The Animal Body and Principles of Regulation Chapter 43 The Animal Body and Principles of Regulation

Organization of the Vertebrate Body There are levels of organization in the vertebrate body -cells -tissues -organs -organ systems

Tissues are groups of cells of a single type and function Early in development, the cells of the growing embryo differentiate into the three fundamental embryonic tissues called germ layers -endoderm -mesoderm -ectoderm • Four principal kinds of tissues in adult vertebrates -epithelial, connective, muscle, and nerve tissue

Organs and organ systems provide specialized functions -organs are body structures composed of several different types of tissues that form a structural and functional unit -organ system is a group of organs that cooperate to perform the major activities of the body • The general body plan of vertebrates is a tube within a tube, with internal support • Vertebrates have both dorsal and ventral body cavities -dorsal cavity is cranium and vertebrae -ventral: thoracic (pericardial, pleural) cavity and abdominopelvic (peritoneal) cavity

Epithelial Tissue Rows of cells exposed to open area and anchored down by a basement membrane to connective tissue Three types of epithelial cell structures -squamous, cuboidal, and columnar • Classified as simple or stratified • Function in protection, transport, and secretion -examples?

Tissues: groups of cells with a common structure and function (4 types) Anatomy: structure Physiology: function 1- Epithelial: outside of body and lines organs and cavities; held together by tight junctions basement membrane: dense mat of extracellular matrix Simple: single layer of cells Stratified: multiple tiers of cells Cuboidal (like dice) Columnar (like bricks on end) Squamous (like floor tiles) mucous membrane

Connective Tissue All CT are widely spaced apart cells in a matrix of extracellular material CT function in protecting (bone), support (cartilage), food storage (fat or adipose tissue) CT can be either proper or special

CT Proper May Be Either Loose or Dense Fibroblast cells produce and secrete the extracellular matrix (collagen and elastin fibers) Loose CT consists of cells scattered within a matrix that contains a large amount of fluid material and fibers. They provide support, insulation, food storage, and nourishment for epithelium -Adipose tissue is fat tissue • Dense CT has a lot more collagen than Loose CT making it structurally stronger. They provide flexible, strong connections -tendons of muscles

Special CT have unique characteristics Cartilage provides flexible support and is a shock absorber (intervertebral disks) Bone protects internal organs and provides rigid support for muscle attachment Blood functions as highway of immune system and primary means of communication between organs

Tissues, II 2- Connective: bind and support other tissues; scattered cells through matrix; 3 kinds: A-Collagenous fibers (collagen protein) B-Elastic fibers (elastin protein) C-Reticular fibers (thin branched collagen fibers) Loose connective tissue: binds epithelia to underlying tissue; holds organs 1-Fibroblasts- secretes extracellular proteins 2-Macrophages- amoeboid WBC’s; phagocytosis 3-Adipose tissue- fat storage; insulation Fibrous connective tissue: parallel bundles of cells 1-Tendons- muscles to bones 2-Ligaments- bones to bones; joints (BOBOLI) Cartilage: collagen in a rubbery matrix (chondroitin); flexible support Bone: mineralized tissue by osteoblasts Blood: liquid plasma matrix; erythrocytes (RBC’s) carry O2; leukocytes (WBC’s) immunity

Muscle Tissue Muscles are the motors of the vertebrate body Three types -skeletal: voluntary, moves the body -smooth: involuntary, control most actions of organs -cardiac: involuntary, controls the heart

Tissues, III 4- Muscle: capable of contracting when stimulated by nerve impulses; myofibrils composed of proteins actin and myosin; 3 types: A- Skeletal: voluntary movement (striated) B- Cardiac: contractile wall of heart (branched striated) C- Smooth: involuntary activities (no striations)

Nerve Tissue Composed of nerve cells (neurons) and their supporting cells (neuroglia) that are specialized to produce and conduct electrochemical events (impulses) Two divisions of the nervous system coordinate activity -central nervous system (CNS): the brain and spinal cord -peripheral nervous system (PNS): nerves and ganglia, collections of neuron cell bodies

Tissues, IV 3-Nervous: senses stimuli and transmits signals from 1 part of the animal to another Neuron: functional unit that transmits impulses Dendrites: transmit impulses from tips to rest of neuron Axons: transmit impulses toward another neuron or effector

Organ systems Organ: organization of tissues Digestive-food processing Circulatory-internal distribution Respiratory-gas exchange Immune/Lymphatic-defense Excretory-waste disposal; osmoregulation Endocrine-coordination of body activities Reproductive-reproduction Nervous-detection of stimuli Integumentary-protection Skeletal-support; protection Muscular-movement; locomotion Organ: organization of tissues Mesentaries: suspension of organs (connective tissue) Thoracic cavity (lungs and heart) Abdominal cavity (intestines) Diaphragm (respiration) Organ systems…...

Homeostasis The dynamic constancy of the internal environment Negative feedback mechanisms keep values within range -hypothalamus is the body’s thermostat Antagonistic effectors act in opposite directions Positive feedback mechanisms enhance a change -less common and have specialized functions in body

Internal regulation Interstitial fluid: internal fluid environment of vertebrates; exchanges nutrients and wastes Homeostasis: “steady state” or internal balance Negative feedback: change in a physiological variable that is being monitored triggers a response that counteracts the initial fluctuation; i.e., body temperature Positive feedback: physiological control mechanism in which a change in some variable triggers mechanisms that amplify the change; i.e., uterine contractions at childbirth

Metabolism: sum of all energy-requiring biochemical reactions Catabolic processes of cellular respiration Calorie; kilocalorie/C Endotherms: bodies warmed by metabolic heat Ectotherms: bodies warmed by environment Basal Metabolic Rate (BMR): minimal rate powering basic functions of life (endotherms) Standard Metabolic Rate (SMR): minimal rate powering basic functions of life (ectotherms)

The Evolution of Organ Systems The digestive system -Sponges flipped their stomachs inside out and ate stuff -earth worms obtained a one way digestive tract -vertebrates developed specialized organs for their digestive tracts

The Respiratory System -fishes have gills and let O2 diffuse in -amphibians breathe in cutaneously and have lungs -reptiles have straight up lungs -birds are weird and have a bunch of air sacs -mammals have well developed lungs

The Heart Fish have a 2 chambered heart Amphibians have a 3 chambered heart Reptiles have a 3 and a half chambered heart Mammals have a 4 chambered heart

The Brain Cephalization and the development of a brain were important steps in animal evolution -the concentration of the nervous system toward the anterior end of the organism • the flat worms were the first to cephalize • efficient response to a stimulus (during movement sensory organs encounter the environment first • Ectoderm gives rise to the nervous system -development of notochord -neural tube develops into brain -spinal column/vertebrae/cranium protect the CNS -notochord signals or directs the development of neural tube

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