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C
ells are the building blocks of life. In humans and other multicellular organ-isms, cells depend on one another and cooperate to maintain homeostasis in the body. With a few exceptions, even the most complex animal starts out as a singlecell, the fertilized egg, which divides almost endlessly. The resulting trillions of cells then specialize for a particular function. Some become supportive bone, others skin cells, and so on. Thus a division of labor exists, with certain groups of cells highly specialized to perform functions that benefit the organism as a whole. Cell specialization provides for sophisticated functions but involves cer-tain hazards, because when a small, specific group of cells is indispensable, any inability to function on its part can paralyze or destroy the entire body. Groups of cells that are similar in structure and function are called tissues. The four primary tissue types — epithelial, connective, muscular, and nervous — have distinct structures, patterns, and functions. To perform specific body functions, the tissues are organized into organs such as the heart, kidneys, and lungs. Most organs contain several representatives of the primary tissues, and the arrangement of these tissues determines the organ’s structure and function. The main objective of this exercise is to familiarize you with the major similarities and dissimilarities of the primary tissues. Because we will not consider epithelium and some types of connective tissue again, we emphasize them more than muscle, nervous tissue, and bone (a connective tissue), which we cover in greater depth in later exercises.
E X E R C I S E
Classification of Tissues
Pre-Lab Quiz
- How many primary tissue types are found in the human body? _________
- Epithelial tissues can be classified according to cell shape. epithelial cells are scalelike and flattened. a. Columnar c. Squamous b. Cuboidal d. Transitional
- This type of epithelium lines the digestive tract from stomach to rectum. a. simple cuboidal c. stratified squamous b. simple columnar d. transitional
- All the following are examples of connective tissue except: a. bones c. neurons b. ligaments d. tendons
- Circle the correct term. Of the two major cell populations in nervous tissue, neurons / neuroglial cells are highly specialized to receive stimuli and conduct waves of excitation to all parts of the body.
- This type of muscle tissue is found in the walls of hollow organs. It has no striations, and its cells are spindle-shaped. It is: a. cardiac muscle b. skeletal muscle c. smooth muscle
4
Materials
Microscope slides of tissue specimens will bedemonstrated and explained during the interactive Zoom session. Make sure to take notes. Attempt tomake sketches during the lecture but don't worry if it's too fast - since all Zoom sessions are recordedyou can go back and find the video of the slides.In addition, the phe pdf with the snaps of the slideswill be provided on Canvas. Below is the list of slides: Activity1 simple cuboidal, simple columnar, pseudostratified Prepared slides of simple squamous, ciliated columnar, stratified squamous (keratinized)stratified squamous (nonkeratinized), stratified cuboidal or columnar, and transitional epithelium. Activity 2: • (set 1) loose (areolar), reticular, adipose, dense regular collagenous, dense irregularcollagenous, dense elastic;
- (set 2) hyaline cartilage, fibrocartilage,elastic cartilage,
- (set 3) bone and blood. Activity 3 : skeletal muscle, cardiac muscle, smooth muscle. Activity 4 : giant multipolar neuron smear.
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Sp (^2024) A (^3)
a ____________________________________________________
b ____________________________________________________
2 Simple cuboidal epithelium
a ____________________________________________________
b ____________________________________________________
3 Simple columnar epithelium
a ____________________________________________________
b ____________________________________________________
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Mag________X
Mag________X
Mag________X
Activity 1 Slides
Procedure 1 Microscopy of Epithelial Tissues
a ____________________________________________________
b ____________________________________________________
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Mag________X
Activity 2 Slides
Procedure 1 Microscopy of Connective Tissue PropFS
5 Dense irregular collagenous CT
a ____________________________________________________
b ____________________________________________________
6 Dense elastic CT a ____________________________________________________
b ____________________________________________________
Mag________X
Mag________X
2 Reticular CT a ____________________________________________________
b ____________________________________________________
3 Adipose tissue
a ____________________________________________________
b ____________________________________________________
4 Dense regular collagenous CT a ____________________________________________________
b ____________________________________________________
Mag________X
Mag________X
Mag________X
Procedure 3 Microscopy of Bone and Blood
View prepared slides of bone and blood. Use colored pencils to draw pictures of what you see under the microscope, and label your drawings with the terms in Figures 5.8 and 5.9 (p. 116). Then (a) describe what you see, and (b) give examples of locations in the body where this tissue is found.
1 Bone
a ____________________________________________________
b ____________________________________________________
2 Blood
a ____________________________________________________
b ____________________________________________________
Activity 3
Examining Muscle Tissue Under
the Microscope
Go to station 3 of the demonstration area to examineprepared slides of skeletal, cardiac, and smooth muscle. Notice their similarities and dissimilarities in your obser-vations and in the illustrations in Figure 5 .4.
O B J E C T I V Eteristics, functions, and locations of the three muscle types 3 List the general structural charac- in the body, and identify subtypes when presented with a diagram or slide. Muscle tissue movement of some body parts. As you might expect, muscle is specialized to contract (shorten) to produce cells are elongated to provide a long axis for contraction. Skeletal muscle, the “meat,” or flesh, of the body, is at- tached to the skeleton. It is under voluntary control (con-sciously controlled). As it contracts, it moves the limbs and other external body parts. Skeletal muscle cells are long, cy-lindrical, and multinucleate (several nuclei per cell); they have obvious Cardiac muscle striations is found only in the heart. As it con- (stripes). tracts, the heart acts as a pump, propelling the blood into theblood vessels. Like skeletal muscle, it has striations, but car- diac cells are branching cells with one nucleus (or occasion-ally two) that fit together at junctions called intercalated discs cle is under involuntary control, which means that we cannot that allow cardiac muscle to act as a unit. Cardiac mus- voluntarily or consciously control the operation of the heart.
Smooth muscle is found mainly in the walls of all hol- low organs (digestive and urinary tract organs, uterus, bloodvessels) except the heart. Typically two layers run at right angles to each other, so the muscle can constrict or dilate thelumen (cavity) of an organ and also propel substances along existinguninucle-ate pathways. smooth Nomuscle striations cells areare visible, spindle-shaped. and the Smooth muscle is under involuntary control.
TABLE Characteristics of Muscle Tissues Muscle Tissue Type
Striated or Nonstriated
One or Multiple Nuclei
Size and Shape of Cells Special Features
Skeletal muscle
Cardiac muscle
Smooth muscle
Microscopy of Muscle Tissue
Examine the slides as demonstrated. Use colored pencils to sketch demonstrated specimen and label them with main features (membrane, nucleus, cytoplasm, and any additional features specific for the given cell type). For the specifics of each tissue type, use terms in the background section and in the Histology Atlas linked on the Home Page. In (a) provide at least one example of where in the body this cell type is located, and (2) it’s specific function. Indicate magnification in space labeled Mag_________X
Muscle Tissue
1ervous tissue is the primary component of the brain, the spinal cord, and the peripheral nerves. consists
of a uniTue (CM and two main cell types
. 1eurons. The neurons (1225-ahnz) are responsible for sendingand receiving messages within the nervous system. 2n your slide they are the larger of the two cell types. The large, central portion of the neuron is called the *FHOOERG*. Within the cell body we find the nucleus and many of the neuron’s organelles, including clusters of rough endoplasmic reticulum called 1LVVOERGLHV. Most neurons contain two types of long armlike processes extending from the cell body—the dendrites ('(1-dryt’z), which receive messages from other neurons, and the axon ($;- ahn), which sends messages to other neurons, muscle cells, or gland cells. . 1euroglial cells. The smaller and more numerous cells around the neurons are the QHXURJOLDOFHOOV (noor-oh-G/((-uhl). The six different types of neuroglial cells vary significantly in shape and appearance. 1euroglial cells in general perform func-tions that support the neurons or the (CM in some way.
1 Nervous tissue a ____________________________________________________
b ____________________________________________________
processesNeuronal cell bodyNeuron nucleusNeuron nucleolus^ Neuron neuroglial cellsNuclei of
FIGURE 5. Nervous tissue.
Activity 4
Examining Nervous Tissue Under
the Microscope
Go to station 4 at the demonstration area, and examine a prepared slide of a spinal cord smear. Locate a neuron, and compare it to Figure 5. 5 and the Histology Atlas. Keep the light on the microscope dim—this will help you see the cellular extensions of the neurons.
/FSWPVT Tissue
A
ll organs consist of two or more tissues that must work together to enable the organ to function properly. The study of the tissues that make up the body’s organs is called organology. Most organs are made of layers of tissues stacked upon one another and “glued” together by proteins and other compounds in the ground substance. This exercise introduces you to organology, a topic we explore repeatedly in the remainder of this lab manual. Determine the Tissue Types of Organs
Following are illustrations of two organs: a joint and the esophagus ( Fig. . ). Tissue sections from each organ have been taken, and your task is to identify each tissue. Be specific about which type of muscle, epithelial tissue, and connective tissue you identify in the organ.
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FIGURE (^) 5. Tissues making up an organ: (A) a joint; (B) the esophagus.
B
A
Review Sheet 5
Key:
7. Use the key choices to respond to the following. (Some choices may be used more than once.) 1. best suited for areas subject to friction 2. propels substances across its surface 3. most suited for rapid diffusion 4. tubules of the kidney 5. lines much of the respiratory tract 6. stretches 7. lines the small and large intestines 8. lining of the esophagus 9. lining of the bladder 10. alveolar sacs (air sacs) of the lungs
Connective Tissue 8.
9.
10. Using the key, choose the best response to identify the connective tissues described below.
pseudostratified ciliated columnarsimple columnar simple cuboidalsimple squamous stratified squamoustransitional
Key: adipose connective tissueareolar connective tissue dense fibrous connective tissue
reticular connective tissue hyaline cartilageosseous tissue fibrocartilage blood
1. attaches bones to bones and muscles to bones 2. forms your hip bone 3. composes basement membranes; a soft packaging tissue with a jellylike matrix 4. forms the larynx and the costal cartilages of the ribs 5. firm matrix heavily invaded with fibers; appears glassy and smooth
How does this structural difference reflect its function in the body? BBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBB BBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBB
What are the components of the matrix in connective tissues? BBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBB BBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBB
How are the functions of connective tissue reflected in its structure?BBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBB BBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBB
Review Sheet 5
6. matrix hard; provides levers for muscles to act on 7. insulates against heat loss; provides reserve fuel 8. makes up the intervertebral discs
Muscle Tissue
11. The terms and phrases in the key relate to the muscle tissues. For each of the three muscle tissues, select the terms or phrases that characterize it, and write the corresponding letter of each term on the answer line. Key: (^) a. striated f. voluntary k. attached to bones b. branching cellsc. spindle-shaped cells g. involuntaryh. one nucleus l.m. in wall of bladder and stomach intercalated discs d. cylindrical cellse. active during birth i. many nucleij. forms heart walls n. moves limbs, produces smileso. arranged in sheets
Skeletal muscle: _________________________________________ Cardiac muscle: ________________________________________ Smooth muscle: ________________________________________
Nervous Tissue
12. In what ways are neurons similar to other cells?
How are they different? How does the special structure of a neuron relate to its function?
Sketch a typical neuron below and label its parts including body axon, dendrites, axon hillock, synapses, nucleus, 1issl body,Schwann cells, nodes of 5anvier, microglia.
Review Sheet 5
(k) (l)
(i) (j)
(g) (h)
