General Biology 1 Module 2 PDF

Name: Governor Pack Road, Baguio City, Philippines 2600 Tel. Nos.: (+6374) 442-3316, 442-8220; 444-2786; 442-2564; 442-8219; 442-8256; Fax No.: 442-6268 Grade Level/Section: Email: [email protected]; Website: www.u...

Name: Governor Pack Road, Baguio City, Philippines 2600 Tel. Nos.: (+6374) 442-3316, 442-8220; 444-2786; 442-2564; 442-8219; 442-8256; Fax No.: 442-6268 Grade Level/Section: Email: [email protected]; Website: www.uc-bcf.edu.ph MODULE 2 – General Biology 1 Subject Teacher: CELL TYPES Learning Objectives: a. Classify the different cell types (of plant/animal tissues) and specify the function(s) of each. VARIATION IN ANIMAL CELLS How are tissues classified? Some cells act as individual cells and are not attached to one another. Red blood cells are a good example. Their main function is to transport oxygen to other cells throughout the body, so they must be able to move freely through the circulatory system. Many other cells, in contrast, act together with other similar cells as part of the same tissue, so they are attached to one another and cannot move freely. For example, epithelial cells lining the respiratory tract are attached to each other to form a continuous surface that protects the respiratory system from particles and other hazards in the air. Many cells can divide readily and form new cells. Skin cells are constantly dying and being shed from the body and replaced by new skin cells, and bone cells can divide to form new bone for growth or repair. Some other cells, in contrast, such as certain nerve cells, can divide and form new cells only under exceptional circumstances. That’s why nervous system injuries such as a severed spinal cord generally cannot heal by the production of new cells, resulting in a permanent loss of function. Many human cells have the primary job of producing and secreting a particular substance, such as a hormone or an enzyme. For example, special cells in the pancreas produce and secrete the hormone insulin, which regulates the level of glucose in the blood. Some of the epithelial cells that line the bronchial passages produce mucus, a sticky substance that helps trap particles in the air before it passes into the lungs. All the different cell types within an individual human organism are genetically identical, so no matter how different the cells are, they all have the same genes. How can such different types of cells arise? The answer is the differential regulation of genes. Cells with the same genes can be very different because different genes are expressed depending on the cell type. Bone Cells - There are four main subtypes of bone cells, as shown in the diagram below. - Four sub-types of bone cells in the human skeletal system. - (CC BY-SA 4.0 via Lumenlearning.com)  - Each type has a different form and function: a. Osteocytes are star-shaped bone cells that make up the majority of bone tissue. They are the most common cells in mature bone and can live as long as the organism itself. They also control the function of bone cells called osteoblasts and osteoclasts. b. Osteoblasts are cells with single nuclei that synthesize new bone. They function in organized groups of connected cells called osteons to form the organic and mineral matrix of bone. c. Osteogenic cells are undifferentiated stem cells that differentiate to form osteoblasts in the tissue that covers the outside of the bone. d. Osteoclasts are very large, multinucleated cells that are responsible for the breakdown of bones through resorption. The breakdown of bone is very important in bone health because it allows for bone remodeling White Blood Cells - White blood cells (also called leukocytes) are even more variable than bone cells. All of them are immune system cells involved in defending the body, but each subtype has a different function. They also differ in the normal proportion of all leukocytes they make up. Five subtypes of white blood cells are shown in the figure below. a. Monocytes make up about 5 percent of leukocytes. They engulf and destroy (phagocytize) pathogens in tissues. b. Eosinophils make up about 2 percent of leukocytes. They attack larger parasites and set off allergic responses. c. Basophils make up less than 1 percent of leukocytes. They release proteins called histamines that are involved in inflammation. d. Lymphocytes make up about 30 percent of leukocytes. They include B cells and T cells. B cells produce antibodies against non-self-antigens, and T cells destroy virus-infected cells and cancer cells. e. Neutrophils are the most numerous white blood cells, making up about 62 percent of leukocytes. They phagocytize single-celled bacteria and fungi in the blood. - - - Five sub-types of human white blood cells in the human immune system. - (CC BY 3.0; BruceBlaus via Wikimedia.org) TISSUES Groups of connected cells form tissues. The cells in a tissue may all be the same type or they may be of multiple types. In either case, the cells in the tissue work together to carry out a specific function. There are four main types of human tissues: o Connective Tissue o Epithelial Tissue o Muscle Tissue o Nervous tissues  FOUR MAIN TYPES OF HUMAN TISSUES 1. Connective Tissue The most diverse and abundant of all tissues, connective tissue holds cells together and supports the body. Connective tissue is made up of cells suspended in a non-cellular matrix. The matrix (also known as ground substance) is secreted by the connective tissue cells and determines the characteristics of the connective tissue. General features of connective tissues. The Matrix of most connective tissues is made up of ground substance and protein fibers. There are cells suspended in the matrix. (CC BY 2.5; Sunshineconnelly via Wikimedia.org) It is the consistency of the matrix that determines the function of the connective tissue. The matrix can be liquid, gel-like or solid, all depending on the type of connective tissue. For example, the extracellular matrix of bone is a rigid mineral framework. The extracellular matrix of blood is liquid plasma. Connective tissues such as bone and cartilage generally form the body's structure The image summarizes the various categories of connective tissues found in the human body. (CC BY-NC 3.0; PowePoint; Mandeep Grewal) Types of connective tissue include: 1. Connective Tissue Proper- Fibroblast cells are responsible for synthesizing protein fibers for the matrix. Collagen fibers are strong, elastic fibers are flexible and reticular fibers form a supportive framework for organs and basement membranes. There are two subcategories of connective tissue proper. a. Loose connective tissue proper- Thin and soft, this tissue contains many collagens and elastic fibers in a jell-like matrix. The cells in loose connective tissue are not close together. This tissue functions in binding the skin to underlie structures. There are three types of loose connective tissue.  This is a loose connective tissue that consists of fat cells with a little extracellular matrix. It stores fat for energy and provides insulation (CC BY 3.0; OpenStax College) o Areolar connective tissue – A common form of loose connective tissue found in the skin and mucous membranes, where it binds the skin or membrane to underlying tissues such as muscles. It is also found around blood vessels and internal organs where it links and supports them. o Adipose connective tissue- Commonly known as fat. This tissue contains fat cells that are specialized for lipid storage. In addition to storing energy, this also cushions and protects organs. o Reticular connective tissue- is mostly composed of reticular protein fibers which make a skeleton, known as stroma, for the lymphatic and white blood cells. This type of tissue is found in spleen and other lymphatic system structures. Reticular Connective Tissue. This is a loose connective tissue made up of a network of reticular fibers that provides a supportive framework for soft organs. (CC BY 3.0; OpenStax College) b. Dense connective tissue proper- This tissue consists of three categories, dense regular connective tissue, dense irregular connective tissue, and elastic connective tissue. These tissues differ on the arrangement and composition of the fibrous elements of the extracellular matrix. o Dense regular connective tissue has extracellular fibers that all run in the same direction and plane. Muscle tendons are a type of dense regular connective tissue. o Dense irregular connective tissue contains collagen and elastic fibers which are found running in all different directions and planes. The dermis of the skin is composed of dense irregular connective tissue. o Elastic connective tissue is made up of freely branching elastic fibers with fibroblasts in the spaces between the fibers, this tissue allows the kind of stretch that is found in the walls of arteries. (a) Dense regular connective tissue consists of collagenous fibers packed into parallel bundles. (b) Dense irregular connective tissue consists of collagenous fibers interwoven into a mesh-like network (CC BY 3.0; OpenStax College via wikimedia.org)  2. Cartilage - This connective tissue is relatively solid and is a non- vascularized tissue (does not have a blood supply). The matrix is produced by cells called chondroblasts. When these cells slow down, they reside is small spaces called lacunae. These mature cells in the lacunae are called chondrocytes. There are three types of cartilage: hyaline cartilage, elastic cartilage, and fibrocartilage. a. Hyaline cartilage is the most common type of cartilage, contains many collagen fibers and is found in many places including the nose, between the ribs and the sternum and in the rings of the trachea. b. Elastic cartilage has many elastic fibers in the matrix and supports the shape of the ears and forms part of the larynx. c. Fibrocartilage is tough and contains many collagen fibers and is responsible for cushioning the knee joint and for forming the disks between the vertebrae. Cartilage is a connective tissue consisting of collagenous fibers embedded in a firm matrix of chondroitin sulfates (CC BY 3.0; OpenStax College) 3. Bone - A hard, mineralized tissue found in the skeleton. The bone matrix contains many collagen fibers as well as inorganic mineral salts, calcium carbonate, and calcium phosphate, all features that make it a very rigid structure. Bone cells, called osteoblasts, secrete the osteoid substance that eventually hardens around the cells to form an ossified matrix. The osteon forms the basic unit of compact bone. Within the osteon, the osteocytes (mature bone cells) are located in lacunae. Because the bone matrix is very dense, the osteocytes get their nutrition from the central canal via tiny canals called canaliculi. - The image shows a micrograph as well as an illustration of the cross-section of the compact bone tissue. The osteon, osteocytes, central (Haversian) canal, and canaliculi are visible. (Modified by Mandeep Grewal from Bone drawing CC BY-SA 2.5; BDB via Wikimedia.org, and tissue micrograph CC BY-SA 4.0; Darshani Kansara via Wikimedia Commons)  4. Blood - made up of plasma (i.e., liquid extracellular matrix); contains water, salts, and dissolved proteins; erythrocytes that carry oxygen (RBC), leukocytes for defense (WBC), and platelets for blood clotting. The cells and cellular components of human blood are shown. Red blood cells deliver oxygen to the cells and remove carbon dioxide. White blood cells are involved in the immune response. Platelets form clots that prevent blood loss after injury. (CC BY-SA 4.0 via Lumenlearning.com) 2. Epithelial Tissue This type of tissue is commonly seen outside the body as coverings or as linings of organs and cavities. Epithelial tissues are characterized by closely-joined cells with tight junctions i.e., a type of cell modification. Being tightly packed, tight junctions serve as barriers for pathogens, mechanical injuries, and fluid loss. Types of human epithelial tissues, including their locations and functions:  (CC BY 3.0; OpenStax College via wikimedia.org) 3. MUSCLE TISSUE These tissues are composed of long cells called muscle fibers that allow the body to move voluntary or involuntary. Movement of muscles are a response to signals coming from nerve cells. In vertebrates, these muscles can be categorized into the following: a. Skeletal muscles are striated, or striped in appearance, because of their internal structure. These are attached to bones, and when they pull on the bones, they enable the body to move. Skeletal muscles are under voluntary control. b. Smooth muscles are nonstriated muscles. They are found in the walls of blood vessels and in the reproductive, gastrointestinal, and respiratory tracts. Smooth muscles are not under voluntary control. c. Cardiac muscles are striated and found only in the heart. Their contractions cause the heart to beat. Cardiac muscles are not under voluntary control. The body contains three types of muscle tissue: (a) skeletal muscle, (b) smooth muscle, and (c) cardiac muscle. (CC BY 3.0; OpenStax College via wikimedia.org) 4. NERVOUS TISSUE It is made up of neurons and other types of cells generally called glial cells. Neurons transmit electrical messages and the other cells play supporting roles. Nervous tissue makes up the central nervous system (mainly the brain and spinal cord) and peripheral nervous system (the network of nerves that runs throughout the rest of the body). There are four types of nervous tissues: a. Gray matter is nervous tissue that is found only in the brain and spinal cord which is also called the central nervous system. Gray matter is mostly composed of the cell bodies of the neurons. Gray matter is important for information processing. b. White matter is nervous tissue that is found in the brain and spinal cord, where it connects and facilitates communication between gray matter areas. White matter is also found in the nerves of the peripheral nervous system. c. Nerves make up most of the peripheral nervous system. They are long, branching tissues that carry electrical messages between the central nervous system and the remainder of the body. d. Ganglia (singular, ganglion) are also found in the peripheral nervous system. Ganglia are mostly made up of cell bodies of neurons outside of the central nervous system. They are tissues that act as relay points for messages transmitted through nerves. Image source: http://people.eku.edu/ritchisong/301notes2.htm PLANT TISSUES As for all animals, your body is made of four types of tissue: epithelial, muscle, nerve, and connective tissues. Plants, too, are built of tissues, but tissues. All three types of plant cells are found in most plant tissues. Three major types of plant tissues are dermal, ground, and vascular tissues. o Dermal Tissue o Ground Tissue o Vascular Tissue 1. DERMAL TISSUE Dermal tissue covers the outside of a plant in a single layer of cells called the epidermis. You can think of the epidermis as the plant’s skin. It mediates most of the interactions between a plant and its environment. Epidermal cells secrete a waxy substance called cuticle, which coats, waterproofs, and protects the above-ground parts of plants. Cuticle helps prevent water loss, abrasions, infections, and damage from toxins. This tissue includes several types of specialized cells. Pavement cells, large, irregularly shaped parenchymal cells which lack chloroplasts, make up the majority of the epidermis. Within the epidermis, thousands of pairs of bean-shaped sclerenchyma guard cells swell and shrink by osmosis to open and close stomata, tiny pores which control the exchange of oxygen and carbon dioxide gases and the release of water vapor. The lower surfaces of some leaves contain as many as 100,000 stomata per square centimeter. Epidermis - the exchange of matter between the plant and the environment. a. Trichomes are hair-like structures on the epidermal surface. They help to reduce transpiration (the loss of water by aboveground plant parts), increase solar reflectance, and store compounds that defend the leaves against predation by herbivores. b. The epidermis on below ground organs (roots) is involved with water and ion uptake c. The epidermis of Arabidopsis shows both pavement cells (A) and stomata made of sclerenchymal guard cells (B), which control water loss and gas exchange. Image source: https://www.ck12.org/book/cbse_biology_book_class_9/section/2.2/ 2. GROUND TISSUE It makes up much of the interior of a plant and carries out basic metabolic functions. Ground tissue in stems provides support and may store food or water. Ground tissues in roots may also store food. a. The ground tissue of the leaf (called mesophyll) uses the energy in sunlight to synthesize sugars in a process known as photosynthesis b. The ground tissue of the stem (called pith and cortex) develops support cells to hold the young plant upright c. The ground tissue of the root (also called cortex) often stores energy- rich carbohydrates - The ground tissue system arises from a ground tissue meristem and consists of three simple tissues: parenchyma, collenchyma, and sclerenchyma. Image Source: https://www.britannica.com/plant/angiosperm/Ground-tissue 3. V A S C U L A R TISSU E Vascular tissue runs through the ground tissue inside a plant. Plants don’t have hearts, but they do have vessels that transport water, minerals, and nutrients through the plant. These v essels are the v ascular tissue, a n d co nsist of xylem a n d p hlo e m. Xyle m a n d p hlo e m are p a c k a g e d to g et h er in b u n dles, as sh o w n in figure b el o w. a. The xyle m carries water and dissolved ions fro m the roots to ste ms and leaves. b. The phloe m carries dissolved sugars fro m the leaves to all other parts of the plant. Im a g e S ource: https://co urses.lu m e nle arnin g.co m / w m - biolo gy2/ ch a pt er/pla nt-tissu es-a n d-orga ns/ In dicot ste m s, v ascular bu n dles are arra n ge d aro u n d the p eriph ery of the gro u n d tissue. The xyle m tissue is locat e d to w ard the interior of the v ascular bu n dle, a n d p hlo e m is lo cate d to w ard th e exterior. S cleren chy m a fib ers ca p th e v ascular bu n dles. In m o n o c ot ste m s, v ascular bu n dles co m p ose d of xylem a n d p hlo e m tissu es are scattere d thro u gh o ut th e gro u n d tissu e. R efere nc es: Belard o, G. M. (2016). Ge n eral biolo gy.Philip pines:Vi b al Grou p M a n osa, S.D. et al. (2009). Bre akin g throu gh biolo gy.C & E Pu blishin g, In c. Q u e zon City, Philip pines O nline So urc e/s: Fo u n d ation, C. (n.d.). 12 Fo u n d ation. Retriev e d N o v e m b er 26, 2020, fro m https:// w w w.ck12.org/ b o o k/ cbse_ biolo gy_ b o o k_class_9/se ction/2.2/ Le arnin g, L. (n.d.). Biolo gy for M ajors II. Retriev e d N o v e m b er 26, 2020, fro m https://co urses.lu m e nle arnin g.co m / w m - biolo gy2/ ch a pter/pla nt-tissues-a n d-orga ns/ Libretexts. (2020, O ct o b er 28). 10.3: Hu m a n C ells a n d Tissues. Retriev e d N o v e m b er 26, 2020, fro m https://bio.libretexts.org/Bo o ksh elves/ H u m a n _Biology/Bo o k:_H u m a n_Biolo gy _( W a ki m _a n d _ Gre w al)/10:_I ntro d u ction_to_the_ H u m a n _ Bo d y/10.3:_H u m a n _ C ells_a n d _Tissues