis is the __________ upkeep of a set of internal conditions.

    <p>dynamic</p> Signup and view all the answers

    Match the following systems with their primary functions:

    <p>Urinary system = Removes waste from the body Reproductive system = Produces gametes and nurtures young Lymphatic system = Maintains fluid balance and immune response Endocrine system = Regulates bodily functions through hormones</p> Signup and view all the answers

    What happens when the body fails to maintain homeostasis for a prolonged period?

    <p>Leads to disorders, diseases, or death</p> Signup and view all the answers

    The negative feedback loop is a rare way the body responds to changes.

    <p>False</p> Signup and view all the answers

    Identify the receptors involved in detecting blood pressure changes.

    <p>baroreceptors</p> Signup and view all the answers

    The __________ region of the body refers to the neck.

    <p>cervical</p> Signup and view all the answers

    Match the anatomical positions with their descriptions:

    <p>Supine = Facing up Prone = Facing down Proximal = Closer to point of attachment Distal = Further from point of attachment</p> Signup and view all the answers

    Which type of cells possess membranous organelles?

    <p>Eukaryotic cells</p> Signup and view all the answers

    The cytoplasm includes the jelly-like fluid surrounding the nucleus only.

    <p>False</p> Signup and view all the answers

    What is the main function of microtubules in a cell?

    <p>To segregate chromosomes during cell division and form cilia and flagella.</p> Signup and view all the answers

    The ________ is the flexible barrier that separates the external environment from the internal environment of the cell.

    <p>plasma membrane</p> Signup and view all the answers

    Match the following organelles with their primary functions:

    <p>Mitochondrion = Energy production Ribosome = Protein synthesis Nucleus = Genetic information storage Centrosome = Microtubule organization</p> Signup and view all the answers

    What is the primary function of aquaporins?

    <p>Facilitate the movement of water</p> Signup and view all the answers

    In a hypotonic solution, a red blood cell will shrink.

    <p>False</p> Signup and view all the answers

    What type of solution is typically administered intravenously to maintain osmotic balance?

    <p>Isotonic solution</p> Signup and view all the answers

    A ______ solution has a lower solute concentration compared to the inside of a cell, causing water to move into the cell.

    <p>hypotonic</p> Signup and view all the answers

    Which of the following statements is true regarding osmolarity?

    <p>Osmolarity determines tonicity, affecting water movement.</p> Signup and view all the answers

    If a person is severely dehydrated, what type of solution should they drink to effectively rehydrate?

    <p>Hypotonic solution</p> Signup and view all the answers

    What happens to a cell in a hypertonic solution?

    <p>The cell shrinks.</p> Signup and view all the answers

    Match the following types of solutions with their effects on cells:

    <p>Hypotonic = Water moves into the cell Hypertonic = Water moves out of the cell Isotonic = No net water movement Dehydrated = Water deficit in cells</p> Signup and view all the answers

    What is the primary function of mitochondria?

    <p>Energy production</p> Signup and view all the answers

    Aerobic cellular respiration occurs only in the cytoplasm.

    <p>False</p> Signup and view all the answers

    What is the name of the structures formed by the folding of the inner mitochondrial membrane?

    <p>cristae</p> Signup and view all the answers

    The end products of aerobic cellular respiration are CO2 and H2O.

    <p>CO2 and H2O</p> Signup and view all the answers

    Match the terms with their definitions.

    <p>Mitosis = Division of the nucleus and its contents Cytokinesis = Division of the cytoplasmic components Telomeres = Protect chromosome ends from shortening Crossing Over = Exchange of genetic information between homologous chromosomes</p> Signup and view all the answers

    Which phase of the cell cycle involves DNA replication?

    <p>S phase</p> Signup and view all the answers

    Meiosis results in identical daughter cells.

    <p>False</p> Signup and view all the answers

    What is the term for the division of the cytoplasm during cell division?

    <p>cytokinesis</p> Signup and view all the answers

    The _____ mitochondria _____ are inherited from the mother.

    <p>mitochondria</p> Signup and view all the answers

    What is a primary function of telomeres?

    <p>Prevent chromosome shortening</p> Signup and view all the answers

    Sperm contribute their mitochondria to the egg during fertilization.

    <p>False</p> Signup and view all the answers

    What structure forms during prophase as chromatin condenses?

    <p>chromosomes</p> Signup and view all the answers

    At the end of meiosis II, there are four _____ gametes _____ with a haploid set of chromosomes.

    <p>gametes</p> Signup and view all the answers

    Match the following phases of mitosis with their descriptions:

    <p>Prophase = Nuclear envelope dissolution Metaphase = Chromosomes align at the equatorial plate Anaphase = Chromatids pulled to opposite poles Telophase = Formation of two new nuclei</p> Signup and view all the answers

    In which phase does the DNA polymerase operate during S phase?

    <p>DNA replication phase</p> Signup and view all the answers

    What is the main function of the sodium-potassium (Na+-K+) pump in animal cells?

    <p>Maintains higher Na+ outside the cell and higher K+ inside the cell</p> Signup and view all the answers

    Cyanide inhibits all forms of active transport.

    <p>True</p> Signup and view all the answers

    What is the primary role of the centrosome in animal cells?

    <p>Organizes microtubules</p> Signup and view all the answers

    Cilia and flagella are both composed of microtubules.

    <p>True</p> Signup and view all the answers

    What is the process called when substances are engulfed by phagocytic cells?

    <p>Phagocytosis</p> Signup and view all the answers

    Water moves from low solute concentration to high solute concentration through the process of __________.

    <p>osmosis</p> Signup and view all the answers

    What are the two types of endoplasmic reticulum?

    <p>Rough endoplasmic reticulum and smooth endoplasmic reticulum</p> Signup and view all the answers

    The dense region in the nucleus responsible for making ribosomal subunits is called the __________.

    <p>nucleolus</p> Signup and view all the answers

    Match the transport processes with their descriptions:

    <p>Endocytosis = Movement of substances into a cell via vesicles Exocytosis = Movement of substances out of a cell via vesicles Transcytosis = Movement through cells by endocytosis followed by exocytosis Secondary active transport = Moves two solutes simultaneously, one down and one up its gradient</p> Signup and view all the answers

    Which of the following statements is true about secondary active transport?

    <p>It harnesses energy from the primary active transport process.</p> Signup and view all the answers

    Match the following organelles with their functions:

    <p>Lysosomes = Break down cellular molecules Ribosomes = Translate mRNA into proteins Golgi complex = Modify and sort proteins Peroxisomes = Detoxify harmful substances</p> Signup and view all the answers

    Which ions are primarily stored in the smooth endoplasmic reticulum?

    <p>Calcium ions</p> Signup and view all the answers

    Symporters move two solutes in different directions across the membrane.

    <p>False</p> Signup and view all the answers

    Proteins are folded and packaged in the Golgi complex.

    <p>True</p> Signup and view all the answers

    What is the main energy molecule used in active transport?

    <p>ATP</p> Signup and view all the answers

    _________ are membrane sacs that transport products between certain organelles.

    <p>Vesicles</p> Signup and view all the answers

    What is the function of ribosomes in a cell?

    <p>Translate mRNA into proteins</p> Signup and view all the answers

    The __________ is all of the DNA in an organism.

    <p>genome</p> Signup and view all the answers

    Which of the following best describes osmosis?

    <p>Passive transport of water across the membrane</p> Signup and view all the answers

    Match the following terms with their definitions:

    <p>Codon = A triplet of nucleotides on mRNA Translation = The process of synthesizing proteins from mRNA Transcription = The synthesis of mRNA from DNA Ribosome = Structure that synthesizes proteins</p> Signup and view all the answers

    What type of proteins does the rough endoplasmic reticulum primarily synthesize?

    <p>Membrane-bound proteins</p> Signup and view all the answers

    MRNA is synthesized in the cytoplasm.

    <p>False</p> Signup and view all the answers

    What cellular structure is involved in the detoxification of alcohols?

    <p>Peroxisomes</p> Signup and view all the answers

    The __________ contains >60 different kinds of enzymes for breaking down cellular molecules.

    <p>lysosomes</p> Signup and view all the answers

    What is Tay-Sachs disease a result of?

    <p>Mutations in lysosomal enzymes</p> Signup and view all the answers

    What percentage of the membrane is composed of cholesterol?

    <p>20%</p> Signup and view all the answers

    Membrane fluidity is essential for biological function.

    <p>True</p> Signup and view all the answers

    Define membrane fluidity.

    <p>The ability for the lipid bilayer to move proteins and lipids laterally within the layer.</p> Signup and view all the answers

    The _______ of fatty acid tails affects the fluidity of the membrane.

    <p>saturation</p> Signup and view all the answers

    Match the following types of membrane proteins with their functions:

    <p>Integral proteins = Span the entire membrane Peripheral proteins = Bound by electrostatic interactions Receptors = Bind specific molecules and send signals Enzymes = Catalyze chemical reactions</p> Signup and view all the answers

    What type of substances can generally diffuse through the membrane without assistance?

    <p>Nonpolar molecules</p> Signup and view all the answers

    Cholesterol makes the membrane less fluid.

    <p>False</p> Signup and view all the answers

    What happens to the fluidity of the membrane when the temperature increases?

    <p>The fluidity of the membrane increases.</p> Signup and view all the answers

    Facilitated diffusion involves the use of _______ proteins to help transport substances.

    <p>transport</p> Signup and view all the answers

    Which of the following describes the shape of saturated fatty acids?

    <p>Straight</p> Signup and view all the answers

    Higher concentration gradients increase the rate of diffusion.

    <p>True</p> Signup and view all the answers

    What is the primary role of glycoproteins in the cell membrane?

    <p>Cell identity markers help distinguish different cell types.</p> Signup and view all the answers

    The process by which solutes move from high to low concentration without energy is called _______.

    <p>diffusion</p> Signup and view all the answers

    Ion channels are used for what type of transport?

    <p>Facilitated diffusion</p> Signup and view all the answers

    Match the following terms with their definitions:

    <p>Entropy = Tendency of solutes to spread out Concentration gradient = Difference in concentration Fluid mosaic model = Description of membrane structure Passive transport = Movement without energy</p> Signup and view all the answers

    Study Notes

    The Integumentary System

    • The integumentary system is composed of skin, hair, nails, oil and sweat glands, and sensory receptors.
    • Skin is the largest organ, comprising 7% of body weight.
    • Skin thickness varies from 0.5 mm on eyelids to 4 mm on heels.
    • The epidermis, the outermost layer of skin, is avascular.
    • The dermis lies beneath the epidermis, composed of vascularized connective tissue.
    • The subcutaneous layer, or hypodermis, anchors skin structures to underlying fascia and contains pressure receptors.

    Functions of the Integumentary System

    • Regulates body temperature.
    • Protects the body from external insults.
    • Senses signals.
    • Excretes and absorbs chemicals.
    • Stores blood and energy.
    • Synthesizes vitamin D.

    The Epidermis

    • Consists of keratinized stratified squamous epithelium.
    • Contains various cell types:
      • Keratinocytes: Layered cells that produce keratin and waterproof sealant.
      • Melanocytes: Contain melanin granules, a pigment that absorbs UV light and protects DNA.
      • Intraepidermal macrophages (Langerhans cells): UV-sensitive phagocytes that engulf and destroy invaders.
      • Tactile epithelial cells: Sense touch and are in direct contact with tactile discs (nervous tissue).

    Strata of the Epidermis

    • The epidermis is subdivided into strata, layers of keratinocytes at different maturity levels.
    • Most of the body is covered by skin with four strata.
    • Palms and soles have five strata due to high abrasion.
    • The strata, from deepest to most superficial, are:
      • Stratum basale: Contains stem cells that replenish overlying strata, rich in keratin intermediate filaments for strength.
      • Stratum spinosum: Provides strength to skin with thicker, tougher keratin intermediate filaments.
      • Stratum granulosum: Contains dying cells undergoing apoptosis, producing keratohyalin and lamellar granules for sealing and waterproofing.
      • Stratum corneum: Most superficial layer, composed of dead, flat cells that slough off with abrasion.
      • Stratum lucidum: Found only in thick skin, between the stratum granulosum and stratum corneum, composed of dead, flat keratinocytes.

    Growth of the Epidermis

    • Takes 4-6 weeks for new cells at the stratum basale to reach the stratum corneum.
    • Keratinization reinforces skin through keratin accumulation in dying cells.
    • Cells further from the stratum basale have reduced access to nutrients.

    The Dermis

    • Composed of connective tissue with great tensile strength.
    • Divided into two regions:
      • Papillary region: Made of areolar connective tissue with collagen and elastic fibers, contains dermal papillae (tissue extensions) that house capillaries and touch/pain sensing nerves.
      • Reticular region: Made of dense irregular connective tissue, a mesh-like network of collagen fibers providing resistance to stretching and shear forces.

    Fingerprints

    • Unique and differ even between identical twins.
    • Formed by epidermal ridges, influenced by the shape of dermal papillae.
    • Increase friction for grip and touch sensitivity.
    • Sweat pores open on the surface.

    Skin Color

    • Differences in skin color arise from varying melanin production, not melanocyte number.
    • Melanin accumulation can result in freckles, age spots, or moles (nevuses).
    • A tan is caused by increased tyrosinase activity in melanocytes upon UV exposure.
    • Tan fading reflects the replacement of pigmented cells with less melanin-producing cells.

    Accessory Structures of Skin: Hair, Glands, and Nails

    Hair

    • Protects and insulates the body, aiding in sensing stimuli.
    • Found on the scalp, eyebrows, eyelashes, nasal cavity, armpits, and external genitalia.
    • Protects the scalp from UV radiation, the eyes and nasal cavity from invasion.
    • Traps air near the skin to minimize heat loss.
    • Touch receptors connected to hair movement sense stimuli.

    Anatomy of Hair

    • Hair consists of:
      • Root: Embedded in the dermis or subcutaneous layer.
      • Shaft: Superficial portion of the hair.
    • Root and shaft comprise three layers:
      • Medulla: Deepest layer, contains pigmented cells.
      • Cortex: Middle layer, makes up the bulk of hair.
      • Cuticle: Most superficial layer, composed of flat, keratinized epithelial cells arranged like roof shingles.

    Hair Follicle

    • Surrounds the hair root.
    • Has an external layer of epithelial tissue and an internal layer that forms the hair matrix, which divides continuously for hair growth.

    Hair and Associated Structures

    • Hair is connected to arrector pili, smooth muscle that pulls hair when cold or fearful.
    • Hair loss can be triggered by various factors, including genetics and medical conditions.

    Nails

    • Protect fingertips and toes.
    • Composed of keratinized epithelial cells.
    • Nail body: Visible portion of the nail.
    • Nail root: Embedded portion of the nail in a fold of skin.
    • Nail matrix: Produces new nail cells.
    • Lunula: Crescent-shaped white area at the base of the nail.
    • Nail bed: Underlying skin that nourishes the nail.
    • Eponychium (cuticle): Skin fold at the base of the nail.
    • Hyponychium: Skin under the free edge of the nail.

    Sweat and Oil Glands

    Sweat Glands

    • Eccrine sweat glands: Found throughout the skin, produce watery sweat for thermoregulation.
    • Apocrine sweat glands: Found in axillary and genital areas, produce thicker, milky sweat, influenced by hormones.

    Oil Glands (Sebaceous Glands)

    • Secrete sebum, an oily substance that lubricates and waterproofs the skin and hair.

    Wound Healing and Burns

    Wound Healing

    • Process of repairing damaged tissue.
    • Involves inflammation, proliferation, and remodeling phases.
    • Inflammation: Blood clots form, immune cells arrive, and tissue debris is cleared.
    • Proliferation: New cells and blood vessels grow.
    • Remodeling: Scar tissue forms, and tissue strength is restored.

    Burns

    • Classified by depth of tissue damage:
      • First-degree: Superficial, only affects the epidermis.
      • Second-degree: Affects the epidermis and part of the dermis.
      • Third-degree: Destroys the epidermis and dermis, may involve subcutaneous tissue.
      • Fourth-degree: Extends beyond subcutaneous tissue to muscle, tendons, and bone.

    Skin Cancer

    • Types of skin cancer:
      • Basal cell carcinoma: Most common, arising from the stratum basale, generally benign.
      • Squamous cell carcinoma: Originates from the stratum spinosum, can be malignant.
      • Malignant melanoma: Arises from melanocytes, most dangerous form of skin cancer.

    Summary

    • The integumentary system protects from abrasion, dehydration, radiation, and invasion.
    • Skin color is determined by melanin production, with melanin accumulation leading to various pigmentation patterns.
    • Wound healing is crucial for maintaining integumentary homeostasis, with burns presenting a severe challenge.
    • Excessive UV exposure increases the risk of skin cancer, with different types arising from specific skin cell origins.

    Characteristics of Living Things

    • Living things metabolize, respond to stimuli, move, grow, and develop, and reproduce.

    Matter

    • Living things and their environment are composed of matter.

    Anatomy

    • Anatomy is the study of the structures of the body and their relationships with one another.

    Physiology

    • Physiology is the study of the function of the body.

    Levels of Structural Organization

    • The human body is organized into six levels: chemical, cellular, tissue, organ, system, and organismal.

    Relationship between Anatomy and Physiology

    • Structures are specialized for particular functions.
    • Functions are limited or enhanced by structure.

    Organ Systems

    • An organ system is a group of organs that work together to perform a coordinated function.
    • There are 11 organ systems in the human body.

    Major Organs and Functions of Each System:

    • Integumentary system - skin, nails, hair - covers and protects the body.
    • Skeletal system - bones, joints, cartilage - protects and supports the body.
    • Muscular system - skeletal muscles - moves and heats the body.
    • Nervous system - brain, spinal cord, nerves, and sensory organs - senses signals and coordinates electrical responses.
    • Endocrine system - cells and glands that secrete hormones - senses signals and coordinates chemical responses.
    • Cardiovascular system - heart, blood, and blood vessels - transports blood, nutrients, and gases throughout the body.
    • Lymphatic/immune system lymph node, thoracic duct, red bone marrow, lymphatic vessel, spleen, thymus, and tonsils - defends the body from invaders.
    • Respiratory system - pharynx, larynx, trachea, bronchial tubes, lungs, diaphragm - exchanges gases between the body and the environment. Also eliminates carbon dioxide waste.
    • Digestive system - liver, oral cavity, pharynx, esophagus, stomach, small and large intestines - acquires and extracts nutrients and eliminates wastes.
    • Urinary system - urinary bladder, urethra, kidney, and ureter - removes wastes and maintains pH of the body. Disposes of nitrogenous wastes.
    • Reproductive system - gonads, testes, ovary, vagina, prostate, penis, uterus - produces gametes, enables copulation, and, in females, houses and nourishes young.

    Body Fluids

    • Body systems are connected via body fluids.
    • Extracellular fluid is fluid outside of cells.
    • Interstitial fluid is the fluid between tissues.
    • Blood plasma is the fluid component of blood within blood vessels and organs of the cardiovascular system.
    • Lymph is fluid inside lymphatic vessels.

    Homeostasis

    • Homeostasis is the dynamic upkeep of a set of internal conditions within set parameters to maintain a stable internal environment.
    • Receptor detects the change.
    • Control center coordinates a response.
    • Effector carries out the response according to the control center.

    Negative Feedback Loops

    • Negative feedback loops reverse changes to maintain homeostasis.
    • Example: Blood pressure regulation - baroreceptors detect an increase in blood pressure, sending the signal to the brain, which sends nerve impulses to the heart to decrease blood flow and dilates blood vessels to decrease pressure. This lowers blood pressure back to normal.
    • This is the most common way the human body responds to change.

    Positive Feedback Loops

    • Positive feedback loops enhance the initial change.
    • Example: Childbirth - Nerve receptors in the cervix sense dilation, sending a signal to the brain, which releases oxytocin into the blood. Oxytocin causes the myometrium of the uterus to contract, which further stretches the cervix.
    • This is a rare way the human body responds to changes.

    Consequences of Homeostatic Imbalance

    • Prolonged or chronic homeostatic imbalances can lead to disorders, diseases, and/or death.
    • Disorders result from abnormal body function.
    • Diseases are disorders with characteristic signs and symptoms linked to a specific cause.
    • Symptoms are changes in body function that can be felt or reported (subjective).
    • Signs are changes in body functions that can be measured and observed (objective).

    Anatomical Directional Terms

    • Directional terms describe the relative location of structures in the body.

    Anatomical Position

    • Used as a reference point for describing body structures.
    • The body is upright, facing forward, with arms at the sides, palms facing forward.

    Midline

    • An imaginary line that divides the body into right and left sides.
    • The location of structures is described in relation to this midline.

    Directional Term Definitions:

    • Medial: nearer to the midline of the body.
    • Lateral: further away from the middle of the body.
    • Proximal: closer to the point of attachment.
    • Distal: further away from the point of attachment.
    • Superior: closer to the head of the body.
    • Inferior: closer to the feet.

    Body Planes and Sections

    • A plane is an imaginary flat surface that divides the body.
    • Sections are cuts along a plane.
    • It is important to understand the plane of a section to interpret images or scans of the body.

    Body Cavities

    • Body cavities protect, hold, and support internal structures.

    Dorsal Body Cavity

    • Includes the cranial and vertebral canal.
    • Cranial cavity: formed by cranial bones and contains the brain.
    • Vertebral canal: formed by vertebrae and contains the spinal cord.

    Ventral Body Cavity

    • Includes the thoracic and abdominopelvic cavities.
    • Divided by the diaphragm.
    • Organs within ventral cavities are called viscera.
    • Viscera are surrounded by serous membranes.

    Serous Membranes

    • Thin, slippery membranes that do not open to the exterior of the body.
    • Pleura encases the lungs in the pleural cavity.
    • Pericardium encases the heart in the pericardial cavity.
    • Peritoneum encases the abdominal cavity and its organs.

    Thoracic Cavity

    • Formed by ribs, intercostal muscles, sternum, and thoracic vertebrae.
    • Pericardial cavity: fluid-filled space around the heart.
    • Pleural cavities: fluid-filled spaces around each of the lungs.
    • Mediastinum: space between the lungs. Contains all organs in the thoracic cavity except the lungs.

    Abdominopelvic Cavity

    • Two cavities that together extend from the diaphragm to the groin.
    • Abdominal cavity: contains organs of the digestive system + accessory glands.
    • Pelvic cavity: contains the urinary bladder + the organs and glands of the reproductive system.
    • The large intestine extends through both cavities.

    Peritoneal Viscera

    • Structures within the peritoneum.
    • Includes the stomach, spleen, liver, gallbladder, small intestine, and most of the large intestine.

    Retroperitoneal Viscera

    • Structures outside of the peritoneum.
    • Includes the kidneys, adrenal glands, pancreas, duodenum, ascending and descending colon, parts of the abdominal aorta, and inferior vena cava.

    Abdominopelvic Cavity Regions

    • Midclavicular lines divide the abdominopelvic cavity into three columns.
    • Subcostal and transtubercular lines divide the cavity into three rows.

    Abdominpelvic Cavity Regions

    • Right and left hypochondriac regions
    • Right and left lumbar regions
    • Right and left inguinal regions
    • Epigastric region
    • Umbilical region
    • Hypogastric region

    Abdominopelvic Cavity Quadrants

    • Midsagittal and transverse lines drawn at the umbilicus divide the cavity into four sections:
    • Right upper quadrant
    • Right lower quadrant
    • Left upper quadrant
    • Left lower quadrant

    Summary

    • Anatomy is the study of structure; physiology is the study of function.
    • The body is organized into ascending levels of complexity, from atoms to an organism.
    • There are 11 organ systems, each with a specialized function. However, the organ systems cooperate and are interdependent.
    • The volume and composition of body fluids must be maintained at all times.
    • Homeostasis is the constant maintenance of conditions within a particular range, mostly maintained through negative feedback loops.
    • Human anatomy can be described in positional, directional, and regional terms.

    Characteristics of Living Things

    • Living things are made of matter, including complex chemical substances.
    • Living things respond to stimuli, grow and develop, reproduce, and move.

    Anatomy and Physiology

    • Anatomy studies the structure of living things and their relationships.
    • Physiology studies the function of living things.
    • Structure and function are closely related; structures are designed for specific functions.

    Levels of Structural Organization

    • The human body is organized into six levels: chemical, cellular, tissue, organ, system, and organism.
    • The organ level is a group of tissues working together to perform a coordinated function.

    Organ Systems

    • The eleven organ systems are: integumentary, skeletal, muscular, nervous, endocrine, cardiovascular, lymphatic, respiratory, digestive, urinary, and reproductive systems.
    • Each system has a specialized function, but they cooperate and are interdependent.

    Body Fluids

    • Extracellular fluid is the fluid outside of cells.
    • Interstitial fluid is the fluid between tissue cells.
    • Blood plasma is the fluid component of blood.
    • Lymph is the fluid inside lymphatic vessels.
    • Maintaining fluid volume and composition is essential for survival.

    Homeostasis

    • Homeostasis is the dynamic maintenance of internal conditions within a particular range.
    • It depends on receptors detecting change, a control center coordinating a response, and effectors carrying out the response.
    • Negative feedback loops reverse changes to maintain homeostasis (most common).
    • Positive feedback loops enhance the initial change (less common).
    • Homeostatic imbalances can lead to disorders, diseases, or death.

    Anatomical, Directional, and Positional Terms

    • The anatomical position is a standard reference point for describing the body.
    • Directional terms describe the location of structures relative to one another.
    • Planes divide the body into sections for imaging.

    Body Cavities

    • Body cavities protect, hold, and support internal organs.
    • The dorsal cavities include the cranial cavity and the vertebral canal.
    • The ventral cavities include the thoracic and abdominopelvic cavities, separated by the diaphragm.
    • Serous membranes line the cavities and organs, producing serous fluid for lubrication.
    • Regions of abdominopelvic cavity are important in medicine to diagnose and treat illness.
    • Quadrants are used for quick assessments, while regions provide detailed anatomical descriptions.

    Water Properties

    • Water exhibits cohesion, moderation of temperature, expansion upon freezing, and acts as a solvent.
    • These properties are essential for life.

    Biological Molecules

    • All living things are made of matter; molecules in living things are subject to the same chemical and physical laws.
    • Organic molecules contain carbon.
    • Functional groups give molecules unique properties and alter their function in cells.
    • Biological molecules are complex organic compounds built from monomers.

    Carbohydrates

    • Carbohydrates are made of carbon, hydrogen, and oxygen.
    • Monosaccharides are the monomers of carbohydrates joined by dehydration synthesis, forming glycosidic linkages.
    • Disaccharides are formed from two monosaccharides, while polysaccharides are formed from many monosaccharides.
    • Glycogen is a branched chain of glucose monomers serving as storage in animals.
    • Starches are linear chains of glucose monomers used for storage in plants.

    Lipids

    • Lipids are hydrophobic molecules made of carbon, hydrogen, and a small proportion of oxygen.
    • Examples include fatty acids, triglycerides, phospholipids, steroids, eicosanoids, and fat-soluble vitamins.
    • Saturated fatty acids have only single bonds between carbons.
    • Unsaturated fatty acids have double bonds between carbons.
    • Triglycerides are made of three fatty acids bonded to a glycerol backbone.
    • Phospholipids are amphipathic molecules, containing both hydrophilic and hydrophobic regions.
    • Steroids are made of four fused carbon rings.
    • Eicosanoids are involved in immune signaling, such as prostaglandins and leukotrienes.
    • There is no single monomer in lipids.

    Proteins

    • Proteins are large molecules made of carbon, hydrogen, oxygen, and nitrogen.
    • Amino acids are the monomers of proteins, each with a unique R group.
    • Amino acids connect through peptide bonds formed by dehydration synthesis.
    • Small proteins may consist of a single polypeptide chain, while larger proteins may be made of multiple polypeptide chains.
    • Protein structure is determined by the sequence of amino acids, the repeated folds, and the three-dimensional shape.
    • Denatured proteins lose their structure and become biologically inactive.

    Enzymes

    • Biological catalysts that accelerate chemical reactions without being consumed by the reaction
    • Non-protein molecules that assist enzyme catalysis are called cofactors
    • Cofactors that are organic molecules are called coenzymes
    • Chemical reactions would be too slow or not even happen in the human body without enzymes

    How Enzymes Work

    • Substrates bind the active site, forming the substrate-enzyme complex
    • Chemical reaction is performed: bonds are made/broken and atoms are rearranged
    • The reaction products are released, freeing the enzyme to act on more substrate
    • Enzymes increase the rate of chemical reactions by lowering the activation energy for the reaction

    Characteristics of Enzymes

    • Highly specific:
      • Reactants in enzyme-catalyzed reactions are called substrates
      • Chemical reactions are performed on the enzyme at the active site
      • Substrates fit the active sites of enzymes through a “lock and key” mechanism
    • Efficient:
      • Because they lower activation energy, enzymes increase the rate of chemical reactions
      • Activation energy is the amount of energy required to break a bond
    • Regulated:
      • Cells control the synthesis and activity of enzymes
      • Proenzymes are inactive forms of enzymes that must be processed under the right conditions to be active
        • For example, prothrombin is the inactive form of thrombin which is involved in blood clotting

    Nucleic Acids

    • Made of carbon, hydrogen, oxygen, nitrogen, and phosphorus
    • Can be either deoxyribonucleic acid (DNA) or ribonucleic acid (RNA)
    • Genes are made of DNA
    • Genes are a section of the DNA that makes a specific protein
    • DNA is transcribed to RNA
    • RNA is translated by ribosomes to proteins
    • Monomers are called nucleotides, which are made of a:
      • Nitrogenous base
      • Pentose sugar
      • Phosphate group

    DNA and RNA

    • DNA contains A, G, C, and T
    • RNA contains A, G, C, and U
    • A and G are purines = double-ring bases
    • T and C are pyrimidines = single-ring bases
    • One purine pairs with one pyrimidine
    • In DNA, the pentose sugar = deoxyribose
    • In RNA, the pentose sugar = ribose
    • The phosphate groups + pentose sugars = backbone of the molecule
    • Due to the properties of nucleotides, DNA forms a double helix:
      • Proposed in 1953 by James Watson and Francis Crick
      • Bases form the “rungs”

    DNA

    • DNA is the genetic material of all living things
    • DNA replication makes a new copy of the double helix using one strand as a template
    • A change in the nucleotide sequence of DNA is called a mutation

    RNA

    • RNA is single-stranded
    • There are three major types of RNA:
      • Messenger RNA (mRNA)
      • Ribosomal RNA (rRNA)
      • Transfer RNA (tRNA)

    Adenosine Triphosphate

    • Adenosine triphosphate (ATP) is the energy currency of cells
    • Consists of three phosphate groups bound to adenosine (adenine + ribose)
    • ATP is produced by exergonic cellular reactions
    • ATP is consumed by endergonic cellular reactions to do cellular work
    • The loss of the terminal phosphate by hydrolysis releases a large amount of energy
    • ATP can be regenerated!
    • The synthesis of ATP is catalyzed by ATP synthase during aerobic cellular respiration

    Cells: The Basic Unit of Life

    • Cells come in various shapes and sizes, with over 200 different types in the human body.
    • Each cell has a specialized structure that reflects its unique function.
    • The cell is the fundamental unit of life, organizing into tissues, organs, and organ systems.
    • Organelles are small, specialized subunits within cells, like miniature organs, responsible for specific functions.
    • Some organelles are membrane-bound, like mitochondria, while others are not, like ribosomes.
    • Only eukaryotic cells possess membranous organelles.

    Eukaryotic Cell Organelles

    • The plasma membrane acts as a flexible barrier, separating the cell's internal environment from the external environment.
    • It regulates the exchange of materials with the environment and enables communication between cells.
    • The cytoplasm encompasses the fluid between the plasma membrane and the nucleus, providing a medium for cellular reactions.
    • The cytoskeleton is a network of protein filaments that shapes, stabilizes, and facilitates movement of cells and internal structures.

    Cytoskeleton Components

    • Microfilaments, composed of actin and myosin, contribute to cell movement and structural support, forming microvilli.
    • Intermediate filaments, made of various protein subunits, provide tensile strength and anchor organelles like the nucleus.
    • Microtubules, constructed of tubulin, dynamically assemble and disassemble, playing roles in chromosome segregation during cell division and forming cilia and flagella for cell movement.

    Centrosome

    • The centrosome serves as the microtubule-organizing center in animal cells.
    • It contains centrioles, short microtubules crucial for forming the mitotic spindle during mitosis.

    Cilia and Flagella

    • Cilia are short bundles of microtubules that beat like oars, found in the upper respiratory tract and oviduct.
    • Flagella are long bundles of microtubules that move in a whip-like fashion, propelling cells like sperm.

    Nucleus

    • The nucleus is a membranous organelle containing DNA, the blueprint for cellular proteins.
    • The nuclear envelope, composed of two membranes, encloses the nucleus.
    • Nuclear pores allow the passage of mRNAs and ribosomal subunits out of the nucleus.
    • The nucleolus is a dense region responsible for making ribosomal subunits.

    DNA Packaging

    • DNA must be organized to fit within the cell and be moved during cell division.
    • In its loose, thread-like form, DNA is called chromatin, allowing gene transcription.
    • When condensed into tightly wound chromosomes, genes are inaccessible for transcription.
    • The genome encompasses all the DNA in an organism.

    Ribosomes

    • Ribosomes, composed of rRNA and protein, are responsible for translating mRNA into proteins.
    • Each ribosome consists of a large and a small subunit, assembled in the cytoplasm.
    • Some ribosomes attach to the rough endoplasmic reticulum membrane.

    Central Dogma of Biology

    • This describes the flow of genetic information in cells.
    • DNA sequences called genes encode information to create proteins.
    • Genes are transcribed into mRNA.
    • mRNA is translated by ribosomes into proteins.
    • In human cells, transcription occurs within the nucleus, while translation takes place at the ribosome.

    Ribosome Function

    • Ribosomes translate mRNA into protein, essentially converting one biomolecule into another.
    • The small and large ribosomal subunits bind to mRNA.
    • tRNAs carry amino acids that match the mRNA triplets, also known as codons.

    Endoplasmic Reticulum

    • The endoplasmic reticulum (ER) is a network of membranes involved in protein translation, modification, and lipid manufacture.
    Rough Endoplasmic Reticulum (rER)
    • Studded with ribosomes, continuous with the nuclear membrane.
    • Synthesizes proteins destined for organelles.
    • Proteins are packaged into vesicles for transport.
    • Exports membranes to other organelles.
    Smooth Endoplasmic Reticulum (sER)
    • Synthesizes lipids like fatty acids and steroids.
    • Inactivates drugs in liver cells.
    • Participates in carbohydrate metabolism.
    • Stores calcium ions.

    Golgi Complex

    • Modifies, sorts, finishes, and packages proteins for delivery.
    • Composed of membranous folds called cisternae.
    • Has distinct entry and exit faces.
    • Proteins are modified (e.g., glycosylated, phosphorylated) and packaged into vesicles for export.

    Lysosomes

    • Spherical, membrane-bound sacs containing digestive enzymes.
    • Pump H+ into the interior, creating an acidic pH (around 5).
    • Breakdown and recycle cellular molecules.

    Tay-Sachs Disease

    • A lysosomal storage disorder caused by defective lysosomes.
    • Leads to seizures and neurological symptoms, typically appearing within 3-6 months after birth.
    • Death is likely before the age of four.

    Peroxisomes

    • Spherical, membrane-bound sacs with a crystalline core.
    • Contain oxidases that metabolize fatty acids and detoxify alcohols.
    • Contain catalase, which breaks down hydrogen peroxide.
    • Handle metabolic byproducts.

    Proteasomes

    • Large, cytoplasmic cellular machines that break down large polypeptides into smaller peptides.
    • Other peptidases further break down peptides into amino acids.
    • Defects in proteasomal function can contribute to diseases like Parkinson’s and Alzheimer’s.

    Mitochondria

    • Bounded by two membranes: inner and outer mitochondrial membranes.
    • The space between the membranes is called the intermembrane space.
    • The inner mitochondrial membrane is folded into cristae.
    • The inner membrane encloses the mitochondrial matrix.
    • Aerobic cellular respiration begins in the cytoplasm and concludes at the inner mitochondrial membrane.

    Aerobic Cellular Respiration

    • The process of extracting chemical potential energy from glucose and storing it as ATP in the presence of oxygen.
    • Starts with glycolysis in the cytoplasm and ends with ATP synthesis at the inner mitochondrial membrane.
    • Summary reaction: C6H12O6 + 6O2 → 6CO2 + 6H2O + 36–38 ATP

    Mitochondrial Fun Facts

    • Mitochondria are maternally inherited, as sperm mitochondria are not allowed into the egg during fertilization.
    • They contain their own DNA, replicating independently of the nuclear genome.
    • Compromised mitochondrial structure can initiate cell death (apoptosis).

    Cell Division

    Somatic Cell Division

    • Somatic cells (all cells except reproductive cells) divide through mitosis and cytokinesis.
    • Mitosis is the division of the nucleus and its contents.
    • Cytokinesis is the division of the remaining cellular components.
    • The cell cycle encompasses the sequence of events during somatic cell division.
    Interphase
    • A period of cell growth with three stages.
    • G1 – cell growth and preparation for DNA replication.
    • S phase – DNA replication in preparation for mitosis.
    • G2 – replication of cytoplasmic components (e.g., mitochondria).

    DNA Replication

    • Occurs during S phase, where strands of DNA separate.
    • DNA polymerase uses one strand as a template to create a new daughter strand.
    • The new molecule is 50% "old" and 50% "new", a process called semi-conservative replication.

    Mitosis

    • Nuclear division, divided into four phases.
    Prophase
    • Dissolution of the nuclear envelope.
    • Condensation of chromatin into chromosomes.
    Metaphase
    • Alignment of chromosomes at the equatorial plate (middle).
    • Attachment of the mitotic spindle.
    Anaphase
    • Pulling of chromosomes to opposite poles of the cell by the mitotic spindle.
    Telophase
    • Partitioning of the nuclear content into two forming daughter cells.

    Cytokinesis

    • Completes cell division by dividing the cytoplasm.

    Chromosome Anatomy

    • An unreplicated chromosome is called a chromosome.
    • A replicated chromosome is also called a chromosome.
    • The two halves are called sister chromatids.
    • The constricted center is called the centromere.
    • The kinetochore, a protein complex around the centromere, serves as the attachment point for the mitotic spindle.

    Telomeres

    • DNA sequences at the ends of chromosomes that protect against shortening.
    • They act as caps to prevent nucleolytic degradation.
    • Added to chromosomes by the enzyme telomerase.

    Telomeres and Aging

    • Telomeres shorten with age, potentially contributing to cellular aging.
    • When telomeres reach a critical length, cell death may occur.
    • Lifestyle choices like smoking and obesity can be associated with shortened telomeres.

    Telomeres and Cancer

    • Cancer cells have overactive telomerase, elongating telomeres, enabling rapid cell division and tumor formation.

    Reproductive Cell Division

    Meiosis

    • Division of reproductive cells into gametes (haploid cells with half the chromosome complement).
    • Two rounds of division: meiosis I and meiosis II.
    Meiosis I
    • Divides replicated chromosomes into daughter cells.
    • Crossing over involves the exchange of genetic information between homologous chromosomes through recombination.
    • Results in two non-identical daughter cells with haploid chromosome sets.
    Meiosis II
    • Separates sister chromatids into two gametes.
    • Results in four non-identical daughter cells with a haploid chromosome set, called gametes.

    Membrane Structure and Function

    Fluid Mosaic Model

    • Describes the fluidity of the plasma membrane.
    • Lipids and some proteins move freely within the membrane.

    Lipid Bilayer

    • The foundation of biological membranes: a sandwich of phospholipid molecules.
    • Phosphate heads are hydrophilic (polar) and face the solvent.
    • Fatty acid tails are hydrophobic (nonpolar) and are protected inside the bilayer.

    Membrane Composition

    • Phospholipids comprise ~75% of the membrane.
    • Cholesterol (~20%) acts as a fluidity buffer.
    • Glycolipids (~5%) are carbohydrate-lipid combinations.

    Membrane Fluidity

    • Essential for membrane function.
    • Influenced by saturation of fatty acid tails, presence of cholesterol, and temperature.
    Fatty Acid Saturation
    • Saturated fatty acids are straight, increasing membrane rigidity.
    • Unsaturated fatty acids contain bends, increasing membrane fluidity.
    Cholesterol
    • Acts as a fluidity buffer.
    • Its bulky nature increases space between lipids, promoting fluidity.
    • Its planar structure restricts lipid movement, decreasing fluidity.

    Selective Permeability

    • Property of membranes that allows only certain solutes to pass through.
    • Nonpolar molecules like O2 and CO2 readily diffuse across the bilayer due to their ability to interact with the hydrophobic core.
    • Polar molecules like proteins and carbohydrates typically do not cross readily.

    Membrane Proteins

    • Embedded within the lipid bilayer, contributing to the mosaic nature of the membrane.
    Integral Membrane Proteins
    • Anchored to the hydrophobic core.
    • Transmembrane proteins span the entire membrane.
    • Amphiphilic in nature, possessing both hydrophilic and hydrophobic regions.
    Peripheral Membrane Proteins
    • Bound to the membrane through electrostatic interactions.
    • Hydrophilic proteins.
    Glycoproteins
    • Membrane proteins attached to saccharides.
    • Found on the extracellular face of the membrane.
    • Glycoproteins and glycolipids together contribute to the glycocalyx.
    Protein Functions in Membranes
    • Receptors: bind specific molecules and signal changes in cell behavior.
    • Enzymes: catalyze chemical reactions.
    • Linker proteins: connect cells and facilitate locomotion.
    • Cell identity markers: usually glycoproteins that distinguish cell types.

    Simple Diffusion

    • Movement of solutes across a membrane from high to low concentration.
    • Passive transport (no energy required).
    • Driven by the concentration gradient.

    Factors Affecting Diffusion Rate

    • Solute size: larger particles diffuse slower.
    • Temperature: higher temperature increases diffusion rate.
    • Concentration gradient: steeper gradient favors faster diffusion.

    Facilitated Diffusion

    • Diffusion aided by transmembrane proteins.
    • Allows movement of charged substances through ion channels.
    • May be gated, requiring a signal or ligand for opening.

    Electrochemical Gradient

    • A combination of concentration gradient and electrical gradient.
    • Charged substances tend to diffuse from high to low concentration and from areas of one charge to areas of opposite charge.

    Carrier Proteins

    • Facilitate diffusion by changing shape to move solutes across the membrane.
    • Move polar, hydrophilic substances down their concentration gradients.
    • Provide a hydrophilic path for polar solutes through the membrane.

    Active Transport

    • Moves substances against their concentration gradients, requiring energy (usually ATP).
    • Maintains specific concentration gradients within the cell.
    • E.g., maintaining the negative membrane potential of most cells (-60 mV).

    Active Transport

    • Moves solutes against their concentration gradients across membranes
    • Requires energy, often provided by ATP hydrolysis
    • Sodium-potassium pump (Na+-K+ pump):
      • Found in animal cells
      • Maintains higher Na+ concentration outside the cell and higher K+ concentration inside the cell.
      • Uses energy from ATP hydrolysis to change shape and move ions
    • Primary active transporters: directly use ATP hydrolysis for transport
    • Secondary active transporters: use electrochemical gradients established by primary transporters for transport.
      • Don't directly use ATP hydrolysis
      • Two solutes are moved simultaneously: one down its concentration gradient, releasing energy to move the other up its concentration gradient.
      • Symporters: both solutes move in the same direction.
      • Antiporters: solutes move in opposite directions.

    Cyanide Inhibition

    • Cyanide blocks ATP production in mitochondria.
    • This disrupts all active transport, including secondary active transport.

    Vesicular Transport

    • Involves membrane sacs (vesicles) that transport materials between organelles.
    • Endocytosis: movement of substances into the cell via vesicles.
    • Exocytosis: movement of substances out of the cell via vesicles.
      • Can be called secretion.
    • Both processes require ATP hydrolysis.
    • Transcytosis: movement of substances through cells, involving both endocytosis and exocytosis.
    • Receptor-mediated endocytosis: specific molecules are imported into cells through receptors on the membrane.
      • Viruses, including HIV, can be endocytosed.
    • Phagocytosis: "eating" of molecules or invaders by phagocytic cells.
      • Substances are engulfed and internalized in a vesicle.
      • Vesicle fuses with lysosome, digesting the contents.
      • Important for immune cells like macrophages and neutrophils.

    Pinocytosis

    • Cell "drinking" of dissolved solutes; also called bulk-phase endocytosis.
    • Large volumes of molecules are imported into a vesicle, which then fuses with a lysosome.
    • Important for immune cells that surveil the body for invaders.

    Osmosis

    • Water moves from a region of low solute concentration to a region of high solute concentration.
    • Occurs across a semi-permeable membrane.
    • Water can move across the lipid bilayer but very inefficiently.
    • Aquaporins: channel proteins that allow water to move across biological membranes efficiently.

    Cells in Different Solutions

    • Hypertonic solution: has a higher solute concentration than the cell.
      • Water moves out of the cell.
    • Hypotonic solution: has a lower solute concentration than the cell.
      • Water moves into the cell.
    • Isotonic solution: has the same solute concentration as the cell.
      • No net water movement.

    Osmolarity and Tonicity

    • Osmolarity: total concentration of all solutes in a solution.
    • Tonicity: describes how a cell behaves when placed in a solution.
    • Osmolarity determines the tonicity of a solution.

    Cell Division

    • Somatic cells: divide by mitosis, producing two identical daughter cells.
    • Reproductive cells: divide by meiosis, producing four nonidentical gametes.

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    This quiz covers the essential components and functions of the integumentary system, including skin, hair, nails, and glands. You'll learn about skin layers, cellular compositions, and the system's vital roles in protecting the body and regulating temperature.

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