copyright © 2005 pearson education, inc. publishing as benjamin cummings anatomy and physiology of...

Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings

Anatomy and Physiology of animals

Animal form and Function

Animal size and shape

Tissue structure and function

Thermoregulation- Ectotherms and Endotherms

Nutrition

Stages of food processing

Animal diversity

Invertebrates- Porifera (sponges)


Text devoted to animals• Except for Chapter 8 Animal like protists

(Amoeba and Paramecium)

• The inclusion of protozoa is part of a tradition

• Once considered a phylum (Protozoa) in the animal kingdom


Pattern of Organization• Symmetry

• Asymmetry

• Radial symmetry

• Bilateral symmetry


Figure 7.7 Asymmetry red encrusting sponge


Figure 7.8

Radial symmetry tube coral pulp


Part 2


Bilateral animals

• Bilateral symmetry = important evolutionary advancement

– Important for active, directed movement

• Anterior, posterior ends

– One side of body kept up (dorsal) vs. down (ventral)


Directed movement evolved with anterior sense organs cephalization

Cephalization

– specialization of sense organs in head end of animals


Bilateral Symmetry

• Divided along sagittal plane into two mirror images

– sagittal= divides bilateral organisms into right and left halves


• Anterior= head end

• Posterior= tail end

• Dorsal= back side

• Ventral= belly side


• Symmetry, fig. 7.9

– Median= sagittal


Other Patterns of Organization may reflect evolutionary trends

• Unicellular (cytoplasmic)- organisms consist of single cells or cellular aggregates,

– provide functions of locomotion, food acquisition, digestion, water and ion regulation, sensory perception and reproduction in a single cell.

– Cellular aggregates consist of loose association, cells that exhibit little interdependence, cooperation, or coordination of function

– Some cells may be specialized for reproduction, nutritive or structural function


• Diploblastic Organization

– Cells are organized into tissues in most animal phyla

– Body parts are organized into layers derived from two embryonic tissue layers.

– Ectoderm- Gr. ektos, outside + derm, skin gives rise to the epidermis the outer layer of the body wall

– Endoderm- Gr. Endo, within, gives rise to the gastrodermis that lines the gut


Mesoglea- between the ecto and endo and may or may not contain cells

– Derived from ecto and/or endo

– Cells form middle layer (mesenchyme)

– Layers are functionally inderdependent, yet cooperate showing tissue level organization i.e. feeding movements of Hydra or swimming movements of a jellyfish


Figure 7.10


The Triploblastic (treis, three +blaste, sprout)

• Animals described in chapters 10-22

• Tissues derived from three embryological layers

• Ectoderm- outer layer

• Endoderm- lines the gut

• Mesoderm- meso, middle, Third layer between Ecto and Endo

– Give rise to supportive cells


Figure 7.11


• Most have an organ system level of organization

• Usually bilaterally symmetrical or evolved from bilateral ancestors

• Organized into several groups based on the presence or absence of body cavity and for those that posses one, the kind of body cavity present.

• Body cavity- fluid filled space in which the internal organs can be suspended and separated from the body wall


Body cavities are advantageous 1. Provide more room for organ development

2. Provide more surface area for diffusion of gases, nutrients, and waste into and out of organs

3. Provide area for storage

4. Often act as hydrostatic skeletons (supportive yet flexible)

5. Provide a vehicle for eliminating wastes and reproductive products from the body

6. Facilitate increase in body size


What does acoelomate mean?• No coelom


Acoelomate a, without+ kilos, hollow

• Mesoderm relatively solid mass

• No cavity formed between ecto and endo

• These cells within mesoderm often called parenchymal cells

• Parenchymal cells not speciallized for a particular fnc.


What’s a coelom?• coelom=

– true body cavity

– Fluid-filled

– lined by mesoderm-derived epithelium

Earthworm


• Acoelomates lack a true body cavity

– Solid body

– no cavity b/w the digestive tract and outer body wall


Do these questions now…

• Think about aceolomate bilateral animals:

– To what domain do they belong

– “ ” kingdom ” ” ”

– What phyla include these organisms

• What is bilateral symmetry, and why was it an important evolutionary advantage

movie


Acoelomate Bilateral Animals• Consist of phyla:

– Phylum Platyhelminthes

– Phylum Nemertea

– Others…


Acoelomate Bilateral Animals

Reproductive and osmoregulatory systems

1. Simplest organisms to have bilateral symmetry

2. Triploblastic

3. Lack a coelom

4. Organ-system level of organization

5. Cephalization

6. Elongated, without appendages


Triploblastic Pseudocoelomate pseudes, false

• Body cavity not entirely lined by mesoderm

• No muscle or connective tissue associated with gut

• No mesodermal


The Triploblastic Coelomate Pattern• Coelom is a body cavity completely surrounded by mesoderm

• Peritoneum- mesodermal sheet that lines the inner body wall and serosa (outer covering of visceral organs)

• Having mesodermally derived tissue (muscle, connective tissue) enhances the function of all internal body systems.


Figure 7.12


Figure 7.3

Fig 7.3 Evolutionary groups

All descendants of a single ancestor

Includes some but not all of a members of a lineage

Groups traced to separate ancestors


Figure 7.4Fig 7.4 Vertebrate Phylogenetic tree depicts the degree of divergence from a common ancestor


Figure 7.5

Fig 7.5 Interpreting Cladograms Five taxa (1-5) and characteristics (A-H)

Symplesiomorphies- common characters in a group


Figure 7.6


• The comparative study of animals

– Reveals that form and function are closely correlated

Figure 40.1


• Physical laws and the environment constrain animal size and shape

• Physical laws and the need to exchange materials with the environment

– Place certain limits on the range of animal forms


Physical Laws and Animal Form

• Evolutionary convergence

– Reflects different species’ independent adaptation to a similar environmental challenge

(a) Tuna

(b) Shark

(c) Penguin

(d) Dolphin

(e) Seal


Exchange with the Environment

• An animal’s size and shape

– Have a direct effect on how the animal exchanges energy and materials with its surroundings

• Exchange with the environment occurs as substances dissolved in the aqueous medium

– Diffuse and are transported across the cells’ plasma membranes


• A single-celled protist living in water

– Has a sufficient surface area of plasma membrane to service its entire volume of cytoplasm

Diffusion

(a) Single cell


• Multicellular organisms with a sac body plan

– Have body walls that are only two cells thick, facilitating diffusion of materials

Mouth

Gastrovascularcavity

Diffusion

Diffusion

(b) Two cell layers


Organisms with more complex body plansHave highly folded internal surfaces specialized for exchanging materials

External environment

Food CO2 O2Mouth

Animalbody

Respiratorysystem

Circulatorysystem

Nutrients

Excretorysystem

Digestivesystem

Heart

Blood

Cells

Interstitialfluid

Anus

Unabsorbedmatter (feces)

Metabolic wasteproducts (urine)

The lining of the small intestine, a diges-tive organ, is elaborated with fingerlikeprojections that expand the surface areafor nutrient absorption (cross-section, SEM).

A microscopic view of the lung reveals that it is much more spongelike than balloonlike. This construction provides an expansive wet surface for gas exchange with the environment (SEM).

Inside a kidney is a mass of microscopic tubules that exhange chemicals with blood flowing through a web of tiny vessels called capillaries (SEM).

0.5 cm

10 µm

50 µ

m


• Animal form and function are correlated at all levels of organization

• Animals are composed of cells

• Groups of cells with a common structure and function

– Make up tissues

• Different tissues make up organs

– Which together make up organ systems


• Different types of tissues

– Have different structures that are suited to their functions

• Tissues are classified into four main categories

– Epithelial, connective, muscle, and nervous

Tissue Structure and Function


Epithelial Tissue

• Epithelial tissue

– Covers the outside of the body and lines organs and cavities within the body

– Contains cells that are closely joined


• Epithelial tissue EPITHELIAL TISSUE

Columnar epithelia, which have cells with relatively large cytoplasmic volumes, are often located where secretion or active absorption of substances is an important function.

A stratified columnar epithelium

A simplecolumnar epithelium

A pseudostratifiedciliated columnarepithelium

Stratified squamous epithelia

Simple squamous epitheliaCuboidal epithelia

Basement membrane

40 µm


Connective Tissue

• Connective tissue

– Functions mainly to bind and support other tissues

– Contains sparsely packed cells scattered throughout an extracellular matrix


CollagenousfiberElasticfiber

Chondrocytes

Chondroitinsulfate

Loose connective tissue

Fibrous connective tissue

100

µm

100 µm

Nuclei

30 µm

Bone Blood

Centralcanal

Osteon

700 µm 55 µm

Red blood cellsWhite blood cell

Plasma

Cartilage

Adipose tissue

Fat droplets

150

µm

CONNECTIVE TISSUE

• Connective tissue


Muscle Tissue

• Muscle tissue

– Is composed of long cells called muscle fibers capable of contracting in response to nerve signals

– Is divided in the vertebrate body into three types: skeletal, cardiac, and smooth


Nervous Tissue

• Nervous tissue

– Senses stimuli and transmits signals throughout the animal


• Muscle and nervous tissueMUSCLE TISSUE

Skeletal muscle100 µm

Multiplenuclei

Muscle fiber

Sarcomere

Cardiac muscle

Nucleus Intercalateddisk

50 µm

Smooth muscle Nucleus

Musclefibers

25 µm

NERVOUS TISSUE

Neurons Process

Cell body

Nucleus

50 µm


Organs and Organ Systems

• In all but the simplest animals

– Different tissues are organized into organs


Lumen ofstomach

Mucosa. The mucosa is anepithelial layer that linesthe lumen.

Submucosa. The submucosa isa matrix of connective tissuethat contains blood vesselsand nerves.

Muscularis. The muscularis consistsmainly of smooth muscle tissue.

0.2 mm

Serosa. External to the muscularis is the serosa,a thin layer of connective and epithelial tissue.

• In some organs

– The tissues are arranged in layers


• Representing a level of organization higher than organs

– Organ systems carry out the major body functions of most animals


• Organ systems in mammals


• After the energetic needs of staying alive are met

– Any remaining molecules from food can be used in biosynthesis

Organic moleculesin food

Digestion andabsorption

Nutrient moleculesin body cells

Cellularrespiration

Biosynthesis:growth,

storage, andreproduction

Cellularwork

Heat

Energylost infeces

Energylost inurine

Heat

Heat

Externalenvironment

Animalbody

Heat

Carbonskeletons

ATP


• Birds and mammals are mainly endothermic, meaning that

– Their bodies are warmed mostly by heat generated by metabolism

– They typically have higher metabolic rates


• Amphibians and reptiles other than birds are ectothermic, meaning that

– They gain their heat mostly from external sources

– They have lower metabolic rates


Size and Metabolic Rate

• Metabolic rate per gram

– Is inversely related to body size among similar animals


• An animal’s use of energy

– Is partitioned to BMR (or SMR), activity, homeostasis, growth, and reproduction

Energy Budgets

Endotherms Ectotherm

Ann

ual e

nerg

y ex

pend

iture

(kc

al/y

r)

800,000 Basalmetabolicrate

ReproductionTemperatureregulation costs

Growth

Activitycosts

60-kg female humanfrom temperate climate

Total annual energy expenditures (a)

340,000

4-kg male Adélie penguinfrom Antarctica (brooding)

4,000

0.025-kg female deer mousefrom temperateNorth America

8,000

4-kg female pythonfrom Australia

Ene

rgy

expe

nditu

re p

er u

nit

mas

s (k

cal/k

g•da

y)

438

Deer mouse

233

Adélie penguin

36.5

Human

5.5

Python

Energy expenditures per unit mass (kcal/kg•day)(b)

Figure 40.10a, b


• Mechanisms of homeostasis

– Moderate changes in the internal environment

Mechanisms of Homeostasis


• A homeostatic control system has three functional components

– A receptor, a control center, and an effectorResponse

No heatproduced

Roomtemperaturedecreases

Heaterturnedoff

Set point

Toohot

Setpoint

Control center:thermostat

Roomtemperatureincreases

Heaterturnedon

Toocold

Response

Heatproduced

Setpoint


• Most homeostatic control systems function by negative feedback

– Where buildup of the end product of the system shuts the system off


• A second type of homeostatic control system is positive feedback

– Which involves a change in some variable that triggers mechanisms that amplify the change


• Thermoregulation contributes to homeostasis and involves anatomy, physiology, and behavior

• Thermoregulation

– Is the process by which animals maintain an internal temperature within a tolerable range


• Ectotherms

– Include most invertebrates, fishes, amphibians, and non-bird reptiles

• Endotherms

– Include birds and mammals

Ectotherms and Endotherms


• In general, ectotherms

– Tolerate greater variation in internal temperature than endotherms

River otter (endotherm)

Largemouth bass (ectotherm)

Ambient (environmental) temperature (°C)

Bod

y te

mpe

ratu

re (

°C)

40

30

20

10

10 20 30 400


• Endothermy is more energetically expensive than ectothermy

– But buffers animals’ internal temperatures against external fluctuations

– And enables the animals to maintain a high level of aerobic metabolism


Nutrition

• Overview: The Need to Feed

• Every mealtime is a reminder that we are heterotrophs

– Dependent on a regular supply of food


• In general, animals fall into one of three dietary categories

– Herbivores eat mainly autotrophs (plants and algae)

– Carnivores eat other animals

– Omnivores regularly consume animals as well as plants or algal matter


• Regardless of what an animal eats, an adequate diet must satisfy three nutritional needs

– Fuel for all cellular work

– The organic raw materials for biosynthesis

– Essential nutrients, substances such as vitamins that the animal cannot make for itself


• Animals feed by four main mechanisms

Figure 41.2

Baleen

SUSPENSION FEEDERS

Feces

SUBSTRATE FEEDERS

BULK FEEDERS

FLUID FEEDERS

Caterpillar


• Homeostatic mechanisms manage an animal’s energy budget

• Nearly all of an animal’s ATP generation

– Is based on the oxidation of energy-rich molecules: carbohydrates, proteins, and fats


Glucose Regulation as an Example of Homeostasis

• Animals store excess calories

– As glycogen in the liver and muscles and as fat


• The main stages of food processing are ingestion, digestion, absorption, and elimination

• Ingestion, the act of eating

– Is the first stage of food processing


• Digestion, the second stage of food processing

– Is the process of breaking food down into molecules small enough to absorb

– Involves enzymatic hydrolysis of polymers into their monomers


• Absorption, the third stage of food processing

– Is the uptake of nutrients by body cells

• Elimination, the fourth stage of food processing

– Occurs as undigested material passes out of the digestive compartment


• The four stages of food processing

Piecesof food

Smallmolecules

Mechanicaldigestion

Food

Chemical digestion(enzymatic hydrolysis)

Nutrient moleculesenter body cells

Undigested material

INGESTION1 DIGESTION2 ELIMINATION4ABSORPTION3


Intracellular Digestion

• In intracellular digestion

– Food particles are engulfed by endocytosis and digested within food vacuoles


Extracellular Digestion

• Extracellular digestion

– Is the breakdown of food particles outside cells


• Animals with simple body plans

– Have a gastrovascular cavity that functions in both digestion and distribution of nutrients

Gastrovascularcavity

Food

Epidermis

Mesenchyme

Gastrodermis

Mouth

Tentacles

Mesenchyme

Food vacuoles

Gland cells

Flagella

Nutritivemuscularcells


• Animals with a more complex body plan

– Have a digestive tube with two openings, a mouth and an anus

• This digestive tube

– Is called a complete digestive tract or an alimentary canal


• The digestive tube can be organized into specialized regions

– That carry out digestion and nutrient absorption in a stepwise fashion

Esophagus

Mouth

Pharynx

Crop GizzardIntestine

Anus

Typhlosole

Lumen of intestine

Esophagus

Anus

Rectum

Mouth

CropGastric ceca

Anus

Intestine

Gizzard

Crop

Stomach

Mouth

Esophagus

Foregut Midgut Hindgut

(a) Earthworm. The digestive tract ofan earthworm includes a muscular pharynx that sucks food in through themouth. Food passes through the esophagus and is stored and moistened in the crop. The muscular gizzard, whichcontains small bits of sand and gravel, pulverizes the food. Digestion and absorption occur in the intestine, which has a dorsal fold, the typhlosole, that increases the surface area for nutrient absorption.

(b) Grasshopper. A grasshopper has several digestive chambers grouped into three main regions: a foregut, with an esophagus and crop; a midgut; and a hindgut. Food is moistened and stored in the crop, but most digestion occurs in the midgut. Gastric ceca, pouches extending from the midgut, absorb nutrients.

(c) Bird. Many birds have three separate chambers—the crop, stomach, and gizzard—where food is pulverized and churned before passing into the intestine. A bird’s crop and gizzard function very much like those of an earthworm. In most birds, chemical digestion and absorption of nutrients occur in the intestine.

copyright © 2005 pearson education, inc. publishing as benjamin cummings anatomy and physiology of...

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