An Overview of Animal Diversity (CH. 32) and Basic Principles of Animal Form and Function (CH. 40)

How is an organism classified as an animal? (4 things!)

1 - How they acquire and assimilate organic nutrients

2 - The presence of molecules and tissues that are exclusive to animals

3 - Their mode of sexually reproduction

4 - The presence of Hox genes that determine the embryonic development of nearly all animals.

What are a few differences between plants and fungi?

Plants are multicellular photo-autotrophs, while fungi are heterotrophs and mostly multicellular.

How do fungi rely on their environment to acquire organic molecules?

They do this by secreting digestive enzymes directly into their environment. These digestive enzymes break down complex organic molecules and digests them down to soluble products, small enough to be absorbed across the hyphal cells.

How is the way animals rely on their environment for organic molecules different than fungi?

Animals ingest organic molecules and digestive enzymes produced within specialized cavities, digest them down to bits small enough to be absorbed across epithelial cells.

Which tissues aid body cavities in churning and pushing food along the digestive tract?

Nervous tissue and muscle tissue

What type of substance are all cells bounded by?

All cells are bounded by a plasma membrane called the lipid bi-layer.

How do plants reinforce cells' lipid bilayers?

Plants reinforce this bi-layer by a cell wall that resembles reinforced cement where the cellulose fibers are akin to the steel beams, while the polysaccharides, like pectin, function like the cement.

Why are cell walls in plant cells important?

They are why a plant cell can imbibe water and become turgid without bursting.

How do turgid cells of plants affect their leaves?

Turgid cells can allow leaves to remain stiff and upright, tracking the shifting positions of the sun without them drooping down. The cell wall of plants therefore offers structural integrity to plant tissues

Do animal cells have cell walls?

No!

Is collagen exclusive to the animal kingdom?

Yes!

What is collagen?

Collagen is the foundation of bone upon which crystals of calcium and phosphate minerals are deposited.

How is collagen important to animals?

Together, the collagen and minerals make up the skeleton that functions as a scaffold upon which other tissues can be draped. Collagen is also the glue that binds muscle tissue to bone

What characteristics of animals allow them to move? (3 things!)

In combination, collagen, muscle and nervous tissue are what allow animals to move about.

What is the blastula, in animal reproduction?

A hollow, multicellular sphere

How do animals reproduce, in terms of haploids, diploids, zygotes, and the blastula?

In the animal kingdom, a haploid flagellated sperm joins a haploid egg to form a diploid zygote. This diploid zygote undergoes a process called cleavage that leads to the blastula.

What is gastrulation?

Gastrulation follows when an infolding emerges on the blastula. With gastrulation complete, we have essentially built ourselves a simple animal.

What is the outer body of a blastula called?

The outer body covering is called the ectoderm

What is the inner pouch of the blastula called?

The inner pouch is the endoderm that functions as the digestive cavity.

What is the embryonic gut of the blastula called?

The embryonic gut of the gastrula is called the archenteron

Why is it important that the genes controlling gastrulation be conserved through the entire evolutionary history of the animal kingdom?

With something as important as gastrulation in creating the basic form and function of animals, there can be no mutations in the genes controlling gastrulation without fundamentally changing what it means to be an animal.

What are Hox genes?

The genes in control of gastrulation and organogenesis are part of a family of genes called Hox genes

How many sets of Hox genes do invertebrates have, compared to vertebrates?

Invertebrates have only a single set of Hox genes. Within the invertebrates, some phyla, like the cnidarians, have only a few genes of the 13-gene set, while others like the annelids and arthropods have nearly the complete 13-gene set. In stark contrast, the vertebrates have four copies of the Hox gene set.

How do negative feedback loops affect animal physiology?

Negative feedback mechanisms enable animals to maintain stable internal conditions despite variation in external conditions

How do positive feedback loops affect animal physiology?

Positive feedback mechanisms accelerate physiological processes in animals to completion

What is 'drag', in terms of how it affects animals?

Drag is a force that opposes the movement of objects moving through a fluid. Expressed mathematically, drag increases as a function of the cross-sectional area of the organism orthogonal to the moving fluid. By reducing the area that is perpendicular to moving fluid, drag is also reduced.

How is drag experienced differently in fish compared to birds?

For aquatic organisms, the fluid is water-a medium much denser than air. Hence, the drag experienced by fish is much greater than that experienced by birds.

How is drag influenced by speed?

Drag also increases as a function of the velocity of the moving object relative to the fluid. But unlike density and area, drag increases at the square of velocity, meaning the faster one moves, the force resisting this movement increases at the square of that speed.

What is a drag coefficient?

A constant and dimensionless number that is a function of the overall shape of the object

How is life sustained, in terms of cells and their wastes?

Life is sustained when the individual cells are fed and wastes are eliminated.

How does surface area and volume affect how large a cell can get?

With a larger cell volume comes the requirement for more metabolite exchange that simply cannot be met by the cells surface area. The surface area to volume ratio therefore dictates how large a cell can get.

What is an ameoba?

Organisms residing outside the animal kingdom

How did amoebas find a work-around to the surface-area-to-volume ratio problem?

They have a highly infolded plasma membrane to increase the rate of exchange.

Why aren't animal cells shaped the way amoebas are?

Even if they did, it wouldn't serve much of a purpose because animal cells are not in direct contact with the external environment. As large multicellulars, the majority of our cells are far, very far, from the external environment

How do animal cells manage exchange differently than amoebas?

Instead of cells being infolded like the amoeba, multicellular animals have specialized organs with hyper exaggerated surface areas to absorb nutrients, exchange gases, and eliminate wastes in sufficient quantities to service all cells (Mammals: lungs, gut, kidneys)

Why is rapid waste removal important in animal bodies?

The need for rapid waste removal is also necessary to eliminate the risk of cells dying in a pool of their own metabolic wastes

How are cells, tissues, and organs connected?

Cells come together to form tissues, and tissues come together to form organs.

What are the four types of tissues within the animal kingdom?

They are the epithelial tissue, connective tissue, muscle tissue, and nervous tissue

What is epithelial tissue?

The epithelial tissue that covers the outside of the animal and lines the internal organs and ducts is made up of specific kinds of epithelial cells that enable the most efficient functioning of the organ

What are the specific cells that make up epithelial tissue?

The cell types include simple squamous, cuboidal, columnar, stratified squamous, and pseudo-stratified columnar epithelial cells. The differences in the shape at the cellular level have everything to do with functioning at the organ level.

What is the function of columnar epithelial cells.

The function of these cells is to produce enzymes to digest nutrients

What happens to the food after it is digested through epithelial cells?

Once absorbed into the epithelial cells, the digested food molecules move out from the basal surface and enter the lymphatic or circulatory system.

How do the interactions between food molecules and gut epithelial cells relate to enzymes and the endoplasmic reticulum?

The large number of interactions between food molecules and gut epithelial cells requires them to synthesize many kinds of enzymes. Such an endeavour necessitates a large endoplasmic reticulum and by extension a large cell size to accommodate such a prominent endomembrane system. We have the opposite requirements in the lungs.

What type of epithelial cell lines the alveoli in the lungs? Why?

There is an urgency associated with gas exchange that can only be met by paper-thin epithelial cells. The alveoli in lungs are lined with simple squamous epithelial cells. These very flat cells provide a moist thin surface for gas exchange

How does oxygen interact with simple squamous epithelial cells?

Oxygen enters into the lungs and diffuses across this molecularly thin tissue to reach the blood capillaries on the other side. Functioning as an exchange surface for gases, the large surface area of lung epithelial tissues favors fast rates of diffusion.

What are stratified squamous epithelial cells?

The lining of the oral cavity is made up of stratified squamous epithelial cells: as food wears away cells from the apical surface, they are replaced by the continuous addition of new cells from the basal surface.

What is connective tissue?

Connective tissue contains sparsely packed cells and fibers that are scattered throughout an extra cellular matrix. The matrix can be liquid, jelly-like, or solid.

What is the purpose of connective tissue?

The functions of connective tissue are many, ranging from physical and immune protection, movement, support, storage, and transport. In vertebrates, the fibers and the cells combine to form six major types of connective tissue.

How is each type of connective tissue distinguished?

Each type is distinguished by the principal constituent cells and fibers.

What is the dermis?

The dermis, located beneath the epidermis, is a type of loose connective tissue

What is the function of the dermis?

The function of the dermis is to support the overlying epithelial tissue as well as physical and immune defense.

What is a fibroblast cell?

They produce collagen fibers.

What do elastic fibres do for the dermis?

They give the dermis elasticity.

What do reticular fibres do for the overlying tissue that the dermis supports?

They anchor the tissue in place

What cells are found in the overlying tissue that the dermis supports?

Within this tissue we can expect to find fat cells and cells of the immune system, including plasma cells, mast cells, and macrophages. We also find fibroblast cells as well as elastic fibers and reticular fibers. All these cells and fibers within this image are suspended within a ground substance, the matrix.

What is fibrous connective tissue made of?

Fibrous connective tissue is principally composed of collagen

What is collagen?

Serves to anchor skeletal muscle in the form of tendons and to connect bones at joints in the form of ligaments.

What is adipose tissue? Where is it located in relation to the dermis?

Beneath the dermis is a sheet of adipose tissue. This fat is made up mostly of adipocytes that function to store fat, but cells of the immune system may also reside in the extracellular matrix.

What is blood?

Blood, contained within blood vessels, is a type of connective tissue carrying red and white blood cells, nutrients, and wastes in a liquid matrix to support the functioning of all body cells.

How are bones, osteoblast cells, and collagen related?

In bones, osteoblast cells produce collagen fibers which are hardened by calcium, phosphorus, and magnesium.

Are bones vascularized?

Yes! Like the dermis and adipose tissue, bone is also highly vascularized.

What is cartilage?

Collagen-rich tissue produced by chondrocyte cells embedded in a rubbery matrix.

What is cartilage's function?

Cartilage functions to cushion the space in between the vertebrae and other bones. It also gives the ear and nose its characteristic flexibility.

Is cartilage vascularized?

No, cartilage is avascular.

What does 'avascular' mean?

It means that something doesn't contain blood vessels.

What is muscle tissue responsible for?

Muscle tissue is responsible for all body movements

What proteins does muscle tissue contain?

It consists of protein filaments called actin and myosin.

What are the three types of muscle tissue?

Skeletal muscle tissue, smooth muscle tissue, and cardiac muscle tissue.

What is skeletal muscle

Skeletal muscles function to move the skeleton about. Skeletal muscle cells are long, threadlike, and multinucleated.

What is smooth muscle tissue?

Smooth muscle tissue produces involuntary body activities. They cells are short with tapered ends containing a single nucleus. These cells wrap around blood vessels to control blood flow to specific organs. As the smooth muscle cells contract, blood flow is reduced. Smooth muscle tissue also empties the bladder and controls peristalsis of the gut

What is cardiac muscle tissue?

Cardiac muscle tissue is responsible for the synchronized contractions of the heart. The cells are short and branched, each containing a single nucleus.

What is nervous tissue?

Nervous tissue functions in receiving, processing, and the transmission of information. Cells of the nervous tissue include neurons and various types of support cells called glia cells.

What is homeostatic control?

The complex system of checks and balances that maintains bodily stability

What is negative feedback, in the context of homeostasis?

The mechanism responsible for maintaining homeostasis

What is positive feedback, in the context of homeostasis?

Positive feedback mechanisms allow physiological responses to run their course to completion; the amplification of a stimulus until the process runs its full course.

What is heat?

Heat is defined as the transfer of kinetic energy from one particle to another.

What three ways can the body transfer heat?

This transfer of heat can occur by conduction, convection, and radiation.

What is conduction?

The definition of conduction is heat transfer across a stationery medium with a temperature gradient-the key words being stationery medium and temperature gradient.

What is conduction?

Heat transfer across a stationery medium with a temperature gradient-the key words being stationery medium and temperature gradient

What is convection?

This circular movement of air is called convection, specifically free convection. Unlike the stationary media of conduction, convection involves the movement of a fluid.

What is forced convection?

In forced convection, an external motive force is required to move the fluid. For example, a cool breeze blowing over this surface vegetation and displacing the heated air mass with cooler air.

Why is fat such a good insulator?

Fat is a great insulator because the long chain fatty acids don't vibrate as easily as smaller molecules.

How do homeotherms vary in temperature range?

Homeotherms have narrow ranges (like the unforgivingly narrow range in humans wedged between 36 and 38C)

How do poikilotherms vary in temperature range?

Poikilotherms can tolerate a wide range of temperatures

How do ectothermic poikilotherms

Ectothermic poikilotherms are thermoconformers; their source of heat is derived from their environment and can tolerate a wide range of internal conditions.

How do endothermic poikilotherms get their heat?

The least common type of animal-the endothermic poikilotherm-derives its heat from metabolism but can tolerate a wide range of internal temperatures.

How does the hypothalamus help with thermoregulation in endotherms?

The hypothalamus in the brain contains sensors that signal if body temperature falls below 36C or rises above 38C.

How do endotherms manage temperatures above the normal range?

When temperatures rise above the normal range, the body responds by dilating blood vessels near the surface of the skin.

Smooth muscle tissue relaxes, allowing the blood vessels near the surface of the skin to vasodilate and fill with blood.

With more blood flowing near the surface of the skin, more heat can be transferred through radiative and conduction heat transfer.

What is the rate of heat transfer in endotherms affected by?

The rate of transfer is entirely depended on the temperature gradient. The colder the outside air, the faster and more efficient the heat loss.

How do sweat glands help cool down

Animals can only lose heat through evaporation and not gain. Thus, in addition to vasodilation, when body temperatures rise, and the risk of heatstroke increases, sweat glands are triggered to move interstitial fluids to the surface of the skin, where it can evaporate.

What is evaporative cooling?

Water can hold a lot of heat, and when sufficiently heated, the molecules of water in the bead of sweat will evaporate, carrying the heat away. Consequently, the average kinetic energy of the bead of sweat pooled on the surface of the skin is reduced. By extension, so is the temperature.

Why is risk of heat stroke higher on hot and humid days?

If the sweat doesn't evaporate, there will be a transfer of heat back to the skin through conduction. This happens because the water and skin are two stationary media in direct contact. This will happen if the humidity in the air is very high and sweat is prevented from evaporating.

How do endotherms manage temperatures below the normal range?

When body temperatures dip below the normal range, vasoconstriction limits blood flow near the surface of the skin and thermogenesis kicks in, causing skeletal muscles to rapidly and involuntarily contract.

The transfer of potential energy from organic molecules, to ATP, to the kinetic energy of the shivering of muscles, liberates heat that serves to increase the temperature back towards the set point.

Is conforming or regulating temperature less metabolically expensive?

Conforming like an ectotherm is metabolically much less expensive than regulating.

What is basal metabolic rate?

BMRs can be measured as the number of liters of oxygen consumed per hour when the animal is completely at rest.

How is BMR related to body mass?

The BMR of any mammal is equal to its body mass raised to the power of ¾.