Chapter 43 Flashcards
Organization of Vertebrate Body
There are four levels of organization Cells Tissues Organs Organ systems Bodies of vertebrates are composed of different cell types Humans have 210
Tissues
Groups of cells that are similar in structure and function
3 fundamental embryonic tissues are called germ layers
Endoderm, mesoderm, and ectoderm
In adult vertebrates, there are four primary tissues
Epithelial, connective, muscle, and nerve
Organs
Combinations of different tissues that form a structural and functional unit
Organ systems
Groups of organs that cooperate to perform the major activities of the body
Vertebrate body contains 11 principal organ systems
General body plan of all vertebrates is essentially a tube within a tube
Inner tube – digestive tract
Outer tube – main vertebrate body
Supported by a skeleton
Outermost layer – skin and its accessories
2 main body cavities Dorsal body cavity Forms within skull and vertebrae Ventral body cavity Bounded by the rib cage and vertebral column Divided by the diaphragm into Thoracic cavity – heart and lungs Pericardial cavity: Around the heart Pleural cavity: Around the lungs Abdominopelvic cavity – most organs Peritoneal cavity – coelomic space
Epithelial Tissue
An epithelial membrane, or epithelium, covers every surface of the vertebrate body
Can come from any of the 3 germ layers
Some epithelia change into glands—secretion
Cells of epithelia are tightly bound together
Provide a protective barrier
absorption
Epithelia possess remarkable regenerative powers replacing cells throughout life
Epithelial tissues attach to underlying connective tissues by a fibrous membrane
Basal surface – secured side
Apical surface – free side
Inherent polarity important for their function
Two general classes Simple – one layer thick Stratified – several layers thick Each class subdivided into Squamous cells – flat Cuboidal cells – about as wide as tall Columnar cells – taller than they are wide
Simple Epithelium
Simple squamous epithelium Lines lungs and blood capillaries Delicate nature permits diffusion Simple cuboidal epithelium Lines kidney tubules and several glands Simple columnar epithelium Lines airways of respiratory tract and most of the gastrointestinal tract Contains goblet cells – secrete mucus
Glands of vertebrates form from invaginated epithelia Exocrine glands Connected to epithelium by a duct Sweat, sebaceous, and salivary glands Endocrine glands Ductless – lost duct during development Secretions (hormones) enter blood
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Stratified Epithelium
2 to several layers thick
Named according to the features of their apical cell layers
Epidermis is a stratified squamous epithelium
Terrestrial vertebrates have a keratinized epithelium
Contains water-resistant keratin
Lips are covered with nonkeratinized, stratified squamous epithelium
Connective Tissues
Derive from embryonic mesoderm Divided into two major classes Connective tissue proper Loose or dense Special connective tissue Cartilage, bone, and blood All have abundant extracellular material called the matrix Protein fibers plus ground substance
Fibroblasts produce and secrete extracellular matrix
Loose connective tissue
Cells scattered within a matrix that contains a large amount of ground substance
Strengthened by protein fibers
Collagen – supports tissue
Elastin – makes tissue elastic
Reticulin – helps support the network of collagen
Adipose cells (fat cells) also occur in loose connective tissue Develop in large groups in certain areas, forming adipose tissue
Dense connective tissue Contains less ground substance than loose connective tissue Dense regular connective tissue Collagen fibers line up in parallel Makes up tendons and ligaments
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Special Connective Tissue
Cartilage
Ground substance made from characteristic glycoprotein (chondroitin) and collagen fibers in long, parallel arrays
Firm and flexible tissue that does not stretch
Great tensile strength
Found in joint surfaces and other locations
Chondrocytes (cartilage cells) live within lacunae (spaces) in the ground substance
Bone Osteocytes (bone cells) remain alive in a matrix hardened with calcium phosphate Communicate through canaliculi Blood Extracellular material is the fluid plasma Erythrocytes – red blood cells Leukocytes – white blood cells Thrombocytes – platelets
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Muscle Tissue
Muscles are the motors of vertebrate bodies
Three kinds: smooth, skeletal, and cardiac
Skeletal and cardiac muscles are also known as striated muscles
Skeletal muscle is under voluntary control, whereas contraction of the other two is involuntary
Smooth muscle—involuntary, nonstriated
nonbranching, single nucleated
Found in walls of blood vessels and visceral organs
Skeletal muscle—voluntary, striated
nonbranching, multinucleated
Usually attached to bone by tendons, so muscle contraction causes bones to move
Contract by means of myofibrils, which contain ordered actin and myosin filaments
Cardiac muscle—involuntary, striated,
Single nucleated, branching
Composed of smaller, interconnected cells
Interconnections appear as dark lines called intercalated disks
Gap junctions link adjacent cells
Enable cardiac muscle cells to form a single functioning unit
Nerve Tissue
Cells include neurons and their supporting cells (neuroglia)
Most neurons consist of three parts
Cell body – contains the nucleus
Dendrites – highly branched extensions
Conduct electrical impulses toward the cell body
Axon – single cytoplasmic extension
Conducts impulses away from cell body
Neuroglia
Do not conduct electrical impulses
Support and insulate neurons and eliminate foreign materials in and around neurons
Associate with axon to form an insulating cover called the myelin sheath
Gaps (nodes of Ranvier) are involved in acceleration of impulses
Nervous system is divided into
Central nervous system (CNS)
Brain and spinal cord
Integration and interpretation of input
Peripheral nervous system (PNS)
Nerves and ganglia (collections of cell bodies)
Communication of signal to and from the CNS to the rest of the body
Overview of Organ Systems
Communication and integration
Three organ systems detect external stimuli and coordinate the body’s responses
Nervous, sensory, and endocrine systems
Support and movement
Musculoskeletal system consists of two interrelated organ systems
Regulation and maintenance
Four organ systems regulate and maintain the body’s chemistry
Digestive, circulatory, respiratory, and urinary systems
Defense
The body defends itself
Integumentary and immune systems
Reproduction and development
The biological continuity of vertebrates
In females, the system also nurtures the developing embryo and fetus
Homeostasis
For cells to function efficiently and interact properly, internal body conditions must be relatively constant
The dynamic constancy of the internal environment is called homeostasis
It is essential for life
Negative feedback mechanisms
Changing conditions are detected by sensors (cells or membrane receptors)
Information is fed to an integrating center, also called comparator (brain, spinal cord, or endocrine gland)
Compares conditions to a set point
If conditions deviate too far from a set point, biochemical reactions are initiated to change conditions back toward the set point
Humans have set points for body temperature, blood glucose concentrations, electrolyte (ion) concentration, tendon tension, etc.
Integrating center is often a particular region of the brain or spinal cord
Effectors (muscles or glands) change the value of the condition in question back toward the set point value
Mammals and birds are endothermic
Maintain a relatively constant body temperature independent of the environmental temperature
Humans 37oC or 98.6oF
Changes in body temperature are detected by the hypothalamus in the brain
Negative feedback mechanisms often oppose each other to produce finer degree of control
Have “push–pull” action
Increasing activity of one effector is accompanied by decrease in the other
Many internal factors are controlled by antagonistic effectors—as with control of temperature
If hypothalamus detects high temperature
–promotes sweating and dilation of blood vessels in skin—dissipates heat
If hypothalamus detects low temperature
Promotes heat conservation via shivering and constriction of blood vessels in skin
Positive feedback mechanisms
Enhance a change – not common
These do not in themselves maintain homeostasis
Important components of some physiological mechanisms
Blood clotting
Contraction of uterus during childbirth
