[RAP0 21LAB] MIDTERM: Lesson 7

Cell Structure and Function

• Each cell is composed of distinct structures, or organelles, that work together to maintain cellular function.

• These include the cell membrane, cytoplasm, nucleus, and various organelles such as the mitochondria, ribosomes, and endoplasmic reticulum.

• The collective activity of these components ensures proper functioning and homeostasis within the cell.

Cell Membrane and Its Functions

• The cell membrane, also known as the plasma membrane, is a selectively permeable barrier that surrounds the cell.

• Composed of a phospholipid bilayer with embedded proteins, it controls the movement of substances into and out of the cell.

• This membrane also plays a role in cell communication, signaling, and structural support.

Movement Through the Cell Membrane

• Passive Transport

  • Includes diffusion, osmosis, and facilitated diffusion, which move substances across the membrane without requiring energy.

• Active Transport

  • Uses ATP to transport molecules against a concentration gradient through protein pumps.

• Endocytosis and Exocytosis

  • Processes by which large molecules are engulfed into the cell (endocytosis) or expelled (exocytosis).

Passive Transport

• Movement Through the Cell Membrane

• Includes diffusion, osmosis, and facilitated diffusion, which move substances across the membrane without requiring energy.

Active Transport

• Movement Through the Cell Membrane

• Uses ATP to transport molecules against a concentration gradient through protein pumps.

Endocytosis and Exocytosis

• Movement Through the Cell Membrane

• Processes by which large molecules are engulfed into the cell (___) or expelled (___).

Organelles and Their Functions

• Nucleus

  • Contains genetic material (DNA) and controls cellular activities.

• Mitochondria

  • The powerhouse of the cell, responsible for ATP production.

• Ribosomes

  • Synthesize proteins essential for cell function.

• Endoplasmic Reticulum (ER)

  • Rough ER: Studded with ribosomes and aids in protein synthesis.

  • Smooth ER: Involved in lipid synthesis and detoxification.

• Golgi Apparatus

  • Modifies, sorts, and packages proteins and lipids.

• Lysosomes

  • Contain enzymes for digestion and waste removal.

• Cytoskeleton

  • Provides structural support and facilitates movement.

Nucleus

• Organelles and Their Functions

• Contains genetic material (DNA) and controls cellular activities.

Mitochondria

• Organelles and Their Functions

• The powerhouse of the cell, responsible for ATP production.

Ribosomes

• Organelles and Their Functions

• Synthesize proteins essential for cell function.

Endoplasmic Reticulum (ER)

• Organelles and Their Functions

• Rough ER: Studded with ribosomes and aids in protein synthesis.

• Smooth ER: Involved in lipid synthesis and detoxification.

Rough ER

• Endoplasmic Reticulum (ER)

• Studded with ribosomes and aids in protein synthesis.

Smooth ER

• Endoplasmic Reticulum (ER)

• Involved in lipid synthesis and detoxification.

Golgi Apparatus

• Organelles and Their Functions

• Modifies, sorts, and packages proteins and lipids.

Lysosomes

• Organelles and Their Functions

• Contain enzymes for digestion and waste removal.

Cytoskeleton

• Organelles and Their Functions

• Provides structural support and facilitates movement.

Whole Cell Activity

• Cells function as dynamic systems, responding to environmental stimuli and maintaining homeostasis.

• Cellular activities include:

  • Metabolism

  • Cell Communication

  • Cell Division

Metabolism

• Whole Cell Activity

• The sum of all chemical reactions, including catabolic (breakdown) and anabolic (synthesis) processes.

Cell Communication

• Whole Cell Activity

• Signals transmitted through chemical messengers help coordinate cellular responses.

Cell Division

• Whole Cell Activity

• Mitosis (for growth and repair) and meiosis (for reproduction) ensure continuity of life.

Cellular Aspects of Aging

• As cells age, they experience changes that affect their function and viability.

• Key aspects include:

  • Telomere Shortening

  • Accumulation of Damage

  • Reduced Regeneration

  • Autophagy and Apoptosis

Telomere Shortening

• Cellular Aspects of Aging

• Repeated cell divisions lead to shortened telomeres, contributing to aging and cell death.

Accumulation of Damage

• Cellular Aspects of Aging

• Oxidative stress and DNA mutations can impair cellular function.

Reduced Regeneration

• Cellular Aspects of Aging

• Stem cell activity declines, reducing the body's ability to repair tissues.

Autophagy and Apoptosis

• Cellular Aspects of Aging

• Mechanisms that remove damaged cells become less efficient with age.

Tissue and Histology

• Tissues are groups of similar cells that perform a common function.

• Histology, the study of tissues, is a branch of microscopic anatomy that helps us understand tissue structure, function, and pathology.

• There are four primary tissue types in the human body: epithelial, connective, muscular, and nervous tissue.

Epithelial Tissue

• These forms the protective covering of body surfaces, lines cavities, and forms glands.

• It is characterized by closely packed cells with minimal extracellular material.

• Depending on its function and location, it can be classified into simple (single-layered) or stratified (multi-layered) epithelium.

• Specialized types include squamous, cuboidal, columnar, and pseudostratified epithelium.

• This plays roles in protection, absorption, secretion, and sensation.

Connective Tissue

• It provides support, binds structures, and plays a role in transportation and immunity.

• It consists of cells dispersed in an extracellular matrix composed of protein fibers (collagen, elastic, and reticular) and ground substance.

• Types of this include loose (areolar, adipose, and reticular), dense (regular and irregular), cartilage, bone, and blood.

• It functions in structural support, energy storage, defense, and tissue repair.

Muscular Tissue

• It is specialized for contraction, enabling movement.

• It consists of three types: skeletal muscle (voluntary, striated, attached to bones), cardiac muscle (involuntary, striated, found in the heart), and smooth muscle (involuntary, non-striated, found in walls of hollow organs).

• Muscles generate force and movement through the contraction of actin and myosin filaments.

Nervous Tissue

• It is responsible for transmitting electrical signals and processing information.

• It consists of neurons, which conduct impulses, and neuroglia, which support and protect neurons.

• The brain, spinal cord, and peripheral nerves are composed of nervous tissue, playing critical roles in sensory input, motor output, and coordination of body functions.

Membranes

• Body ___ are structures composed of epithelial and/or connective tissues that cover surfaces, line cavities, and protect organs.

• The four main types are mucous ___ (line cavities that open to the exterior, e.g., respiratory and digestive tracts), serous ___ (line closed body cavities and cover organs), cutaneous ___ (skin), and synovial ___ (line joint cavities and secrete lubricating fluid).

Tissue Damage and Inflammation

• Tissue damage can result from trauma, infection, toxins, or autoimmune responses.

• The body's immediate response is inflammation, characterized by redness, heat, swelling, pain, and loss of function.

• Inflammation serves to isolate the injury, remove pathogens, and initiate repair mechanisms.

• Key components of the inflammatory response include histamine release, increased blood flow, and immune cell activation.

Tissue Repair

• It occurs through two main processes: regeneration (replacement with the same tissue type) and fibrosis (replacement with scar tissue).

• The repair process involves three phases: inflammation, proliferation (formation of new tissue and blood vessels), and remodeling (strengthening of new tissue).

• Epithelial and connective tissues regenerate well, whereas nervous and cardiac muscle tissues have limited regenerative capacity.

Effects of Aging on Tissue

• Aging affects tissue structure and function, leading to decreased elasticity, slower healing, and increased susceptibility to disease.

• Collagen production declines, making connective tissues stiffer.

• Epithelial tissues become thinner, reducing protective barriers.

• Muscular tissue loses mass and strength, while nervous tissue may experience slower signal transmission due to neuron loss.

• These changes contribute to reduced organ function and overall decline in health.

Function of the Integumentary System

• The integumentary system, primarily composed of the skin, serves as the body's first line of defense.

• It protects against physical, chemical, and biological threats while also regulating body temperature, preventing dehydration, and enabling sensory perception.

• Additionally, it plays a role in immune response and vitamin D synthesis, which is essential for calcium absorption.

Skin

• It is the largest organ of the body and consists of three main layers:

  • Epidermis

  • Dermis

  • Hypodermis (subcutaneous tissue)

Epidermis

• Skin

• The outermost layer, primarily composed of keratinized stratified squamous epithelium.

• It provides a barrier against environmental hazards.

Dermis

• Skin

• Located beneath the epidermis, this layer contains connective tissue, blood vessels, nerve endings, hair follicles, and sweat glands.

Hypodermis (subcutaneous tissue)

• Skin

• A deeper layer that connects the skin to underlying structures and provides insulation and cushioning.

Subcutaneous Tissue

• Also known as the hypodermis, is composed mainly of adipose tissue and connective tissue.

• It functions as an insulator, stores energy, and acts as a shock absorber to protect internal organs from mechanical trauma.

• Additionally, it contains blood vessels that supply the skin and plays a role in thermoregulation.

Accessory Skin Structures

• The skin has several important accessory structures that aid in its functions:

  • Hair

  • Sebaceous (oil) glands

  • Sweat glands

  • Nails

Hair

• Accessory Skin Structures

• Provides protection, reduces heat loss, and facilitates sensory perception.

Sebaceous (oil) glands

• Accessory Skin Structures

• Secrete sebum to lubricate and waterproof the skin.

Sweat glands

• Accessory Skin Structures

• Aid in thermoregulation and excretion of metabolic waste.

Nails

• Accessory Skin Structures

• Protect the distal ends of fingers and toes and assist in grasping objects.

Physiology of the Integumentary System

• The integumentary system performs several vital physiological functions:

  • Protection

  • Thermoregulation

  • Sensation

  • Excretion

  • Vitamin D Synthesis

Protection

• Physiology of the Integumentary System

• Acts as a barrier against mechanical injuries, pathogens, and UV radiation.

Thermoregulation

• Physiology of the Integumentary System

• Maintains body temperature through sweat production and blood flow regulation.

Sensation

• Physiology of the Integumentary System

• Contains nerve receptors for touch, temperature, and pain.

Excretion

• Physiology of the Integumentary System

• Eliminates small amounts of waste through sweat.

Vitamin D Synthesis

• Physiology of the Integumentary System

• Helps in the production of vitamin D when exposed to sunlight.

Integumentary System as a Diagnostic Aid

• The skin serves as a visible indicator of various systemic diseases and conditions.

• Changes in skin color, texture, or integrity can signal underlying health issues.

• For example:

  • Jaundice (yellowing of the skin)

  • Pallor (pale skin)

  • Cyanosis (bluish skin)

  • Rashes and lesions

Jaundice

• Integumentary System as a Diagnostic Aid

• (yellowing of the skin)

• It may indicate liver disease.

Pallor

• Integumentary System as a Diagnostic Aid

• (pale skin)

• It can suggest anemia or circulatory problems.

Cyanosis

• Integumentary System as a Diagnostic Aid

• (bluish skin)

• It may be a sign of inadequate oxygenation.

Rashes and lesions

• Integumentary System as a Diagnostic Aid

• It can be manifestations of infections, allergic reactions, or autoimmune diseases.

Burns

• They are classified based on severity:

  • First-degree burns: Affect only the epidermis, causing redness and pain.

  • Second-degree burns: Extend into the dermis, leading to blisters and more severe pain.

  • Third-degree burns: Damage all skin layers and underlying structures, often requiring skin grafts. Severe burns can lead to fluid loss, infection, and systemic complications requiring medical intervention.

First-degree burns

Affect only the epidermis, causing redness and pain.

Second-degree burns

Extend into the dermis, leading to blisters and more severe pain.

Third-degree burns

• Damage all skin layers and underlying structures, often requiring skin grafts.

• Severe burns can lead to fluid loss, infection, and systemic complications requiring medical intervention.

Skin Cancer

• It is one of the most common types of cancer and is primarily caused by excessive UV exposure.

• The three main types are:

  • Basal cell carcinoma (BCC)

  • Squamous cell carcinoma (SCC)

  • Melanoma

Basal cell carcinoma (BCC)

• Skin Cancer

• The most common and least aggressive type.

Squamous cell carcinoma (SCC)

• Skin Cancer

• More aggressive than BCC and can spread if untreated.

Melanoma

• The most dangerous type, characterized by uncontrolled melanocyte growth, with a high potential for metastasis.

• Early detection and prevention, including the use of sunscreen and regular skin checks, are crucial in reducing the risk of skin cancer.

Effects of Aging on the Integumentary System

As the body ages, several changes occur in the integumentary system:

• Thinning of the epidermis

• Reduction in collagen and elastin

• Decreased oil production

• Reduced sweat gland activity

• Slower wound healing

Thinning of the epidermis

• Effects of Aging on the Integumentary System

• Makes the skin more fragile and prone to injury.

Reduction in collagen and elastin

• Effects of Aging on the Integumentary System

• Leads to wrinkles and sagging.

Decreased oil production

• Effects of Aging on the Integumentary System

• Results in drier skin.

Reduced sweat gland activity

• Effects of Aging on the Integumentary System

• Impairs thermoregulation, increasing susceptibility to heat-related conditions.

Slower wound healing

• Effects of Aging on the Integumentary System

• Due to decreased cell turnover and blood circulation.

• These age-related changes highlight the importance of skincare and maintaining overall health to preserve skin integrity.

Function of the Skeletal System

• The skeletal system provides the framework for the human body, supporting organs and tissues.

• It serves multiple functions:

  • Support

  • Protection

  • Movement

  • Mineral Storage

  • Blood Cell Production

  • Energy Storage

Support

• Function of the Skeletal System

• Provides a structural framework for the body.

Protection

• Function of the Skeletal System

• Shields vital organs (e.g., skull protects the brain, rib cage protects the heart and lungs).

Movement

• Function of the Skeletal System

• Acts as a system of levers that work with muscles for movement.

Mineral Storage

• Function of the Skeletal System

• Stores calcium and phosphate, which are essential for bodily functions.

Blood Cell Production

• Function of the Skeletal System

• Red bone marrow produces red and white blood cells.

Energy Storage

• Function of the Skeletal System

• Yellow marrow stores fat, serving as an energy reserve.

Extracellular Matrix

Bone tissue consists of an ___ that provides strength and flexibility:

• Organic Components (Collagen and Proteins):

  • Provide tensile strength and flexibility.

• Inorganic Components (Hydroxyapatite - Calcium and Phosphate Crystals):

  • Provide hardness and resistance to compression.

Organic Components (Collagen and Proteins)

• Extracellular Matrix

• Provide tensile strength and flexibility.

Inorganic Components (Hydroxyapatite - Calcium and Phosphate Crystals)

• Extracellular Matrix

• Provide hardness and resistance to compression.

General Features of Bone

• Bones are classified into different shapes and structures:

  • Long Bones

  • Short Bones

  • Flat Bones

  • Irregular Bones

  • Sesamoid Bones

Long Bones

Found in limbs (e.g., femur, humerus) and function in support and movement.

Short Bones

Found in the wrist and ankle, providing stability with minimal movement.

Flat Bones

Found in the skull, sternum, and ribs, protecting internal organs.

Irregular Bones

Found in the vertebrae and certain skull bones, providing specialized functions.

Sesamoid Bones

Embedded in tendons, like the patella, reducing friction in joints.

Bone and Calcium

Calcium plays a crucial role in:

• Bone Mineralization

• Muscle Contraction

• Nerve Function

• Blood Clotting

• Parathyroid Hormone (PTH)

• Calcitonin

• Vitamin D

Bone Mineralization

• Bone and Calcium

• Essential for bone strength.

Muscle Contraction

• Bone and Calcium

• Regulated by calcium ions.

Nerve Functions

• Bone and Calcium

• Facilitates neurotransmission.

Blood Clotting

• Bone and Calcium

• Required for coagulation. Regulation occurs via hormones

Parathyroid Hormone (PTH)

• Bone and Calcium

• Increases calcium levels by stimulating bone resorption.

Calcitonin

• Bone and Calcium

• Lowers calcium levels by inhibiting osteoclast activity.

Vitamin D

• Bone and Calcium

• Enhances calcium absorption in the intestines.

General Considerations of Bone Anatomy

• Compact Bone

• Spongy Bone (Cancellous Bone)

• Periosteum

• Endosteum

• Medullary Cavity

Compact Bone

• General Considerations of Bone Anatomy

• Dense outer layer providing strength

Spongy Bone (Cancellous Bone)

• General Considerations of Bone Anatomy

• Lighter, porous inner structure housing bone marrow.

Periosteum

• General Considerations of Bone Anatomy

• Outer fibrous covering aiding in growth and repair.

Endosteum

• General Considerations of Bone Anatomy

• Inner membrane lining the medullary cavity.