Lab 2 - Sep 18, 2024.pdf

1 Lab 2: Part A. Classification of Tissues Part B. Integumentary System Pre-lab Checklist: (to be completed before Lab 2) o Complete the Review Sheets from Lab 1. o Be prepared for the...

1 Lab 2: Part A. Classification of Tissues Part B. Integumentary System Pre-lab Checklist: (to be completed before Lab 2) o Complete the Review Sheets from Lab 1. o Be prepared for the lab quiz at the beginning of this lab. It will be based on last week’s lab. o Read the entire Lab 2. o If you own A Brief Atlas of the Human Body, please bring it to lab so that you can use the colour plates on pp. 1 – 13. Copies will also be available for you in the lab. Learning Objectives: The student should be able to: 1. List the four basic/primary tissue types in the human body and their subcategories. 2. Describe the location, structural characteristics and functions for each tissue studied (see list). 3. Identify the tissues of each subcategory microscopically or in an appropriate image. 4. Explain how the endocrine and exocrine glands differ in structure and function. 5. List important functions of the skin or integumentary system. 6. Identify the skin structures on a model or image as listed on the model key terms (human skin models # 1 and 2). 7. Name and describe the layers of the epidermis, dermis and hypodermis. 8. Describe the distribution and function of hairs, sebaceous glands, eccrine and apocrine sweat glands. Key Terms: epithelial tissue, apical surface, basal surface, basement membrane, endothelium, avascular, squamous, cuboidal, columnar, simple, stratified, pseudostratified, transitional, endocrine gland, exocrine gland, goblet cells connective tissue, extracellular matrix (ECM), ground substance, collagen fibers, elastic fibers, reticular fibers, fibroblasts, macrophage, connective tissue proper, loose connective tissue, areolar connective tissue, adipose tissue, adipocyte, dense connective tissue, cartilage, chondrocyte, lacunae, hyaline cartilage, epiphyseal plates, elastic cartilage, fibrocartilage, osteocytes, osteon, lamellae, canaliculi, central canal / nervous tissue, neurons, glial cells (neuroglia or glia) skeletal muscle, cardiac muscle, smooth muscle, multinucleated, striation, intercalated discs  2 integumentary system, epidermis, dermis, subcutaneous tissue (hypodermis) keratinocytes, melanocytes, melanin, dendritic cells, tactile epithelial cells (Merkel cells), lamellar (Pacinian) corpuscle, tactile (Meissner’s) corpuscle, stratum basale, stratum spinosum, stratum granulosum, stratum lucidum, stratum corneum, papillary dermis, dermal papillae, reticular dermis, tactile corpuscle hair shaft, root, bulb, follicle, sweat (sudoriferous) glands, eccrine (merocrine) sweat glands, apocrine sweat glands, sebaceous (oil) glands, arrector pili muscle, sebum, acne Please see below the list of tissues you are responsible for in this lab. I. Epithelial Tissue − Simple squamous epithelium − Simple cuboidal epithelium − Simple columnar epithelium − Stratified squamous epithelium − Pseudostratified ciliated columnar epithelium − Transitional epithelium II. Connective Tissue − Areolar loose connective tissue proper − Adipose loose connective tissue proper − Dense regular connective tissue proper − Hyaline cartilage connective tissue − Fibrocartilage connective tissue − Elastic cartilage connective tissue − Compact bone connective tissue − Blood connective tissue III. Muscle Tissue − Skeletal muscle − Cardiac muscle − Smooth muscle IV. Nervous Tissue  3 Part A: Classification of Tissues Cells are the basic functional unit of life. In single-celled (unicellular) organisms, this single cell does all the necessary functions for life, but in more complex organisms, cells group together and rely on one another in order to maintain homeostasis in the body. The term tissue is used to describe a group of cells found together in the body. Cells in the same tissue share structural features and are arranged in an orderly pattern that achieves the tissue’s functions. Although there are many types of cells in the human body, they are organized into four broad categories of tissues: epithelial, connective, muscle, and nervous (Figure 2.1). Each of these tissue types is characterized by specific functions that contribute to the overall health and maintenance of the human body. Figure 2.1 The four primary tissue types are seen above: nervous tissue, (stratified squamous) epithelial tissue, (cardiac) muscle tissue, and connective tissue (in small intestine). Clockwise from nervous tissue, LM × 872, LM × 282, LM × 460, LM × 800. (Micrographs provided by the Regents of University of Michigan Medical School © 2012) Most images and text found in this section are a derivative of "Anatomy and Physiology" by OpenStax CNX used under CC BY 4.0. Aug 2, 2019. Download the original text for free at https://openstax.org/books/anatomy-and-physiology/pages/1- introduction  4 Epithelial tissue, also referred to as epithelium, refers to the sheets of cells that cover exterior surfaces of the body, lines internal cavities and passageways, and forms certain glands. Connective tissue, as its name implies, binds the cells and organs of the body together and functions in the protection, support, and integration of all parts of the body. Muscle tissue is excitable, responding to stimulation and contracting to provide movement. Nervous tissue is also excitable, allowing the propagation of electrochemical signals in the form of nerve impulses that allow communication between different regions of the body. The next level of organization is the organ, where several types of tissues come together to form a working unit. Just as knowing the structure and function of cells helps you in your study of tissues, knowledge of tissues will help you understand how organs function. Epithelial Tissue Most epithelial tissues are essentially large sheets of cells covering all the surfaces of the body exposed to the outside world and lining the outside of organs. Epithelium also forms much of the glandular tissue of the body. Skin is not the only area of the body exposed to the outside. Other areas include the airways, the digestive tract, as well as the urinary and reproductive systems, all of which are lined by an epithelium. Hollow organs and body cavities that do not connect to the exterior of the body, which includes blood vessels and serous membranes, are lined by endothelium (plural = endothelia), which is a type of epithelium. Epithelial tissue is highly cellular, with little or no extracellular material present between cells. All epithelia share some important structural and functional features that define epithelial tissue: Polarity – Epithelial cells exhibit polarity with differences in structure and function between the exposed or apical-facing surface of the cell and the basal surface close to the underlying body structures. Certain organelles are segregated to the basal sides, whereas other organelles and extensions, such as cilia, when present, are on the apical surface. Supported by connective tissue – The basement membrane, a combination of the basal and reticular laminas, connects epithelial tissues underlying connective tissues to provide structural and functional support. The epithelial layer secretes the basal lamina, a mixture of glycoproteins and collagen, which connects to a reticular lamina secreted by the underlying connective tissue. Avascular – Epithelial tissues are nearly completely avascular, meaning that they do not contain blood vessels. All materials that enter or leave the epithelial layer must come by diffusion or absorption from underlying tissues or the surface. Innervated – Most epithelial tissues are supplied by nervous tissue to allow interaction with the external environment. Regeneration – Many epithelial tissues are capable of rapidly replacing damaged and dead cells. Sloughing off of damaged or dead cells is a characteristic of surface Most images and text found in this section are a derivative of "Anatomy and Physiology" by OpenStax CNX used under CC BY 4.0. Aug 2, 2019. Download the original text for free at https://openstax.org/books/anatomy-and-physiology/pages/1- introduction  5 epithelium and allows our airways and digestive tracts to rapidly replace damaged cells with new cells. A key function for many epithelial tissues is to serve as the body’s first line of protection from physical, chemical, and biological wear and tear. The cells of an epithelium act as gatekeepers of the body controlling permeability and allowing selective transfer of materials across a physical barrier. All substances that enter the body must cross an epithelium. Some epithelia often include structural features that allow the selective transport of molecules and ions across their cell membranes. Many epithelial cells are also capable of secretion and release mucous and specific chemical compounds onto their apical surfaces. The epithelium of the small intestine releases digestive enzymes, for example. Cells lining the respiratory tract secrete mucus that traps incoming microorganisms and particles. Glandular Epithelium A gland is a structure made up of one or more cells modified to synthesize and secrete chemical substances. Most glands consist of groups of epithelial cells. A gland can be classified as an endocrine gland, a ductless gland that releases secretions directly into surrounding tissues and fluids (endo = “inside”), or an exocrine gland whose secretions leave through a duct that opens directly, or indirectly, to the external environment (exo = “outside”). Endocrine Glands The secretions of endocrine glands are called hormones. Hormones are released into the interstitial fluid, diffused into the bloodstream, and delivered to cells that have receptors to bind the hormones. The endocrine system is part of a major regulatory system coordinating the regulation and integration of body responses. A few examples of endocrine glands include the anterior pituitary, thymus, adrenal cortex, and gonads. Further information about the endocrine system will be discussed in Biology 1221. Exocrine Glands Exocrine glands release their contents through a duct that leads to the epithelial surface. Mucus, sweat, saliva, and breast milk are all examples of secretions from exocrine glands. They are all discharged through tubular ducts. Secretions into the lumen of the gastrointestinal tract, technically outside of the body, are of the exocrine category. Classification of Epithelial Tissues Epithelial tissues are classified according to the shape of the cells and number of the cell layers formed (Figure 2.2). Cell shapes can be squamous (flattened and thin), cuboidal (boxy, as wide as it is tall), or columnar (rectangular, taller than it is wide). Similarly, the number of cell layers in the tissue can be one—where every cell rests on the basal lamina—which is a simple epithelium, or more than one, which is a stratified epithelium and only the basal layer of cells rests on the basal lamina. Pseudostratified (pseudo- = “false”) describes tissue with a single layer of irregularly shaped cells that give the appearance of more than one layer. Most images and text found in this section are a derivative of "Anatomy and Physiology" by OpenStax CNX used under CC BY 4.0. Aug 2, 2019. Download the original text for free at https://openstax.org/books/anatomy-and-physiology/pages/1- introduction  6 Figure 2.2 Epithelial tissue structural types. Greyed out structures are ones you are not responsible for in lab. Simple Epithelium The shape of the cells in the single cell layer of simple epithelium reflects the function of those cells. Simple squamous epithelial cells have the appearance of thin scales. Squamous cell nuclei tend to be flat, horizontal, and elliptical, mirroring the form of the cell. Simple squamous epithelium, because of the thinness of the cell, is present where rapid passage of chemical compounds is required. The alveoli of lungs where gases diffuse, kidney glomeruli and corpuscles and segments of kidney tubules, and the lining of capillaries are also made of simple squamous epithelial tissue. In simple cuboidal epithelium, the nucleus of the box-like cells appears round and is generally located near the center of the cell. These epithelia are active in the secretion and absorption of molecules. Simple cuboidal epithelia are observed in the lining of the kidney tubules and in the ducts of glands. Most images and text found in this section are a derivative of "Anatomy and Physiology" by OpenStax CNX used under CC BY 4.0. Aug 2, 2019. Download the original text for free at https://openstax.org/books/anatomy-and-physiology/pages/1- introduction  7 In simple columnar epithelium, the nucleus of the tall column-like cells tends to be elongated and located in the basal end of the cells. Like cuboidal epithelia, this epithelium is active in the absorption and secretion of molecules. Simple columnar epithelium forms the lining of some sections of the digestive system and parts of the female reproductive tract. Ciliated columnar epithelium is composed of simple columnar epithelial cells with cilia on their apical surfaces. These epithelial cells are found in the lining of the uterine tubes and parts of the respiratory system, where the beating of the cilia helps move materials along the apical surface of the cells. Pseudostratified ciliated columnar epithelium is a type of epithelium that appears to be stratified but instead consists of a single layer of irregularly shaped and differently sized columnar cells. In pseudostratified epithelium, nuclei of neighboring cells appear at different levels rather than clustered in the basal end. The arrangement Figure 2.3 In the lining of the small intestine, columnar epithelium cells gives the appearance of are interspersed with goblet cells. The arrows in this micrograph point stratification; but in fact, all to the mucus-secreting goblet cells. LM × 1600. (Micrograph provided the cells are in contact with by the Regents of University of Michigan Medical School © 2012). the basal lamina, although some do not reach the apical surface. Pseudostratified columnar epithelium is found in the respiratory tract, where some of these cells have cilia. In addition to the epithelial cells described above, both simple and pseudostratified columnar epithelial typically include additional types of cells interspersed among the epithelial cells. For example, a goblet cell is a mucus-secreting unicellular gland interspersed between the columnar epithelial cells of mucous membranes (Figure 2.3). Stratified Epithelium A stratified epithelium consists of more than one stacked layer of cells. Stratified epithelium is typically found in places where protection against physical and chemical wear and tear is needed. Stratified epithelium is named by the shape of the most apical layer of cells, closest to the free space. Stratified squamous epithelium is the most common type of stratified Most images and text found in this section are a derivative of "Anatomy and Physiology" by OpenStax CNX used under CC BY 4.0. Aug 2, 2019. Download the original text for free at https://openstax.org/books/anatomy-and-physiology/pages/1- introduction  8 epithelium in the human body. The apical cells are squamous, whereas the basal layer contains either columnar or cuboidal cells. The top layer may be covered with dead cells filled with keratin. Mammalian skin is an example of keratinized stratified squamous epithelium while the lining of the oral cavity is an example of a nonkeratinized stratified squamous epithelium. Stratified cuboidal epithelium and stratified columnar epithelium can be found in certain glands and ducts, but are relatively uncommon in the human body. Figure 2.4 Summary of structural categories of epithelial tissues Another kind of stratified epithelium is transitional epithelium, so-called because the shape of the apical cells can undergo gradual changes in shape. Transitional epithelium is found only in the urinary system, specifically the ureters and urinary bladder. When the bladder is empty, this epithelium is folded and has cuboidal apical cells with convex, umbrella-shaped, apical surfaces. As the bladder fills with urine, this epithelium loses its folds and the apical cells transition from Most images and text found in this section are a derivative of "Anatomy and Physiology" by OpenStax CNX used under CC BY 4.0. Aug 2, 2019. Download the original text for free at https://openstax.org/books/anatomy-and-physiology/pages/1- introduction  9 cuboidal to squamous. It appears thicker and more multi-layered when the bladder is empty, and more stretched out and less stratified when the bladder is full and distended. Figure 2.4 summarizes the different structural categories of epithelial tissue types. Activity 1. Histology of Epithelium Microscope Plate # in Name of Tissue Slide A Brief Atlas of the Human Body Simple squamous epithelium #5 1, 2 Lung c.s. #4 Simple cuboidal epithelium #6 3 Simple columnar epithelium #7 4 Pseudostratified ciliated columnar #9 6 epithelium Stratified squamous epithelium #8 7 Transitional epithelium Demo -- Work together in pairs to complete this microscope activity. Refer to Lab 1 for proper handling of a microscope. shope of the cel 1. What do you see? Use the space below to draw and describe key features that will help # of layers you identify these tissues in the future. base white space , a. Shape of cells (flattened, square, etc.) b. Location of nuclei A4 c. Number of layers a # wi · M #overage 6) mmmmmmmmmmm # same 8 X Name, location , structure know function 40x , Most images and text found in this section are a derivative of "Anatomy and Physiology" by OpenStax CNX used under CC BY 4.0. Aug 2, 2019. Download the original text for free at https://openstax.org/books/anatomy-and-physiology/pages/1- introduction  10 2. What location/organ would find each type of tissue? Why might you find this tissue there? Connective Tissue As may be obvious from its name, one of the major functions of connective tissue is to support and connect tissues and organs. From the connective tissue sheath that surrounds muscle cells, to the tendons that attach muscles to bones, and to the skeleton that supports the positions of the body, support is a critical function of connective tissues. Protection is another major function of connective tissue which includes bones that protect delicate organs and, of course, the skeletal system. In addition, specialized cells in connective tissue defend the body from microorganisms that enter the body. Transport of fluid, nutrients, waste, and chemical messengers is ensured by specialized fluid connective tissues, such as blood and lymph. Finally, adipose cells store surplus energy in the form of fat and contribute to thermal insulation of the body. Unlike epithelial tissue, which is composed of cells closely packed with little or no extracellular space in between, connective tissue cells are dispersed in an extracellular matrix. The matrix usually includes a large amount of extracellular material produced by the connective tissue cells that are embedded within it and plays a major role in the function of the tissue. Connective tissues come in a vast variety of forms, yet they have three characteristic components in common: specialized cells, large amounts of ground substance, and extracellular fibers. The ground substance can vary from a watery fluid in blood, to a dense gel in cartilage, and even a mineralized matrix in bones. The amount and structure of each component correlates with the function of the tissue, from the rigid ground substance in bones supporting the body to the inclusion of specialized cells; for example, a phagocytic cell that engulfs pathogens and also rids tissue of cellular debris. The three broad categories of connective tissue are classified according to the characteristics of their ground substance and the types of fibers found within the matrix (Table 2.1) and are described further below. Table 2.1 Categories of Connective Tissue. Connective Tissue Proper Supportive Connective Tissue Fluid Connective Tissue Cartilage Loose Connective Tissue Hyaline Areolar Blood Fibrocartilage Adipose Elastic Dense Connective Tissue Bone --- Regular Most images and text found in this section are a derivative of "Anatomy and Physiology" by OpenStax CNX used under CC BY 4.0. Aug 2, 2019. Download the original text for free at https://openstax.org/books/anatomy-and-physiology/pages/1- introduction  11 Connective Tissue Proper Connective tissue proper includes loose connective tissue and dense connective tissue. Both tissues have a variety of cell types (mesenchymal cells, fibroblasts, adipocytes, macrophages, lymphocytes, and mast cells) and protein fibers (collagen, elastic, and reticular) suspended in a viscous ground substance. Dense connective tissue is reinforced by bundles of fibers that provide tensile strength, elasticity, and protection. In loose connective tissue, the fibers are loosely organized, leaving large spaces between structures. These connective tissues are considered “proper” because they show all three characteristics of connective tissue (dispersed cells in matrix, more extracellular materials than cells, extensive amounts of protein fibers) with the least amount of deviation from them. Loose Connective Tissue Loose connective tissue is found between many organs where it acts both to absorb shock and bind tissues together. It allows water, salts, and various nutrients to diffuse through to adjacent or embedded cells and tissues. Areolar loose connective tissue proper shows little specialization and is the most abundant type of connective tissue. It has a gel-like matrix and contains all the cell types and fibers previously listed and is distributed in a random, web-like fashion (Figure 2.5). It fills the spaces between muscle fibers, surrounds blood and lymph vessels, and supports organs in the abdominal cavity. Areolar tissue underlies most epithelia and represents the connective tissue component of epithelial membranes. Figure 2.5 Areolar tissue. LM × 400. (Micrograph provided by the Regents of University of Michigan Medical School © 2012) Adipose loose connective tissue proper consists mostly of fat storage cells (adipocytes), with little extracellular matrix (Figure 2.6). These adipocytes collect fat in vacuoles, which push the nucleus to the periphery of the cell. Many capillaries allow rapid storage and mobilization of lipid molecules. White adipose tissue is most abundant and appears yellow due to carotene and related pigments from plant food. White fat contributes mostly to lipid storage and can serve as insulation from cold temperatures and mechanical injuries. White adipose tissue can be found protecting the kidneys and cushioning the back of the eye, and often collects under the dermis, in the subcutaneous layer. Most images and text found in this section are a derivative of "Anatomy and Physiology" by OpenStax CNX used under CC BY 4.0. Aug 2, 2019. Download the original text for free at https://openstax.org/books/anatomy-and-physiology/pages/1- introduction  12 Figure 2.6 Adipose Tissue. LM × 800. (Micrograph provided by the Regents of University of Michigan Medical School © 2012) Dense Connective Tissue Dense connective tissue contains more collagen fibers than loose connective tissue. As a consequence, it displays greater resistance to stretching. There are two major categories of dense connective tissue: regular and irregular. Dense regular connective tissue proper contains fibroblasts and primarily has collagen fibers that run parallel to each other which enhances tensile strength and resistance to stretching in the direction of the fiber orientations (Figure 2.7). Ligaments and muscle tendons are made of dense regular connective tissue, though in ligaments not all fibers run parallel. Some dense regular tissues include elastin fibers in addition to collagen fibers, which allows the ligament to return to its original length after stretching. The ligaments in the vocal folds and between the vertebrae in the vertebral column are often classified as elastic. Figure 2.7 Dense regular connective tissue. LM × 1000 (Micrographs provided by the Regents of University of Michigan Medical School © 2012) Sources used in the writing of this section include: Marieb, E. N., & Hoehn, K. (2019). Human Anatomy & Physiology (11th ed.). Hoboken, NJ: Pearson Education, Inc. Supportive Connective Tissue Supportive connective tissue—bone and cartilage—provide structure and strength to the body and protect soft tissues. A few distinct cell types and densely packed fibers in a matrix characterize these tissues. In bone, the matrix is rigid and described as calcified because of the Most images and text found in this section are a derivative of "Anatomy and Physiology" by OpenStax CNX used under CC BY 4.0. Aug 2, 2019. Download the original text for free at https://openstax.org/books/anatomy-and-physiology/pages/1- introduction  13 deposited calcium salts. Two major forms of supportive connective tissue, cartilage and bone, allow the body to maintain its posture and protect internal organs. Cartilage Cartilage has a firm matrix, which is produced by chondroblasts. Embedded within the cartilage matrix are mature cells called chondrocytes, and the space they occupy are called lacunae -verting (singular = lacuna). A layer of dense irregular connective tissue, the perichondrium, encapsulates the cartilage. Cartilaginous tissue is avascular; thus, all nutrients need to diffuse through the matrix to reach the chondrocytes. This is a factor contributing to the very slow healing of cartilaginous tissues. The three main types of cartilage tissue are hyaline cartilage, fibrocartilage, and elastic cartilage. Hyaline cartilage, the most common type of cartilage in the body, provides support with some flexibility. The cartilage matrix consists of short and dispersed collagen fibers. Under the microscope, tissue samples appear clear (Figure 2.8). The surface of hyaline cartilage is smooth. Both strong and flexible, it is found in the rib cage and nose and covers bones where they meet to form moveable joints. It makes up a template of the embryonic skeleton before bone formation, as well as the epiphyseal plate – the area of growth in a long bone. Figure 2.8 Hyaline cartilage. LM × 300. (Micrographs provided by the Regents of University of Michigan Medical School © 2012) Fibrocartilage provides some compressibility and can absorb pressure. Fibrocartilage is tough because it has thick bundles of collagen fibers dispersed through its matrix (Figure 2.9). Menisci in the knee joint, the pubic symphysis, and the intervertebral discs are examples of fibrocartilage. Most images and text found in this section are a derivative of "Anatomy and Physiology" by OpenStax CNX used under CC BY 4.0. Aug 2, 2019. Download the original text for free at https://openstax.org/books/anatomy-and-physiology/pages/1- introduction  14 Figure 2.9 Fibrocartilage. LM × 1200 (Micrographs provided by the Regents of University of Michigan Medical School © 2012) Elastic cartilage provides firm but elastic support. Elastic cartilage contains elastic fibers as well as collagen (Figure 2.10). Tug gently at your ear lobes, and notice that the lobes return to their initial shape. Like the external ear, the epiglottis also contains elastic cartilage. Figure 2.10 Elastic cartilage. LM × 1016 (Micrographs provided by the Regents of University of Michigan Medical School © 2012) Most images and text found in this section are a derivative of "Anatomy and Physiology" by OpenStax CNX used under CC BY 4.0. Aug 2, 2019. Download the original text for free at https://openstax.org/books/anatomy-and-physiology/pages/1- introduction  15 Bone Bone is the hardest connective tissue, and can be separated into compact (the denser, stronger type) and spongy (the lighter, supportive type) bone. It provides protection to internal organs, supports the body, stores calcium, and provides scaffolding and lever systems for muscles to allow movement. Bone’s rigid extracellular matrix contains mostly collagen fibers covered in a mineralized ground substance containing hydroxyapatite, a form of calcium phosphate. Both components of the matrix, organic and inorganic, contribute to the unusual properties of bone. Without collagen, bones would be brittle and shatter easily. Without mineral crystals, bones would flex and provide little support. Osteocytes (mature bone cells), like chondrocytes, are located within lacunae. (Figure 2.11) Bone is a highly vascularized tissue and, unlike cartilage, bone tissue can recover from injuries in a relatively short time. The structure of bone will be considered further in Lab 3. Figure 2.11 Compact bone. LM × 40. (Micrograph provided by the Regents of University of Michigan Medical School © 2012) Fluid Connective Tissue Lymph and blood are the fluid connective tissues. They contain various specialized cells circulating in a watery extracellular matrix containing salts, nutrients, and dissolved proteins. Blood contains the formed elements (erythrocytes, leukocytes, and platelets) that contribute to the transportation of materials, such as respiratory gases, throughout the body and our body’s ability to respond to injury and illness (Figure 2.12). Lymph contains a liquid matrix and leukocytes. Lymph eventually drains into blood vessels, delivering molecules to the blood that could not otherwise directly enter the bloodstream, which includes absorbed fats transported away from the intestine. Most images and text found in this section are a derivative of "Anatomy and Physiology" by OpenStax CNX used under CC BY 4.0. Aug 2, 2019. Download the original text for free at https://openstax.org/books/anatomy-and-physiology/pages/1- introduction  16 Leukocyte Platelet Figure 2.12 Blood: A Fluid Connective Tissue. LM × 1600. (Micrograph provided by the Regents of University of Michigan Medical School © 2012) Most images and text found in this section are a derivative of "Anatomy and Physiology" by OpenStax CNX used under CC BY 4.0. Aug 2, 2019. Download the original text for free at https://openstax.org/books/anatomy-and-physiology/pages/1- introduction  Substance Brown - State of tre 17 - Fibre name of _ Activity 2. Histology of Connective Tissue Microscope Plate # in Name of Tissue Slide A Brief Atlas of the Human Body Areolar loose connective tissue proper #10 11 Adipose loose connective tissue proper #11 12 Dense regular connective tissue proper #12 15 Hyaline cartilage, connective tissue #13 17 Fibrocartilage, connective tissue #15 19 Elastic cartilage, connective tissue #14 18 Compact bone, connective tissue #16 20 Blood, connective tissue #17 22 Work together in pairs to complete this microscope activity. Refer to Lab 1 for proper handling of a microscope. 1. What do you see? Use the space below to draw and describe key features that will help you identify these tissues in the future. a. Ground substance b. Types of fibers far es psquiries c. Cell types l #) lar - Most images and text found in this section are a derivative of "Anatomy and Physiology" by OpenStax CNX used under CC BY 4.0. Aug 2, 2019. Download the original text for free at https://openstax.org/books/anatomy-and-physiology/pages/1- introduction  18 2. What location/organ would find each type of tissue? Why might you find this tissue here? Muscle Tissue Muscle tissue is characterized by properties that allow movement. Muscle cells are excitable, which means they can respond to a stimulus. They are also contractile, meaning they can shorten and generate a force. When attached between two movable objects (bones) muscle contractions cause the bones to move. Some muscle movements are voluntary (under conscious control). For example, when a person uses their arm to open a book and read a chapter on anatomy. Other movements are involuntary, such as the change in the diameter of your pupil in response to bright light. Muscle tissue is classified into three types according to structure and function: skeletal, cardiac, and smooth (Table 2.2 and Figure 2.13). Table 2.2 Muscle Tissue Types. Tissue Cell Structure Major Function Location Attached to bones Long cylindrical fiber, Voluntary movement, produces and around Skeletal striated, many peripherally heat, protects organs entrance points to located nuclei body Short, branched, striated, Cardiac Contracts to move blood in the heart Heart single central nucleus Involuntary movement of many Walls of major Short, spindle-shaped, materials including food, air during Smooth organs and single nucleus in each fiber respiration, secretions, and the flow passageways of blood through blood vessels Most images and text found in this section are a derivative of "Anatomy and Physiology" by OpenStax CNX used under CC BY 4.0. Aug 2, 2019. Download the original text for free at https://openstax.org/books/anatomy-and-physiology/pages/1- introduction  19 Figure 2.13 Muscle Tissue (a) Skeletal muscle (b) Smooth muscle (c) Cardiac muscle. All images are LM × 1600. (Micrographs provided by the Regents of University of Michigan Medical School © 2012) Most images and text found in this section are a derivative of "Anatomy and Physiology" by OpenStax CNX used under CC BY 4.0. Aug 2, 2019. Download the original text for free at https://openstax.org/books/anatomy-and-physiology/pages/1- introduction  20 Skeletal muscle tissue is attached to bones and its contraction makes voluntary movements of the body possible, including locomotion, facial expressions, and posture. Forty percent of your body mass is made up of skeletal muscle. Another function of skeletal muscle is to generate heat as a byproduct of their contraction and thus participate in thermal homeostasis. Under a light microscope, muscle cells appear striated with many nuclei squeezed along the membranes. The striation is due to the regular alternation of the contractile proteins, actin and myosin, along with the structural proteins that couple the contractile proteins to connective tissues. The cells are multinucleated as a result of the fusion of the many myoblasts that fuse to form each long muscle fiber. The gross anatomy of skeletal muscle is considered further in Lab 5. Cardiac muscle tissue forms the contractile walls of the heart. The cardiac muscles cells also appear striated under the microscope. Unlike skeletal muscle fibers, cardiomyocytes are single, branched cells typically with a single centrally located nucleus. Cardiomyocytes attach to one another with specialized cell junctions called intercalated discs. Smooth muscle tissue contraction is responsible for involuntary movements in the internal organs. It forms the contractile component of the digestive, urinary, and reproductive systems as well as the airways and arteries. Each cell is small, spindle-shaped and has a single nucleus with no visible striations. Activity 3. Histology of Muscle Tissue Microscope Slide Plate # in Name of Tissue A Brief Atlas of the Human Body Skeletal muscle tissue #18 28 Cardiac muscle tissue #19 31 Smooth muscle tissue #20, 21 32 Work together in pairs to complete this microscope activity. Refer to Lab 1 for proper handling of a microscope. 1. What do you see? Use the space below to draw and describe key features that will help you identify these tissues in the future. a. Striations b. Number of nuclei c. Cell shape Most images and text found in this section are a derivative of "Anatomy and Physiology" by OpenStax CNX used under CC BY 4.0. Aug 2, 2019. Download the original text for free at https://openstax.org/books/anatomy-and-physiology/pages/1- introduction  21 2. What location/organ would find this type of tissue? Why might you find this tissue here? Nervous Tissue Nervous tissue contains two basic types of cells: neurons and glial cells. Neurons are the primary type of cell that most anyone associates with the nervous system (Figure 2.14). They are responsible for the computation and communication that the nervous system provides. They are electrically active and release chemical signals to target cells. Glial cells, or glia, are known to play a supporting role for nervous tissue. Ongoing research pursues an expanded role that glial cells might play in signaling, but neurons are still considered the basis of this function. Neurons are important, but without glial support they would not be able to perform their function. More details about the anatomy of neurons will be covered in Lab 7. Figure 2.14 Neuron anatomy for a generic multipolar neuron from the CNS. Close up of a giant multipolar neuron in the spinal cord. LM × 800. (Micrograph provided by the Regents of University of Michigan Medical School © 2012) Most images and text found in this section are a derivative of "Anatomy and Physiology" by OpenStax CNX used under CC BY 4.0. Aug 2, 2019. Download the original text for free at https://openstax.org/books/anatomy-and-physiology/pages/1- introduction  22 Activity 4. Histology of Nervous Tissue Microscope Slide Plate # in Name of Tissue A Brief Atlas of the Human Body Giant multipolar neuron #22 33 Work together in pairs to complete this microscope activity. Refer to Lab 1 for proper handling of a microscope. 1. What do you see? Use the space below to draw and describe key features that will help you identify this tissue in the future. 2. What location/organ would find this type of tissue? Why might you find this tissue here? Most images and text found in this section are a derivative of "Anatomy and Physiology" by OpenStax CNX used under CC BY 4.0. Aug 2, 2019. Download the original text for free at https://openstax.org/books/anatomy-and-physiology/pages/1- introduction  23 Part B: The Integumentary System The integumentary system refers to the skin and its accessory structures and is responsible for much more than simply lending to your outward appearance. In the adult human body, the skin makes up about 15 percent of body weight and covers an area of 1.2 to 2.2 m2. In fact, the skin and accessory structures are the largest organ system in the human body. Although you may not typically think of the skin as an organ, it includes each of the four primary tissue types that work together as a single structure to perform unique and critical functions, which includes physical protection, thermoregulation, serving as a major sensory organ, playing a key role in your immune systems, and is a major site of lipid storage. The skin is composed of two main layers: the epidermis, and the dermis which includes blood vessels, hair follicles, sweat glands, and other structures. Beneath the dermis lies the subcutaneous tissue (hypodermis), which is composed mainly of loose connective and fatty tissues. The skin is held to underlying muscles and other structures by connective tissue (Figure 2.15). The deeper layer of skin is well vascularized (has numerous blood vessels) and has numerous sensory structures and nerve fibers to allow communication to and from the brain. Figure 2.15 The Integumentary System. From: Hoehn, K., Hayes, L., & Abbott, M. (2025). Human Anatomy & Physiology (12th ed). Hoboken, NJ: Pearson Education, Inc. Most images and text found in this section are a derivative of "Anatomy and Physiology" by OpenStax CNX used under CC BY 4.0. Aug 2, 2019. Download the original text for free at https://openstax.org/books/anatomy-and-physiology/pages/1- introduction  24 The Epidermis The epidermis is composed of keratinized, stratified squamous epithelium. It is made of four or five epithelial layers, depending on its location in the body. Like other epithelial tissues it does not have any blood vessels within it and is avascular. Thick skin has five distinct layers of cells in the epidermis and is only found on the palms of the hands and the soles of the feet. Thin skin is found everywhere else on the body and has only four layers. From deep to superficial, these layers are the stratum basale, stratum spinosum, stratum granulosum, stratum lucidum, and stratum corneum (Figure 2.16). The stratum lucidum is the layer only found in thick skin. Major features of each layer are summarized in Table 2.3. only S in found skin. thick stratum basal except Figure 2.16 The Epidermis. Cells of the Epidermis Keratinocytes are the dominant cell type in all the layers except the stratum basale. Keratinocytes manufacture, modify, and store the protein keratin which is an intracellular fibrous protein that gives hair, nails, and skin their hardness and water-resistant properties. Melanocytes are cells that produce the pigment melanin. Melanin gives hair and skin its color, and helps protect the living cells of the epidermis from ultraviolet (UV) radiation damage. Melanin concentrated in a small area is called a freckle. Most images and text found in this section are a derivative of "Anatomy and Physiology" by OpenStax CNX used under CC BY 4.0. Aug 2, 2019. Download the original text for free at https://openstax.org/books/anatomy-and-physiology/pages/1- introduction  know layers know cells 25 Dendritic cells (Langerhans cells) can be found in the stratum spinosum, which function as macrophages by engulfing bacteria, foreign particles, and damaged cells that occur in this layer. Tactile epithelial cells (Merkel cells) are found dispersed among the basal cells in the stratum basale (Figure 2.16). These cells function as receptors and are responsible for stimulating sensory nerves that the brain perceives as touch. These cells are especially abundant on the surfaces of the hands and feet. On a Table 2.3 Epidermal Layers, listed deep to superficial. Epidermal Layer Major Features model Contains a single layer of cuboidal stem cells that give rise to keratinocytes, Stratum basale E tactile cells for touch sensation, and melanocytes for pigment production. ↑ bottom base level Several layers of keratinocytes that contain thick bundles of intermediate Stratum spinosum A demteric cells , present filaments; dendritic cells are found here. 1-5 layers of keratinocytes. Process of keratinization begins – cells flatten, Stratum granulosum their nuclei and organelles begin to disintegrate. Proteins and lipids & cell sterst look to deposited outside make these cells touch and water resistant. 2 Stratum lucidum this in Thin layer of dead keratinocytes found only in thick skin. 20-30 layers of dead, keratinized keratinocytes bound together in sheets. I Stratum corneum thick This layer is shed regularly Skin Sources used in the writing of this section include: Marieb, E. N., & Hoehn, K. (2019). Human Anatomy & Physiology (11th ed.). Hoboken, NJ: Pearson Education, Inc. some been-thin layer > come - get The Dermis The underlying dermis contains blood and lymph vessels, nerves, and other accessory structures, such as hair follicles and sweat glands. The dermis is made of two layers of connective tissue that compose an interconnected mesh of elastin and collagenous fibers which are produced by fibroblasts (Figure 2.17). The papillary dermis is made of loose, areolar connective tissue. This superficial layer of the dermis projects into the stratum basale of the epidermis to form finger-like dermal papillae (see Figure 2.17). Within the papillary layer are fibroblasts, a small number of fat cells (adipocytes), and an abundance of small blood vessels. In addition, the papillary layer contains phagocytes, defensive cells that help fight bacteria or other infections that have breached the skin. This layer also contains lymphatic capillaries, nerve fibers, and touch receptors called the tactile corpuscle (Meissner’s corpuscle). Tactile corpuscles function similarly to the tactile epithelial cells found in the epidermis. Lamellar (Pacinian) corpuscles are mechanoreceptors located within the dermis (and subcutaneous tissue) that respond to deep pressure or vibration (Figure 2.15). root in the fissue, hair living part of Most images and text found in this section are a derivative of "Anatomy and Physiology" by OpenStax CNX used under CC BY 4.0. Aug 2, 2019. Download the original text for free at https://openstax.org/books/anatomy-and-physiology/pages/1- introduction  26 Underlying the papillary layer is the much thicker reticular dermis, composed of dense irregular connective tissue. This layer is well vascularized and has a rich nerve supply. The reticular dermis appears net-like due to a tight meshwork of fibers. Elastin fibers provide some elasticity to the skin, enabling movement. Collagen fibers provide structure and tensile strength, with strands of collagen extending into both the papillary dermis and the subcutaneous tissue. Sources used in the writing of this section include: Marieb, E. N., & Hoehn, K. (2019). Human Anatomy & Physiology (11th ed.). Hoboken, NJ: Pearson Education, Inc. & The Subcutaneous Tissue The subcutaneous tissue (also giands called hypodermis or superficial fascia) is a layer directly below the dermis and serves to connect the Figure 2.17 Layers of the dermis. skin to the underlying fascia of the bones and muscles. It is not strictly a part of the skin, although the border between the subcutaneous tissue and dermis can be difficult to distinguish. The subcutaneous tissue consists of well-vascularized, loose, areolar connective tissue and adipose tissue, which functions as a mode of fat storage and provides insulation and cushioning for the integument. Bedsores Skin and its underlying tissue can be affected by excessive pressure. One example of this is called a bedsore (decubitus ulcer). Bedsores are caused by constant, long-term, unrelieved pressure on certain body parts that are bony, reducing blood flow to the area and leading to necrosis (tissue death). Bedsores are most common in elderly patients who have debilitating conditions that cause them to be immobile. Most hospitals and long-term care facilities have the practice of turning the patients every few hours to prevent the incidence of bedsores. If left untreated by removal of necrotized tissue, bedsores can be fatal if they become infected. Most images and text found in this section are a derivative of "Anatomy and Physiology" by OpenStax CNX used under CC BY 4.0. Aug 2, 2019. Download the original text for free at https://openstax.org/books/anatomy-and-physiology/pages/1- introduction  27 Activity 5. Histology of Skin Microscope Slide Plate # in Name of Tissue A Brief Atlas of the Human Body Pigmented skin #23 --- Unpigmented skin #23 Work together in pairs to complete this microscope activity. Refer to Lab 1 for proper handling of a microscope. 1. What are the two types of tissues present here? Melanin In unpigmented Skin Melanocytes ↳ Epidermis outermost layer of cell Contains Melanocytes produce figment. ,. , little to no melanin lack of colour but produce ,. may be present follides is dermis. Structural support houses blood vessels , nerves , hair , glands. epidermis , ↳ Connective , beneath apperance. cells can affect skin's distribution of Melanin Surrounded Dermis is same in both Pigmented and non-p. Though 2. What are the differences between these two tissues? - Epidermis tissue Composed of > - Keratinized Strengthens Skim stratified squamous e Not part of theskincutaneous : Connective t Found in Dermis. ,. - Doesn't have any blood vessels in its avascular. > -. Dermis found beneath epidermis hypodermis Outermost layer become > - made up of fibroblasts collagen fibers , elastin fibers , extracellular matrix (Keratinocytes) , of Cells composed of Multiple layers the sur face toward ↳ Has layers move two flattened they more as. colour just epidermis (pigment producing) langherhaus cells t below Contains Melanocytes dermis thin loose C Papillary. · :. , , Cimmure Cells) Merkel cells(sensory cells) Skin deeper in , Reticular dermis · : thicker denser C +.. , protective barrier agains pathogen UV Radiation · , hair · prevent water-loss from the body · Rich in blood vessels , nerves , glands , > supports - , nourishes , provides flexibility 3. What epidermal layer are these differences observable? Stratum lucidum Epidermis , layers are : Stratum basale , stratum spirosum , Stratum Granulosum , ↳ only found in thick s Stratum. Corneum down. Reticular dermis , deeper be most clearly. Papillary Areolar C can seen Dermis dermis t - : Ct. where functional boundary between epidermal layer and underlying. is : Stratum basale Accessory Structures of the Integument Hair Hair is a keratinous filament growing out of the epidermis primarily made of dead, keratinized cells. Strands of hair originate in an epidermal penetration of the dermis called a hair follicle. The hair shaft is the part of the hair not anchored to the follicle, and much of this is exposed at the skin’s surface. The rest of the hair, which is anchored in the follicle, lies below the surface of the skin, and is referred to as the hair root. The hair root ends deep in the dermis at the hair bulb and includes a layer of mitotically active basal cells called the hair matrix which continually divide in order to produce the new cells of a growing hair. The hair bulb surrounds the hair papilla, which is made of connective tissue and contains blood capillaries and nerve endings from the dermis (Figure 2.18). Most images and text found in this section are a derivative of "Anatomy and Physiology" by OpenStax CNX used under CC BY 4.0. Aug 2, 2019. Download the original text for free at https://openstax.org/books/anatomy-and-physiology/pages/1- introduction  28 Hair serves a variety of functions, including protection, sensory input, thermoregulation, and communication. The hair in the nose and ears, and around the eyes (eyelashes) defends the body by trapping and excluding dust particles that may contain allergens and microbes. Hair of the eyebrows prevents sweat and other particles from dripping into and bothering the eyes. Hair also has a sensory function due to sensory innervation by a hair root plexus surrounding the base of each hair follicle. Hair is extremely sensitive to air movement or other disturbances in the environment, much more so than the skin surface. This feature is also useful for the detection of the presence of insects or other potentially damaging substances Figure 2.18 The structure of a hair and a hair follicle. on the skin surface. Each hair root is connected to a smooth muscle called the arrector pili muscle that contracts in response to nerve signals from the sympathetic nervous system, making the external hair shaft “stand up.” The primary purpose for this is to trap a layer of air to add insulation. This is visible in humans as goose bumps and even more obvious in other animals, such as when a frightened cat raises its fur. Cutaneous Glands Sebaceous (Oil) Gland A sebaceous gland is a type of oil gland that is found all over the body and helps to lubricate and waterproof the skin and hair. Most sebaceous glands are associated with hair follicles. They generate and excrete sebum, a mixture of lipids and cellular debris, onto the skin surface, thereby naturally lubricating the dry and dead layer of keratinized cells of the stratum corneum, keeping it pliable. The fatty acids of sebum also have antibacterial properties and prevent water loss from the skin in low-humidity environments. The secretion of sebum is stimulated by hormones, many of which do not become active until puberty. Thus, sebaceous glands are relatively inactive during childhood. Most images and text found in this section are a derivative of "Anatomy and Physiology" by OpenStax CNX used under CC BY 4.0. Aug 2, 2019. Download the original text for free at https://openstax.org/books/anatomy-and-physiology/pages/1- introduction  29 Acne is a skin disturbance that typically occurs on areas of the skin that are rich in sebaceous glands (face and back). An overproduction and accumulation of sebum along with keratin can block hair follicles. This plug is initially white. The sebum, when oxidized by exposure to air, turns black. Sudoriferous (Sweat) Glands When the body becomes warm, sudoriferous glands produce sweat to cool the body. There are two types of sweat glands, eccrine and apocrine, each secreting slightly different products. Eccrine sweat glands (also called merocrine sweat glands) produce a hypotonic sweat for thermoregulation. These glands are found all over the skin’s surface but are especially abundant on the palms of the hand, the soles of the feet, and the forehead. They are coiled glands lying deep in the dermis, with the duct rising up to a pore on the skin surface, where the sweat is released (Figure. 2.15). This type of sweat is composed mostly of water, with some salt, antibodies, traces of metabolic waste, and antimicrobial peptides. Eccrine glands are a primary component of thermoregulation in humans and thus help to maintain homeostasis. Apocrine sweat glands are usually associated with hair follicles in densely hairy areas, such as armpits and genital regions. Apocrine sweat glands are larger than eccrine sweat glands and lie deeper in the dermis, sometimes even reaching the hypodermis, with the duct normally emptying into the hair follicle. In addition to water and salts, apocrine sweat includes organic compounds that make the sweat thicker and subject to bacterial decomposition and subsequent smell. Activity 6. Plotting the Distribution of Sweat Glands Sweat glands are found in the skin and distributed across much of the body. In this activity two small areas of the body will be highlighted (forearm and palm), for sweat gland activity. Predict how those two areas would compare in the amount sweat produced. Work together in pairs to complete the following: the the more palm of > isible than - hand 1. Mark the area to be tested: the medial aspect of the forearm, and the middle of the palm of the subject’s non-dominant hand. 2. Apply Lugol’s iodine to both locations and allow to dry completely. 3. Once completely dry place a small paper square, approximately 1cm x 1cm over the painted area. Tape the paper directly onto the skin to hold it in place for 20 minutes. 4. After 20 minutes has elapsed pull the paper off each location and compare. 5. Wash your hands thoroughly with soap and water. When sweat is produced in these areas it will allow the iodine to have contact with the paper. When the iodine encounters the starch in the paper it will turn a blue-black color indicating a positive test for sweat. If the paper stays white that is a negative test for sweat. The amount of the blue-black color is relative to the number of active sweat glands in the tested areas. Most images and text found in this section are a derivative of "Anatomy and Physiology" by OpenStax CNX used under CC BY 4.0. Aug 2, 2019. Download the original text for free at https://openstax.org/books/anatomy-and-physiology/pages/1- introduction  30 a. Did the paper squares look the same after twenty minutes? look the same No squared papers did the not. b. Which location showed a positive test for sweat? Both palm of the hand and forearm were tested positive forSweat. ↳ more ! c. What can be concluded about the density of sweat glands between the two sampled locations? (eccrine sweat glands Palm the · has higher density of feet contains hand Concentration high a sweat glands , or of specifically) Eccrive present # is reduced. · Forearm has a lower density sweat glands Compared to palms. sweat glands are , d. What prediction could be made if the locations were changed to forehead and thigh, or the bottom of the foot and the shin area? l owe r as it and function is higher density would have help with Shin area of the foot grip a Bottom. , , · mainly temperature regulation. for down the body. help cool begins sweating quickly that to One o f the areas of body Forehead is higher thermoregulation. , · is lower active a s like forehead or palm. Doesn't need as much sweat production as its not Thigh density not , as , exposed/sensitive to in temp. changes Sources used in the writing of this activity include: Marieb, et al. (2014). Human Anatomy & Physiology Laboratory Manual (10th ed.). Glenview, IL: Pearson Education, Inc. Activity 7. Observing a Hair Follicle Plate # in Name of Tissue Microscope Slide A Brief Atlas of the Human Body Scalp #23 --- Work together in pairs to complete this microscope activity. Refer to Lab 1 for proper handling of a microscope. 1. What features can you see on the slide that is also observable on the skin model (see Activity 8)? I can see the external Root sheath membrane , Hair bulb , inner root sheath. , glassy Most images and text found in this section are a derivative of "Anatomy and Physiology" by OpenStax CNX used under CC BY 4.0. Aug 2, 2019. Download the original text for free at https://openstax.org/books/anatomy-and-physiology/pages/1- introduction  31 Activity 8. Labelling Human Skin Models Using the BIOL 1220 Virtual Lab Models website and other materials available to you, label the following models with the features given below: Figure 2.19 Model of Section of Skin by SOMSO. I. epidermis 8. hair shaft (longitudinal section) 1. stratum corneum 9. hair (diagonal section) 2. stratum basale 10. hair shaft 11. hair root II. dermis 11a. hair bulb 3. dermal papilla 13 sebaceous gland 7. sweat (sudoriferous) gland (eccrine 14. arrector pili muscle or merocrine gland) III. subcutaneous layer (hypodermis) Identify the three regions (A, B, and C below) of the model: A. Hairy scalp Note the abundance of hair follicles. B. Arm pit Note the presence of hair follicles and a large representative apocrine sweat gland. C. Sole of the foot Note the thickness of the epidermis and the presence of the stratum lucidum. Something is missing from the skin in region C that was present in the other two regions of the model. What is it? What is different about the sweat glands in region B, compared to sweat glands that are more widely distributed over the surface of the body? (armpits groin) primarily apocrine glands They Sweat in B glands are are thicker can stink ,.. , Whereas produce sweat for eccrime glands watery cooling.  32 Figure 2.20 Model of Human Skin Series with Burn Pathologies by Denoyer-Geppert Science Company. Look at the Burn Classifications on the reverse side, for your own interest (not pictured) Layers of the Skin Glands I Epidermis h. eccrine sweat gland a. stratum corneum (much thicker on i. eccrine sweat gland (sectioned) the sole of the foot or palm) j. duct to skin surface b. stratum lucidum (present only in k. sweat gland pore thick skin) l. apocrine sweat gland (begins to c. stratum granulosum function at puberty) d. stratum spinosum m. apocrine sweat gland (sectioned) e. stratum basale n. sebaceous gland z. portion of fingerprint o. sebaceous gland (sectioned) II Dermis Nervous Tissue f. dermal papillae u, v, w touch and pressure receptors III Hypodermis Hair g. adipose tissue A. hair follicle B. hair bulb J. hair shaft x. arrector pili muscle Post-Lab Assignment Post-Lab Assignments are due 24 hours after you leave the lab. These are found on your D2L site. You are free to work together with your peers, however you must complete and submit the assignment individually. You have unlimited attempts within the 24 hours. Submissions after this 24-hour period will not be accepted.  33 Review Sheets 1. Visit the links listed below to view various tissues. These tissues are also found in your microscope slide boxes. In the circles below, draw your observations. Take careful consideration of the size and shape of cells so you can make direct comparisons. Plate # in Name of Tissue Microscope Slides A Brief Atlas of the Human Body Simple Squamous Epithelium #5 1 and 2 Sperm Cells #36