Nutrition, Tissue and skin lab Biological & Biomedical Lab Report

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Pre-Lab Questions
What is tissue?
A tissue refers to a group of cells that are in close proximity and organized perform one or more specific functions.
What is the function of epithelial tissue?
They cover all body surfaces, line body cavities, and constitute significant tissue in glands. They perform various functions that include protection, secretion, absorption, excretion, filtration, diffusion, and sensory reception. These functions are achieved by creating protective boundaries, which allows the movement of ions and molecules.
What is the function of connective tissue?
The core functions of connective tissue include binding and supporting, protecting, insulating, storing reserve fuel, and transporting substances within the body.

What is the function of muscular tissue?
The muscle tissues have many functions, including movement, maintenance of posture, pumping blood, communication, constriction organs and blood vessels, respiration and heat generation.

What is the function of nervous tissue?
Nervous tissue is responsible for coordinating and controlling various body activities and processes. It stimulates muscle contraction, nurtures awareness of the environment, and plays a role in emotions, memory, and reasoning.

Describe sebaceous glands, sudoriferous glands, and hairs with regard to skin function.
Sebaceous glands are holocrine glands found in the skin except in the palms of the hands and soles of the feet. They produce sebum, which is an oily substance composed of fat and the debris of dead fat-producing cells. Sebum is a lubricant that helps to moisturize the skin by preventing the excessive evaporation of water from the skin. It also keeps the skin healthy by controlling the growth of bacteria on the skin. It does this by producing chemicals that are bactericidal. Finally, it conditions the hair to avoid being too try or brittle.
Sudoriferous glands, also called sweat glands, are either of two types of secretory skin glands, eccrine or apocrine. Eccrine and apocrine glands are confined within the dermis and consist of secretory cells and a central lumen into which material is secreted. The eccrine and apocrine glands release in a merocrine way such that substances are released by exocytosis without damage or loss of the secreting cell. Eccrine sweat glands permit temperature control. When body temperature rises during physical activity, or due to increased temperature or fever, these glands respond by secreting sweat. This sweat will evaporate from the surface of the skin, leading to cooling down body temperature.
What is the function of melanin?
Melanin is a natural skin pigment that determines hair, skin, and eye color in people and animals. Melanocytes produce such color pigments. The intensity of such color depends on the type and amount of melanin they have. The various forms of melanin fulfill biological functions, including skin and hair pigmentation and photoprotection of the skin and eye. The skin pigmentation is due to the accumulation of melanin-containing melanosomes in the basal layer of the epidermis.

List the similarities and differences among the layers of the epidermis.
Stratum basale is the deepest layer next to the dermis or lamina. It is attached to the basement membrane by hemidesmosomes. It has cuboidal to columnar stem cells that produce keratinocytes.
Stratum spinosum is comprised of 8-10 cell layers ( prickle cell layer), which contain irregular, polyhedral cells with cytoplasmic processes also called “spines,” that extend outward and connect with neighboring cells by desmosomes. This layer may have D\dendritic cells.
Stratum granulosum is made up of 3-5 cell layers that have diamond-shaped cells with keratohyalin granules and lamellar granules.
Stratum lucidum has 2-3 cell layers is thicker skin found in the palms and soles.
The stratum corneum has 20-30 cell layers and forms the uppermost layer made up of keratin and horny scales constituted by dead keratinocytes.
Experiment 1: Microscopic Slide Examination of Tissue
Tissue Identification
Epithelial Tissue
A) Epithelial Tissue Type ___simpler columnar_________________
B) Epithelial Tissue Type _Cuboidal epithelium_________________
Connective Tissue
C) Connective Tissue Type ______Adipose tissue ______________
D) Connective Tissue Type ____Hyaline________________
E) Connective Tissue Type ___Proper_________________
Muscular Tissue
F) Muscular Tissue Type ____skeleton muscle________________
G) Muscular Tissue Type ____smooth muscle tissue________________
Additional Tissue Type
H) Unidentified Tissue Type _loose connective tissue___________________
Post-Lab Questions
What structural characteristics did you observe for each type of tissue? Be specific.
Epithelial tissues are tightly packed and form a continuous sheet with little or no intercellular spaces.

Describe the cell shape of squamous, cuboidal, and columnar epithelial cells.
Squamous cells tend to have horizontally flattened, nearly oval-shaped nuclei because of the thin, flattened form of the cell.
Cuboidal epithelial cells have a cube-like shape. They appear square in cross-section. The cell nucleus is large, spherical, and is in the center of the cell.
Columnar epithelial cells are usually taller than they are wide. They look like a stack of columns in an epithelial layer and are often found in a single-layer arrangement.

Does the number of cell layers or the cell shape play a role in the function of epithelial tissue? Provide three examples.
Yes, it does. The layers form membranous tissues that cover both internal and external organs. They are in layers to provide strength, protection, and to allow selective movement of products.

List and describe the different types of connective tissue. What similarities and differences did you notice when viewing the slides?
Dense connective tissues, also called dense fibrous tissue, are connective tissue with fibers as its main matrix element. They form strong, rope-like structures such as tendons and ligaments.
Loose connective tissues are also called areolar connective tissue. Loose connective tissue may have fibroblasts and macrophages. They have collagen fibers loosely scattered in the ECM.
Reticular connective tissue has reticulocytes and reticular fibers that are organized in networks.
The cartilage connective tissue is made up of chondrocytes, and its extracellular matrix has different types of collagen type 2.
Osteocytes, osteoclast, and osteoblast mark the bone connective tissues, and its extracellular matrix has calcified lamellae.
Blood is another connective tissue with an extracellular matrix as blood plasma, and its cells include platelets, erythrocyte, and others.
Adipose tissue has white and brown adipocytes but has no extracellular matrix.
The embryonic connective tissue has mesenchyme cells and mucoid tissue, with a rich network of reticular fibers in the extracellular matrix.
When viewing the slides, one can notice the difference in terms of the extracellular matrix and collagen fibers density.

What are the three components of the extracellular matrix in connective tissue?
It has highly viscous proteoglycans, including heparan sulfate, keratan sulfate, chondroitin sulfate, which functions to cushion cells.
It has Insoluble collagen fibers, which provide strength and resilience
It has soluble multi-adhesive extracellular matrix proteins, for instance, fibronectin and laminin, which bind proteoglycans and collagen fibers to receptors on the cell surface

What are the three types of cartilage? What are their similarities and differences?
Hyaline cartilage is predominantly made up of cartilage and is the most common. It is found in articular surfaces of long bones, trachea, rib tips, and skull parts.
Fibrocartilage has many collagen fibers Type 1 and 2.They are mainly found in knee menisci, temporomandibular joints, and pubic symphysis, to mention a few.
Elastic cartilage has elastic fibers made of elastin and chondrocytes lying between the fibers.
What are the three types of muscular tissue? For each, describe the cell shape, the type of control (voluntary or involuntary), and the presence or absence of striations.
Cardiac muscle is a striated muscle present only in the heart. It has cardiac muscle fibers that have a single nucleus, are branched, and joined to one another by intercalated discs.
Smooth muscle is involuntarily controlled, not striated, not branched, and has a single nuclear.
Skeleton muscle is voluntary, striated, not branched, and multinucleated. 
Looking at the nervous tissue slides, list the visible cell processes (e.g., axons). For each process, state its function.
Axon facilitates electric signal conduction. Myelin helps axons to conduct an electrical signal. Neurons have one central axon.
Dendrites receive and process signals from the axons of other neurons.
The cell body carries genetic information, maintains the neuron’s structure, and provides energy for cellular neuron processes.

What is the difference between multipolar, bipolar, and unipolar neurons?
Unipolar neurons have only one structure extending from the soma
 Bipolar neurons have one axon and one dendrite extending from the soma. 
Multipolar neurons contain one axon and many dendrites;
Experiment 2: Microscopic Slide Examination of Skin
Post-Lab Questions
Identify the indicated components in the slide below.
A _____Dermis_______________
B_____sweat gland____________
C______subcutaneous fat_______________
D_____Subcutaneous layer________________
Indicate whether the statement pertains to the epidermis or dermis.
This layer consists of the papillary layer and the reticular layer. ___dermis___________
Composed of keratinized, squamous epithelium. _____epidermis_________
Langerhans cells and Merkel cells reside in this layer. ___epidermis___________
Composed of dense, irregular connective tissue. _dermis_____________
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