BISC208 Exam 2

What is an animal?

Animals are multicellular eukaryotes, lacking cell walls. They use ingestion and are heterotrophs.

Animal reproduction?

Nearly all animals reproduce sexually. The adults are diploid, meaning their gametes are haploid and fuse to form a diploid zygote.

Types of Body Symmetry:

1. Radial symmetry (Cnidaria, coral)

2. No symmetry (Parazoa, jellyfish)

3. Bilateral symmetry (Bilateria, crabs)

What is a blastula?

A hollow ball of cells formed by a zygote dividing by mitosis.

What happens to one side of the blastula during development?

One side of the blastula folds in and the cells rearrange to form a gastrula.

What are the three germ layers formed during gastrulation?

Ectoderm, mesoderm, and endoderm.

Function of endoderm

Forms a lining of the future digestive tract

Function of ectoderm

forms an outer layer that gives rise to the skin and nervous system

Function of mesoderm

forms a middle layer that will give rise to muscles and most internal organs

What forms during gastrulation in embryonic development?

The endoderm forms an opening called the blastophore.

In protostomes, what does the blastopore form?

The mouth.

In deuterostomes, what does the blastopore form?

The anus; the mouth forms later.

What is a body cavity?

A space that houses internal organs.

What is a coelom?

A fluid-filled body cavity.

What are coelomates?

Organisms that contain a true body cavity.

What are pseudocoelomates?

Organisms whose coelom is not completely lined with tissue.

What are acoelomates?

Organisms that lack a fluid-filled cavity.

Broad Differences in Animal Phyla:

1. Types of Body Symmetry

2. Number of Germ Layers

3. Features of embryonic development

Segmentation:

The body is divided into regions called segments. (Worms, Lobsters, Fish)

What is the advantage of segmentation?

It allows for specialization of body regions.

Animal Phylogeny

1. Vertebral column

2. Cranium

3. Endoskeleton of cartilage or bone

Vertebral column

The notochord is replaced by a bony or cartilaginous column of interlocking vertebrae

Cranium

Anterior end of the nerve cord forms a well-developed brain enclosed in a protective bony or cartilaginous cranium

Endoskeleton of cartilage or bone

The endoskeleton provides structural support and is composed of either bone or cartilage

Mammals have four characteristics that set them apart from other animals

1. Mammary glands

2. Hair

3. Specialized teeth

4. Enlarged Skull

Mammary Glands

Females have distinctive mammary glands that secrete milk. Milk is a fluid rich in fat, sugar, protein, and vital minerals (calcium) needed by newborns

Hair

all mammals have hair. Mammals are endothermic and the hair acts as an insulator

Specialized teeth

They have highly differentiated teeth - incisors, canines, premolars, molars, which are adapted for different diets

Enlarged Skull

There is an enlarged brain that is contained in a large skull

Monotremes

egg-laying mammals

Marsupials

Have a brief gestation and give birth to tiny, embryonic offspring, that complete development while attached to the mothers nipples

Eutherians (placental mammals)

mammals that bear fully developed live young.

Organization of Animal Bodies

1. Tissues

2. Organ

3. Organ system

4. Organism

Tissue

an association of many cells that have a similar structure and function

Tissues in animal's body can be classified into four types:

1. Muscle

2. Nervous

3. Epithelial

4. Connective Tissue

Muscle tissue

consists of cells specialized to shorted, or contract, generating the mechanical forces that may produce body movement, decrease in a tube diameter or exert pressure on a fluid-filled cavity

Nervous tissue

are composed of a complex network of cells called neurons that are specialized to receive, generate and conduct electrical signals from one part of an animal's body to another

Epithelial tissue

consist of sheets of densely packed cells that cover the body of individual organs and line the interiors of various cavities inside the body

Connective tissue

connect, surround, anchor, and support the structures of an animal's body. Includes blood, adipose (fat-storing) tissue, bone, cartilage, loose connective tissue, and dense connective tissue

Organ

composed of two or more kinds of tissues arranged in various proportions and patterns

Form/Structure determines

Function (ex: compare the respiratory systems of an insect and a mammal)

What is a key feature of all respiratory surfaces?

All respiratory surfaces have an extensive surface area.

What is an example of nutrient absorption in the body?

Nutrient absorption occurs in the intestines.

What is an example of cell communication in the body?

Cell to cell communication occurs in neurons.

What is an example of waste excretion in the body?

Waste excretion occurs in the kidneys.

What is the relationship between a structure's surface area and its volume called?

The surface area/volume (SA/V) ratio.

Why is a high surface area/volume (SA/V) ratio ideal?

A high SA/V ratio is ideal for exchange of heat, solutes, gases, and water across a surface.

How do structures maximize surface area without greatly increasing volume?

Structures can fold or have variations in shape, such as the finger-like extensions in the human intestine.

Homeostasis

The process of maintaining a relatively stable internal environment despite changes in the external surroundings

Homeostatic Control System in the body:

1. A set point: normal value for a controlled variable

2. A sensor: which monitors the controlled variable

3. An integrator: compares signals from the sensor

4. An effector: which compensated for any deviation between actual value and the set point

What are the sensors responsible for regulating body temperature in mammals?

Temperature sensitive neurons in the brain and skin.

What is the role of the integrator in regulating body temperature in mammals?

A collection of neurons within the brain.

What do the signals from the integrator neurons do in temperature regulation?

They are sent via nerves to the effectors.

What are the effectors involved in regulating body temperature in mammals?

The skeletal muscles.

What happens to skeletal muscles when body temperature decreases?

The muscles contract, leading to shivering.

What is a key way that mammals generate body heat?

Shivering.

Negative Feedback loop

a mechanism that moves a variable back to its set point (Ex: Drop in blood pressure due to an injury and loss of blood)

Osmoregulators

Animals that maintain very stable internal ion concentrations and osmolarity. They maintain stable cellular levels of ions and water, but this requires considerable expenditure of energy.

What are osmoconformers?

Animals that match the osmolarity of their extracellular and intracellular fluids with their fluid environment.

How do osmoconformers regulate their osmolarity?

They match the osmolarity of their fluids with the surrounding environment.

How do osmoconformers compensate for water gain or loss?

They expend less energy and are generally limited to marine environments

Building block of the nervous system

Neuron

Nerves

neurons grouped in bundles

Four Parts of the Neuron:

1. Dendrites

2. The Cell Body

3. Axon

4. Axon Terminal

Dendrites

Branchlike parts of a neuron that are specialized to receive information. Relays info into the cell body.

The Cell Body

Relays the information down to the axon, contains the cell nucleus

Axon

a thin, long structure that transmits signals from the cell body to the axon terminal

Axon Terminal

The endpoint for the relay of information inside the nueron

Action Potential

the electrical current sent down the axon

The Synapse

the space between neurons (synaptic gap or cleft)

Resting Potential

(when the cell is not firing) is typically a fraction of a volt between the inside and the outside

What led to complex human brains

-Large brain size

-Language

-Ability to use complex tools

-Bipedalism

Four Phases of Food Processing

-Ingestion

-Digestion

-Absorption

-Egestion