lecture 1_animal cell types and tissues

Biology 11 (Fundamentals of Biology I)

Instructor: EAA, IKCF, SDJ, JPQ

Part V. ANIMALS: Form and Function

Main References: (1) Biology by Campbell and Reece

(2) Integrated Principles of Zoology by Hickman et al.

ANIMALS : Form and FunctionA. Animal Cell Types and TissuesB. Animal Systems and Processes

1. Support and Protection2. Movement3. Digestion and Nutrition4. Gas Exchange5. Transport/Circulation6. Excretion and Osmoregulation7. Regulatory Mechanisms

• Life is characterized by hierarchical levels of organization, each with emergent properties.

1. Protoplasmic grade of organization– unicellular organisms– all life functions are confined within the boundaries

of a single cell– protoplasm is differentiated into organelles

Levels of Organization in Organismal Complexity

Paramecium

2. Cellular grade of organization– aggregation of cells that are functionally

differentiated– a division of labor is evident


Volvox

3. Cell-tissue grade of organization– aggregation of similar cells into definite patterns of

layers, thus becoming a tissue


4. Tissue-organ grade of organization– an aggregation of tissues into organs


Planaria

5. Organ-system grade of organization– organs work together to perform some function– systems are associated with basic body functions


Ribbon worm

Animal Cell Types

Four main categories of animal tissues

1. Epithelial Tissue

2. Connective Tissue

3. Muscular Tissue

4. Nervous Tissue


• covers the outside of the body and lines organs and cavities within the body

• compact; occurs in sheets of tightly packed cells

• little intercellular substance

• polarized


• the free surface of the epithelium is exposed to air or fluid

• the cells at the base of the barrier are attached to a basement membrane, a dense mat of extracellular matrix (now called basal lamina)

• structures on free surfaces: microvilli, cilia, flagella

– cells are closely joined and in many epithelia, the cells are riveted together by tight junctions

– animals have 3 main types of intercellular links: tight junctions, desmosomes, and gap junctions


Tight junction

0.5 µm

• membranes of adjacent cells are fused, forming continuous belts around cells

• prevent leakage of extracellular fluid across a layer of epithelial cells

Desmosome1 µm

• fasten cells together into strong sheets, much like rivets

• reinforced by intermediate filaments of keratin

• attach muscle cells to each other in a muscle

Gap junction

0.1 µm

• provide cytoplasmic channels between adjacent cells

• salt ions, sugar, amino acids, and other small molecules can pass


Function Organ Tissue/cellprotection skin squamousabsorption intestine columnarsecretion stomach glandularexcretion kidney cuboidal

Types:• simple epithelium

• stratified epithelium


Types of epithelial cells:

• Cuboidal – like dice

• Squamous – flat like tiles

• Columnar – like bricks on end

• composed of flattened cells

• form a continuous delicate lining of blood capillaries, lungs, and other surfaces

• permits the passive diffusion of gases and tissue fluids into and out of cavities

• consists of 2 to many layers of cells

• adapted to withstand mild mechanical abrasion

• basal layers of cells undergoes continuous mitotic divisions

• lines the oral cavity, esophagus, anal canal, vagina of mammals; skin

• short, boxlike cells

• usually lines small ducts and tubules

• may have active secretory and absorptive functions

collecting duct in kidney

• like cuboidal epithelium but cells are taller

• found on highly absorptive surfaces such as intestinal tract and female reproductive tract

• in some organs cells may be ciliated

roof of mouth of toad

• consists of at least two layers of cells

• found along some areas of the anorectal region and salivary duct

stratified columnar epithelium (salivary duct)

• a type of stratified epithelium

• specialized to accommodate great stretching

• found in the urinary tract and bladder

Glandular epithelia, absorb or secrete chemical solutions

Types based on how products are released:a. exocrine (unicellular or multicellular)

b. endocrinec. mixed (e.g., pancreas)

Special names of some epithelial tissue:

a. mesothelium – squamous cells lining serous cavities such as peritoneal and pleural cavities and lining of visceral organs

b. endothelium – lining of blood and lymph vessels

• mechanical support

• exchange of metabolites between blood and tissues


• storage of energy reserve in adipose tissues

• bind structures to preserve integrity of organization

• protection against infection

• repair

• paucity of cells; more intercellular substance (fibers and ground substance)


• the extracellular matrix generally consists of a web of fibers embedded in a uniform foundation that may be liquid, jellylike, or solid


• amorphous ground substance

- glycosaminoglycans such as chondroitin sulfate

- permit diffusion of nutrients, substances, water, gases, and wastes

- important in areas where small blood vessels are absent


A. fixed

- fibroblast/fibrocyte- mesenchymal

- adipose

Types of cells:

- fixed macrophage

B. wandering (from blood)

- monocyte- lymphocyte

- plasma cell- eosinophil

- mast cell

Three kinds of connective tissue fibers:• Collagenous fibers (white)

– made of collagen– nonelastic and do not tear easily when pulled

lengthwise

• Elastic fibers (yellow)– long threads of elastin– elastin fiber provides a rubbery quality

• Reticular fibers (branching)– very thin and branched– composed of collagen– they form a tightly woven fabric that joins

connective tissue to adjacent tissues

33

Diagram of Fibrous Connective Tissue

Major types of connective tissues in vertebrates

A. Fibrous connective tissue– dense due to its large

number of collagenous fibers

– the fibers are organized into parallel bundles

– forms tendons and ligaments


B. Loose connective tissue– binds epithelia to underlying tissues– functions as packing materials, holding organs in

place– has all three fiber types

• two cell types predominate in its fibrous mesh

- fibroblasts- macrophages


C. Adipose tissue

– specialized form of loose connective tissue

– store fat in adipose cells

– pads and insulates the body


D. Cartilage

– has an abundance of collagenous fibers embedded in a rubbery matrix made of a substance called chondroitin sulfate, a protein-carbohydrate complex

– chondrocytes secrete collagen and chondroitin sulfate


• Hyaline cartilage– bluish white, translucent, and homogenous– has significant proportion of collagen fibers– covers joint surfaces and rib ends– present in the nose, larynx, and trachea– skeletal cartilage in the embryos of all vertebrates– skeletal cartilage of adults sharks and rays– support and reinforcement

• Elastic cartilage– contains fine collagenous fibers and many elastic

fibers– external ears, eustachian tube, epiglottis– maintains a structure’s shape while allowing great

flexibility

• Fibrocartilage– contains many large collagenous fibers– intervertebral disks, pubic symphysis, disks of knee

joint, and pads between femur and tibia– absorbs compression shock

Collagen fiber

Chondrocyte in lacuna

E. Bone– the skeleton supporting most vertebrates– mineralized connective tissue– Osteoblasts deposit a matrix of collagen– then, calcium, magnesium, and phosphate ions

combine and harden within the matrix into the mineral hydroxyapatite

Copyright © 2002 Pearson Education, Inc., publishing as Benjamin Cummings


F. Blood– the matrix is a liquid called plasma, consisting of

water, salts, and a variety of dissolved proteins

– suspended in the plasma are erythrocytes, leukocytes and cell fragments called platelets



Plasma (55 %)1. water (90% of plasma) 3. gases (O2, CO2, N)

2. dissolved solidsa. proteins– fibrinogen (synthesized by the liver)– albumin (synthesized by the liver)– globulinb. supplies for cells (glucose, fats and fat-like

substances, amino acids, salts)c. cell products (enzyme, hormones, antibodies)d. cellular waste products (urea, uric acid)

Blood

Formed elements (45 %)1. red blood cells (erythrocyte)

- biconcave- transport of O2 and CO2

- nucleated in fish, amphibians, reptiles, and birds2. white blood cells (leukocyte/leucocyte)

- granular leukocyte/granulocyte/polymorphonuclear leukocyte/polymorph- agranular leukocyte/agranulocyte/non-glanular leukocyte/mononuclear

Blood

Formed elements (45 %)3. platelets

- found within the confines of blood vessels- for blood coagulation- no nucleus; formed from megakaryocyte- called thrombocyte in amphibian, reptile, and bird

Blood

Type % Nucleus Cytoplasmic granule/cytoplasm

Other features/functions

A. granulocyte

1. neutrophil 60-75 2-5 or more thin lobes, connected by slender chromatic threads

fine; don’t stain well at neutral pH with either acid or basic stain

phagocytic

2. eosinophil 2-5 2 oval lobes linked by thread-like chromatin

granules, coarse; stain pinkish red with acid stain

against helminthic infections

3. basophil 0.5-2 nuclei stain very faintly, often obscured by cytoplasmic granules; U or J-shaped

stain blue with basic dye

inflammatory reaction

Types of White Blood Cells

Type % Nucleus Cytoplasmic granule/cytoplasm

Other features/functions

B. agranulocyte

1. lymphocyte 20-25 large, somewhat spherical with some indentations and only slightly concentric position

narrow rim of cytoplasm

smallest; antibody production

2. monocyte 3-8 nuclei vary slightly, indented ovals to horse-shoe shaped structure

large amount of cytoplasm

biggest; becomes macrophage; phagocytic

Types of White Blood Cells

• composed of long cells called muscle fibers that are capable of contracting when stimulated by nerve impulses

• most abundant tissue in most animals

3. Muscle Tissue

• muscle contraction accounts for most of the energy-consuming cellular work in active animals

• spindle-shaped cells, each with a single nucleus • cells have no striations • double innervation by parasympathetic and

sympathetic nervous sytem; involuntary • blood vessel walls and walls of the digestive tract

• functions in movement of substances in lumens of body

smooth muscle

• has cylindrical and striated cells with multiple nuclei (syncitial)

• occurs in muscles attached to skeleton

• functions in voluntary movement of body

skeletal muscle

• single innervation by motor nerve

• has cylindrical but branching striated cells, each with a single nucleus

• double innervation by parasympathetic and sympathetic nervous system; involuntary

• occurs in the wall of the heart

• functions in the pumping of blood

cardiac muscle

http://upload.wikimedia.org/wikipedia/commons/8/89/Illu_muscle_structure.jpg

• irritability and conductivity; senses stimuli and transmits signals from one part of the animal to another

• neuron – functional unit of nervous tissue

4. Nervous Tissue

Types of neurons:• sensory (afferent)• motor (efferent)• interneuron

http://upload.wikimedia.org/wikipedia/commons/0/00/Illu_nerve_structure.jpg

Animal Body Plans

Symmetry– refers to balanced proportions– correspondence in size and shape of parts on

opposite sides of a median plane

• any plane passing through the center divides a body into equivalent or mirrored halves

• found chiefly among some unicellular forms

• rare in animals

• best suited for floating and rolling

Spherical Symmetry

• body can be divided into similar halves by more than two planes passing through the longitudinal axis

• found in some sponges and hydras, jellyfish, sea urchins

• usually sessile, free floating or weakly swimming

Radial Symmetry

• only two planes passing through the longitudinal axis produce mirrored halves because of some part that is single or paired

• comb jellies

Biradial Symmetry

• body can be divided along a sagittal plane into mirrored portions – right and left halves

• much better suited for directional (forward) movement

• strongly associated with cephalization

Bilateral Symmetry

Segmentation

• metamerism

• serial repetition of similar body segments along the longitudinal axis of the body

• segment (metamere or somite)

lecture 1_animal cell types and tissues

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