Anatomy and Physiology I: Tissues, Integumentary, and Skeletal Systems

Comprehensive practice flashcards for Anatomy and Physiology I covering Chapter 4 (Tissues and Membranes), Chapter 5 (The Integumentary System), and Chapter 6 (The Skeletal System), featuring question-and-answer pairs and image identification.

What is the biological definition of a tissue, and what are the four major tissue categories in the human body?

A tissue is a group of cells with similar structure and function. The four major categories are epithelial, connective, muscle, and nervous tissue.

How do simple and stratified epithelial tissues differ in cellular arrangement and primary physiological function?

Simple epithelium consists of a single layer of cells specialized for diffusion, absorption, or secretion. Stratified epithelium consists of multiple cell layers specialized to serve as a protective barrier against pathogens and mechanical abrasion.

What are the structural features, locations, and functions of simple squamous epithelium?

It consists of a single layer of flat cells located in capillaries and the alveoli of lungs, functioning in the diffusion of gases and materials and the prevention of blood clotting in the circulatory system.

Where is transitional epithelium located in the human body, and what is its specific function?

It lines the urinary bladder, ureters, urethra, and ducts of the prostate gland; its surface cells change shape from round to squamous to accommodate stretching and prevent tearing of the organ lining.

What are the locations and primary functions of simple cuboidal versus simple columnar epithelium?

Simple cuboidal epithelium lines kidney tubules (absorption) and glands such as salivary and thyroid glands (secretion). Simple columnar epithelium lines the stomach (secretion) and small intestines (secretion and absorption).

What is the primary difference between endocrine and exocrine glands?

Endocrine glands are ductless and secrete hormones directly into the circulatory system or capillaries, whereas exocrine glands have ducts that carry secretions to specific target locations.

Why is the pancreas classified as both an endocrine and an exocrine gland?

It performs an exocrine function by secreting digestive enzymes through ducts into the duodenum of the small intestine, and an endocrine function by secreting insulin and glucagon from the pancreatic islets directly into the bloodstream.

What universal structural characteristic distinguishes all connective tissues from other tissue types?

All connective tissues possess a non-living intercellular matrix or structural network/solution that surrounds the living functional cells.

What constitutes the extracellular matrix of blood, and what is the specific role of platelets?

The matrix of blood is plasma, and platelets function in the prevention of blood loss via blood clotting.

What are the matrix compositions, functional tissues, and bodily locations of fibrous and elastic connective tissues?

Fibrous connective tissue has a matrix of collagen fibers produced by fibroblasts to provide flexible strength in tendons, ligaments, the dermis, and outer artery walls. Elastic connective tissue has an elastin fiber matrix that enables stretching in large artery walls and lung alveoli.

What cells produce and maintain cartilage, and what constitutes cartilage matrix?

Chondrocytes maintain cartilage within a protein-carbohydrate matrix, functioning to prevent friction, absorb shock, and provide support on joint surfaces, the trachea wall, nose, ears, and between vertebrae.

How do skeletal, smooth, and cardiac muscle tissues differ in structure, control, and nucleation?

Skeletal muscle consists of large, striated, multinucleated voluntary cells attached to bones. Smooth muscle has small, non-striated, single-nucleated involuntary tapered cells in organ walls. Cardiac muscle has branched, faintly striated, single-nucleated involuntary cells in the myocardium that can contract independently.

What are the three principal parts of a neuron, and in which directions do they conduct nerve impulses?

The cell body contains the nucleus; dendrites carry impulses toward the cell body; the axon carries impulses away from the cell body across synapses to other neurons, muscles, or glands.

How do serous membranes differ from mucous membranes in location and fluid production?

Serous membranes consist of simple squamous epithelium lining closed body cavities (pleural, pericardial, peritoneal) and secrete serous fluid to prevent friction. Mucous membranes line body tracts opening to the exterior (respiratory, digestive, urinary, reproductive) and secrete mucus to lubricate surfaces and trap particles.

What are the structural and vascular distinctions between the epidermis and the dermis?

The epidermis is the superficial, avascular outer layer composed of stratified squamous keratinizing epithelium. The dermis is the deep, vascular inner layer composed of irregular fibrous connective tissue containing blood vessels and accessory structures.

Which two major structural protein fibers make up the dermal matrix, and which cells produce them?

Collagen and elastin fibers, which provide strength and elasticity respectively, synthesized by dermal fibroblasts.

How do the stratum germinativum and stratum corneum differ in cellular viability and primary physiological functions?

The stratum germinativum (stratum basale) is the living innermost layer where continuous mitosis takes place and vitamin D is synthesized. The stratum corneum is the outermost layer of dead, highly keratinized cells that prevents water loss, chemical entry, and pathogen invasion.

What is the tissue origin and defensive function of epidermal Langerhans cells?

Originating in red bone marrow, Langerhans cells are mobile phagocytes that travel through the epidermis, phagocytize pathogens, and migrate to lymph nodes to present antigens to lymphocytes and trigger an immune response.

Which cutaneous sensations are detected by free nerve endings versus encapsulated nerve endings?

Free nerve endings detect heat, cold, itch, and pain, whereas encapsulated nerve endings detect touch and pressure.

What secretions are produced by sebaceous and ceruminous glands, and where are they located?

Sebaceous glands secrete sebum (oil) into hair follicles across the skin (excluding palms and soles) to lubricate skin and inhibit bacterial growth. Ceruminous glands in the external ear canal secrete cerumen (earwax) to keep the eardrum flexible and create a barrier against foreign matter.

How do eccrine sweat glands differ from apocrine sweat glands in bodily distribution and activation triggers?

Eccrine glands are widely distributed coiled tubular glands (palms, soles, forehead) dedicated to thermoregulation via evaporative cooling. Apocrine glands are confined mainly to axillary and genital areas, activate during stress or emotion, and produce secretions broken down by bacteria into odorous compounds.

How do dermal arterioles adjust blood flow in response to ambient temperature changes versus physiological stress?

Dermal arterioles undergo vasodilation in warm environments to radiate heat away from the body, and vasoconstriction in cold environments to conserve core heat. Under stress, they undergo vasoconstriction to divert blood flow to vital internal organs.

What are the defensive and metabolic roles of the two connective tissues in the subcutaneous layer?

Areolar connective tissue contains white blood cells and mast cells to destroy pathogens entering breaks in the skin. Adipose tissue stores potential energy, provides thermal insulation, cushions bones, and produces cytokines.

What physiological mechanisms cause blisters compared to calluses on the skin?

Excessive friction causes a blister by separating skin layers to form a fluid-filled pocket between the epidermis and dermis. Excessive pressure causes a callus by accelerating mitotic division in the stratum germinativum, thickening the epidermis.

Which degrees of burn injury are shown in this diagram, and what skin layers do each penetrate?

First-degree burns damage only the epidermis. Second-degree burns penetrate into the dermis, causing blisters and pain. Third-degree burns destroy the entire epidermis, dermis, and extend into subcutaneous tissue, destroying nerve endings and rendering the burn initially painless.

How do compact bone and spongy bone differ in histological structure and location within long bones?

Compact bone is composed of osteons (haversian systems) with concentric lamellae around haversian canals and forms the diaphysis. Spongy bone lacks haversian systems, consists of a trabecular network with cavities housing red bone marrow, and is found in the epiphyses and flat/irregular bones.

What specific functions do osteocytes, osteoblasts, and osteoclasts perform in bone physiology?

Osteoblasts synthesize and secrete new bone matrix during ossification. Osteocytes regulate the deposition and withdrawal of calcium from the matrix. Osteoclasts secrete acids and enzymes to resorb bone matrix, forming marrow cavities and remodeling bone.

What anatomical structures of the infant skull are displayed in this diagram, and what functions do they serve?

Fontanels (fibrous connective tissue membranes between cranial bones) that allow compression of the infant head during childbirth and permit brain expansion after birth, closing completely by age $2$.

What is the role of epiphyseal discs in long bone growth, and how do estrogen and testosterone influence their closure?

Epiphyseal discs are cartilaginous growth plates between the diaphysis and epiphysis where chondrocytes produce cartilage and osteoblasts replace it with bone. Estrogen and testosterone accelerate ossification until the cartilage is completely replaced by bone matrix between ages $16$ and $25$, stopping longitudinal bone growth.

Which hormones stimulate bone growth and protein synthesis versus those regulating blood and bone calcium concentrations?

Growth hormone and thyroxine stimulate general bone growth and protein synthesis. Parathyroid hormone and calcitonin regulate calcium homeostasis by modulating mineral resorption from and deposition into bone matrix.

What percentage of the body's calcium and phosphorus reserves are stored within skeletal bone tissue?

Approximately $99\%$ of the body's calcium and $85\%$ of its phosphorus are stored in bone tissue.

Which irregular cranial bone is depicted in this photograph, recognized by its distinct bat-like shape?

The sphenoid bone, which forms part of the floor of the cranium and houses the sella turcica.

What is the only movable facial bone of the skull, and what joint does it form?

The mandible, which forms a condyloid joint with each temporal bone.

How many vertebrae make up each structural region of the human vertebral column?

There are $7$ cervical vertebrae, $12$ thoracic vertebrae, $5$ lumbar vertebrae, $1$ sacrum (fused), and $1$ coccyx (composed of $4$ to $5$ fused vertebrae).

How do the atlas and axis vertebrae interact to enable movement of the head?

The atlas ($\text{C}_1$) supports the skull by articulating with the occipital condyles and forms a pivot joint with the odontoid process (dens) of the axis ($\text{C}_2$), enabling head rotation from side to side.

Which anatomical parts of the human rib cage are shown, and how are the ribs classified based on sternal attachment?

The sternum consists of the manubrium, body, and xiphoid process. Ribs $1$ through $7$ are true ribs attached directly via costal cartilages; ribs $8$ through $10$ are false ribs attached to the $7\text{th}$ costal cartilage; ribs $11$ and $12$ are floating ribs with no anterior sternal attachment.

What is the structural and functional difference between tendons and ligaments?

Tendons attach skeletal muscles to bones to facilitate movement, whereas ligaments connect bones to other bones across joints to stabilize the skeleton.

What are bursae, and how do they reduce friction in and around synovial joints?

Bursae are small closed sacs lined with synovial membrane and filled with synovial fluid, situated between moving bones and tendons that cross the joint to allow frictionless gliding.

Which group of short bones is illustrated in this diagram of the wrist?

The carpals, which comprise $8$ short bones (scaphoid, lunate, triquetral, pisiform, trapezium, trapezoid, capitate, and hamate) forming gliding joints that allow multidirectional hand movement.

How do the functional joint classifications synarthrosis, amphiarthrosis, and diarthrosis differ in degree of movement?

Synarthroses are immovable joints connected by fibrous connective tissue (such as cranial sutures); amphiarthroses are slightly movable joints connected by cartilage discs (such as intervertebral symphyses); diarthroses are freely movable synovial joints enclosed by a capsule and lubricated by synovial fluid.

What anatomical distinction differentiates the pubic arch of a biological female pelvis from that of a male pelvis?

The pubic arch of a female pelvis is wider, measuring greater than $90^\circ$ to accommodate childbirth, whereas a male pubic arch is narrower, measuring less than $90^\circ$.