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

• Mesentaries: suspension of organs (connective tissue)

• Thoracic cavity (lungs and heart)

• Abdominal cavity (intestines)

• Diaphragm (respiration)• Organ systems…...

• 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

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

• 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

THE END