Chapter 4,5,6 notes

Chapter 4

• Describe how lipids and proteins are distributed in the plasma membrane and explain the functions of each

  • Lipids:

    • Phospholipids: form the bilayer; hydrophilic heads face outward, hydrophobic tails face inward. Create a selective barrier and provide membrane fluidity

    • Cholesterol: Stabilizes membrane fluidity, preventing it from becoming too rigid or permeable

    • Glycolipids: Located on the outer surface; involved in cell recognition and communication

  • Proteins:

    • Integral Proteins: Span the bilayer; act as channels, transporters, or receptors for signaling

    • Peripheral Proteins: Loosely attached; involved in signaling, enzymatic activity and interactions with the cytoskeleton

  • Functions:

    • Structure and Fluidity: Lipids form the foundation and regulate fluidity

    • Transport: Proteins help with moving substances across the membrane

    • Signaling and Communication: Proteins serve as receptors and glycolipids help with cell recognition

• Compare and contrast different processes of membrane transport with respect to type of material transported, mechanism of transport, and energy requirements

  • Simple Diffusion:

    • Materials: Small, nonpolar molecules (e.g. O2, CO2)

    • Mechanism: Moves directly through the bilayer

    • Energy: No energy (passive)

  • Facilitated Diffusion:

    • Materials: Larger, polar molecules (e.g. glucose, ions)

    • Mechanism: Moves through channel or carrier proteins

    • Energy: No energy (passive)

  • Active Transport:

    • Materials: Ions, large molecules (e.g. Na+, K+)

    • Mechanism: Moves against concentration gradient via pumps

    • Energy: Requires ATP (active)

  • Endocytosis:

    • Materials: Large particles, liquids (e.g. nutrients, pathogens)

    • Mechanism: Membrane engulfs material to form a vesicle

    • Energy: Requires ATP (active)

  • Exocytosis:

    • Materials: Large molecules (e.g. proteins, neurotransmitters)

    • Mechanism: Vesicle fuses with membrane to release material

    • Energy: Requires ATP (active)

• Explain the relationship between osmosis, osmotic pressure, and tonicity

  • Osmosis is the process that causes water to move due to differences in solute concentrations, which is measured by osmotic pressure

  • Tonicity defines the effect of a solution on the cell’s size and shape, depending on how the osmotic pressure differences between the solution and the cell’s interior cause water to move in or out

• Describe osmosis, osmotic pressure, and tonicity

  • Osmosis: The movement of water across a selectively permeable membrane from an area of low solute concentration to high solute concentration

  • Osmotic Pressure: The pressure exerted by water as it moves through the membrane during osmosis. More solutes= higher osmotic pressure. Dilutes the higher solute concentration

  • Tonicity: Describes how a solution’s solute concentration compares to that of the cell’s interior, influencing osmosis

  • Types of Tonicity:

    • Isotonic: The solute concentration is the same inside and outside the cell. No net water movement

    • Hypotonic: The solution has a lower solute concentration than inside the cell. Water enters the cell, causing it to swell

    • Hypertonic: The solution has a higher solute concentration than inside the cell. Water leaves the cell, causing it to shrink

• Understand how the resting membrane potential is established and maintained and the role of Na+, K+ and negatively charged proteins in the establishment of the RMP

  • What is RMP: RMP is the electrical charge difference across the cell membrane when the cell is at rest, typically -70 mV

  • Key Players:

    • Na+: (sodium) is high outside the cell

    • K+: (potassium) is high inside the cell

    • Negatively charged proteins are trapped inside the cell, contributing to the negative charge

  • Na+/K+ Pump: Actively pumps 3 Na+ out and 2 K+ in, creating concentration gradients

  • K+ Leak: The membrane is more permeable to K+, which leaks out, making the inside of the cell negative

  • Maintaining RMP: The Na+/K+ pump, K+ leakage, and immobile proteins maintain the negative charge inside the cell

  • Summary: The resting membrane potential is the result of the unequal distribution of ions, selective permeability of the membrane, and the action of the Na+/K+ pump, which together maintain a negative internal environment relative to the outside of the cell

• Describe the structure and function of human cell organelles

  • Nucleus:

    • Structure: Membrane-bound, contains nuclear envelope with pores. Inside is chromatin and nucleolus

    • Function: Contains DNA, controls cell activities and regulates gene expression

  • Mitochondria:

    • Structure: Double membrane; inner membrane folds into cristae

    • Function: Produces energy (ATP) through cellular respiration, known as the “powerhouse” of the cell

  • Endoplasmic Reticulum (ER):

    • Structure: Network of membranes, rough ER has ribosomes, smooth ER lacks ribosomes

    • Function: Rough ER synthesizes proteins, smooth ER synthesizes lipids and detoxifies harmful substances

  • Golgi Apparatus:

    • Structure: Stack of flattened sacs (cisternae)

    • Function: Modifies, sorts, and packages proteins and lipids for transport or secretion

  • Ribosomes:

    • Structure: Small, composed of RNA and protein; found free in the cytoplasm or attached to the rough ER

    • Function: Synthesizes proteins by translating mRNA

  • Lysosomes:

    • Structure: Membrane-bound sacs containing digestive enzymes

    • Function: Breaks down waste, cellular debris, and foreign materials via digestion (autophagy)

  • Peroxisomes:

    • Structure: Network of protein filaments (microtubules, microfilaments, and intermediate filaments)

    • Function: Provides structural support, enables cell movement, and aids in intracellular transport

  • Centrioles:

    • Structure: Cylindrical structures made of microtubules

    • Functions: Helps in cell division by organizing the mitotic spindle

  • Vacuoles:

    • Structure: Membrane-bound sacs, larger in plant cells, but also present in animal cells

    • Function: Stores nutrients, waste products, and helps maintain cell shape

  • Plasma Membrane:

    • Structure: Phospholipid bilayer with embedded proteins

    • Function: Protects the cell, controls what enters and exits, and allows communication with other cells

• Compare and contrast the 3 types of cell to cell junctions

  • Differences

    • Tight Junctions:

      • Structure: Tight seals between cells

      • Function: Prevents leakage of substances between cells, forming a barrier

    • Adherens Junctions:

      • Structure: Link cells via cadherins connected to actin filaments

      • Function: Provides structural support and helps cells stick together, forming tissues

    • Desmosomes:

      • Structure: Cadherins linked to intermediate filaments (keratin)

      • Function: Resists mechanical stress and provides strong cell-to-cell adhesion

  • Similarities:

    • All involve proteins that bind adjacent cells together

    • All contribute to the structural integrity and function of tissues

• Describe the processes of transcription and translation

  • Transcription

    • Location: Nucleus

    • Process: RNA polymerase copies DNA into mRNA

    • Steps:

      • 1. RNA polymerase binds to DNA and unwinds it

      • 2. mRNA is synthesized complementary to the DNA template

      • 3. mRNA is released when the process is complete

  • Translation

    • Location: Ribosome (cytoplasm)

    • Process: mRNA is used to build a protein

    • Steps:

      • 1. Ribosome binds to mRNA and starts at the codon (AUG)

      • 2. tRNA brings amino acids, forming a polypeptide chain

      • 3. Chain is released when a codon is reached

  • Summary:

    • Transcription converts DNA to mRNA in the nucleus

    • Translation converts mRNA into a protein in the ribosome

• Describe the major events of the cell cycle including Telophase (G1, S, G2) and M phase (Prophase, Metaphase, Anaphase, Telophase)

  • Interphase: Cell prepares for division and undergoes growth and DNA replication

    • G1 Phase (Gap 1):

      • Cell grows, synthesizes proteins, and carries out its normal functions

      • Prepares for DNA replication

    • S Phase (Synthesis):

      • DNA is replicated, so each chromosome now consists of two sister chromatids

    • G2 Phase (Gap 2):

      • The cell continues to grow and prepares for mitosis by synthesizing proteins required for cell division

  • M Phase (Mitosis): Phase where cell division occurs. It has 5 stages:

    • Prophase:

      • Chromosomes condense and become visible

      • The nuclear envelope starts to break down

      • Mitotic spindle begins to form

    • Metaphase

      • Chromosomes align along the metaphase plate (equator)

      • Spindle fibers attach to the centromeres of the chromosomes

    • Anaphase:

      • Sister chromatids are pulled apart toward opposite poles of the cell

    • Telophase

      • Chromatids (now individual chromosomes) begin to de-condense

      • Nuclear envelope re-forms around each set of chromosomes

      • Mitotic spindle disassembles

  • Summary:

    • Interphase: Cell growth, DNA replication, preparation for division

    • M Phase: Process of mitosis where the cell’s chromosomes are divided and separated into 2 daughter cells

Chapter 5

• Contrast the general features of the four major tissue types

  • Epithelial tissue:

    • Structure: Closely packed cells, forming sheets

    • Function: Protects, absorbs, secretes

    • Ex: Skin, digestive lining

  • Connective tissue:

    • Structure: Cells widely spaced with abundant extracellular matrix

    • Function: Supports, binds, protects, transports

    • Ex: Bone, blood, cartilage

  • Muscle Tissue:

    • Structure: Cells capable of contraction (skeletal, cardiac, smooth)

    • Function: Facilitates movement

    • Ex: Skeletal muscles, heart, digestive organs

  • Nervous Tissue:

    • Structure: Neurons and supporting cells (neuroglia)

    • Function: Transmits electrical impulses

    • Ex: Brain, spinal cord, nerves

• Describe the structure, function, and location of different epithelial tissues

  • Simple Squamous Epithelium:

    • Structure: Single layer of flat cells

    • Function: Diffusion, filtration

    • Location: Lungs (alveoli), blood vessels, kidneys

  • Simple Cuboidal Epithelium:

    • Structure: Single layer of cube-shaped cells

    • Function: Secretion, absorption

    • Location: Kidney tubules, glands

  • Simple Columnar Epithelium:

    • Structure: Single layer of tall cells (often with microvilli or cilia)

    • Function: Secretion, absorption

    • Location: Stomach, intestines, fallopian tubes

  • Pseudostratified Columnar Epithelium:

    • Structure: Appears layered, but all cells touch the basement membrane

    • Function: Secretion, mucus movement (cilia)

    • Location: Trachea, respiratory tract

  • Stratified Squamous Epithelium:

    • Structure: Multiple layers of flat cells

    • Function: Protection from abrasion

    • Location: Skin, mouth, esophagus

  • Stratified Columnar Epithelium:

    • Structure: Multiple layers of tall cells

    • Function: Protection, secretion

    • Location: Male urethra, large glands

  • Transitional Epithelium

    • Structure: Layers of cells that stretch (cuboidal to squamous)

    • Function: Stretches to accommodate volume changes

    • Location: Bladder, ureters

• Describe the structure, function, and location of different connective tissues

  • Areolar:

    • Structure: Loose fibers (collagen, elastin), fibroblasts

    • Function: Cushions, supports, provides nutrients

    • Location: Under epithelial tissue, around organs

  • Adipose:

    • Structure: Fat cells (adipocytes)

    • Function: Energy storage, insulation, protection

    • Location: Under skin, around organs

  • Reticular:

    • Structure: Reticular fibers, scattered cells

    • Function: Supports organs

    • Location: Lymph nodes, spleen, bone marrow

  • Dense Regular:

    • Structure: Parallel collagen fibers

    • Function: Resists pulling in one direction

    • Location: Tendons, ligaments

  • Dense Irregular:

    • Structure: Irregularly arranged collagen fibers

    • Function: Resists tension in all directions

    • Location: Skin, joint capsules

  • Elastic:

    • Structure: Elastin fibers

    • Function: Stretch and recoil

    • Location: Arteries, lungs, vocal cords

  • Hyaline Cartilage:

    • Structure: Smooth, clear matrix with collagen

    • Function: Supports, reduces friction

    • Location: Joints, nose, ribs

  • Elastic Cartilage:

    • Structure: More elastin fibers

    • Function: Flexible support

    • Location: Ear, epiglottis

  • Fibrocartilage:

    • Structure: Dense collagen fibers

    • Function: Shock absorption

    • Location: Intervertebral discs, knees

  • Bone (osseous tissue):

    • Structure: Collagen fibers, mineralized matrix

    • Function: Support, protection, movement

    • Location: Skeleton

  • Blood:

    • Structure: Plasma, red/white blood cells, platelets

    • Function: Transport, immunity, clotting

    • Location: Blood vessels, heart

• Describe the structure, function and location of different muscle tissues

  • Skeletal:

    • Structure: Long, striated, multinucleated

    • Function: Voluntary movement, posture

    • Location: Attached to bones

  • Cardiac:

    • Structure: Branched, striated, single nucleus, intercalated discs

    • Functions: Involuntary heart contractions

    • Location: Heart

  • Smooth:

    • Structure: Spindle-shaped, non striated, single nucleus

    • Function: Involuntary movement of organs

    • Locations: Walls of hollow organs (e.g. intestines, blood vessels)

• Describe the composition and function of nervous tissue

  • Composition:

    • Neurons: Cells that transmit electrical signals. Contains: axon, dendrites, and cell body

    • Neuroglia: Support cells (e.g. astrocytes, oligodendrocytes)

  • Function:

    • Neurons: Transmit impulses for communication

    • Neuroglia: Support and protect neurons

  • Location:

    • Brain, spinal cord, nerves

• Classify exocrine glands based on form or method of secretion

  • Form:

    • Unicellular: Single-celled (e.g. goblet cells in the intestines)

    • Multicellular: Made of multiple cells (e.g. swear glands)

  • Method of Secretion:

    • Merocrine: Secretion via exocytosis (no cell damage) (e.g. salivary glands, pancreas)

    • Apocrine: Part of the cell’s cytoplasm is pinched off during secretion (e.g. mammary glands)

    • Holocrine: Entire cell ruptures to release secretion (e.g. sebaceous glands (oil))

• Describe the structure, function, and location of different body membranes

  • Mucous Membrane:

    • Structure: Epithelial tissue with connective tissue

    • Function: Line cavities open to the exterior, secrete mucus

    • Location: Respiratory, digestive, urinary, reproductive tracts

  • Serous Membranes:

    • Structure: Simple squamous epithelium with connective tissue

    • Function: Line closed body cavities, reduce friction

    • Location: Pleura, pericardium, peritoneum

  • Cutaneous Membrane (Skin):

    • Structure: Stratified squamous epithelium and connective tissue

    • Function: Protects, regulates temperature

    • Location: Outer body surface

  • Synovial Membranes:

    • Structure: Connective tissue without epithelium

    • Function: Lubricates joints

    • Location: Joint cavities

Chapter 6

• Identify and describe (structure and function) the layers of the epidermis

  • Stratum Basale (Basal layer):

    • Structure: Single layer of cells, includes melanocytes

    • Function: Cell division, melanin production

  • Stratum Spinosum (Spiny layer):

    • Structure: Several layers of polygonal cells
      Function: Strength, flexibility

  • Stratum Granulosum (Granular layer):

    • Structure: 3-5 layers of flattened cells

    • Function: Waterproof barrier, keratin production

  • Stratum Lucidum (Clear Layer):

    • Structure: Thin, clear layer (only in thick skin)

    • Function: Extra protection

  • Stratum Corneum:

    • Structure: Layer of dead, flat cells

    • Function: Protection, waterproofing

• Identify and describe (structure and function) the layers of the dermis

  • Papillary Layer:

    • Structure: Loose connective tissue with dermal papillar

    • Function: Nourishes epidermis, sensory functions

  • Reticular Layer:

    • Structure: Dense connective tissue with collage, elastin, and accessory structures

    • Function: Strength, elasticity, houses glands and hair follicles

• Describe the function of the integumentary system

  • Protection: Defends against damage, chemicals, UV, and pathogens

  • Temperature Regulation: Controls body heat via sweat and blood vessel adjustments

  • Sensation: Detects touch, pain, temperature, and pressure

  • Excretion: Removes waste through sweat

  • Vitamin D Synthesis: Produces vitamin D with sun exposure

  • Water Resistance: Prevents water loss

• Describe the various pigments involved in the skin coloration

  • Melanin: Brown/black pigment; determines skin color and protects against UV

  • Carotene: Yellow-orange pigment; gives a yellow tine, especially in palms/soles

  • Hemoglobin: Red pigment; gives a reddish hue, influenced by blood flow

• Describe the structure of accessory structures in the skin including nails, hair, sweat glands, or sebaceous glands

  • Nails:

    • Structure: Keratinized plates (nail body, bed matrix)

    • Function: Protects fingertips, aids in fine touch

  • Hair:

    • Structure: Keratin shaft, root, follicle, bulb

    • Function: Protection, temperature regulation, sensation

  • Sweat Glands:

    • Structure: Eccrine (cooling) and apocrine (thicker secretion)

    • Function: Thermoregulation and waste removal

  • Sebaceous Glands:

    • Structure: Glands attached to hair follicles, secrete sebum

    • Function: Lubricated skin, prevents dryness