11. Animal Forms and Function

Question 1

Cell Organizations

Answer 1

1. Tissues - groups of similar cells performing common function. 4 categories: Epithelial (outer skin layers and internal protective coverings), Connective tissue (bone, cartilage, blood), Nervous tissue, Muscle tissue
2. Organ - group of different tissues working together to perform a particular function. ex. heart
3. Organ system - two or more organs working together. ex. digestive system: mouth, stomach, small and large intestine, pancreas, liver

Question 2

Negative Feedback

Answer 2

• sensing mechanism (receptor) detects change in condiitons beyond specific limits. Control center (or integrator) evaluates the change and activates a second mechanism (effector) to control conditions.

Question 3

Positive feedback examples

Answer 3

• childbirth (labor contractions)
• lactation (milk production increases in response to an increase in nursing)
• sexual orgasm

Question 4

Thermoregulation. Animals can be loosely grouped into two groups based on how body temperature is maintained:

Answer 4

1. Ectotherms - obtain body heat from environment. Since their temp. often vary w/ environment temp, they are sometimes referred to as poikilotherms (changing temperature). ex. most invertebrates, amphibians, reptiles, and fish. Because many of these animals may feel cold to the touch, they are called “cold blooded” animlas
2. Endotherms are animals that generate their own body heat. AKA homotherms because they maintain constant internal temp and “warm blooded” because their temp is relatively warm compared to ectotherms.

Question 5

Animal temperature regulation:

Answer 5

1. Cooling by evaporation. many animals lose heat by sweating. liquid —-> gas (endergonic), body heat removed when water vaporizes.
2. Warming by metabolism. muscle contraction and other metabolic activities generate heat. ex. shivering warms animals from heat generated by muscle contractions
3. Adjusting surface area to regulate temperature. Extremities of bodies add considerable surface afea to body. By changing volume of blood that flows to these areas by changing diameter of blood vessel, heat can be lost or conserved. ex. in hot environments, elephants and jackrabbits increase blood flow to their large ears to reduce body temperature.

Question 6

Gas Exchange Mechanisms Found in Animals:

Answer 6

1. Direct with environment - some animals are small enough to allow gas exchange directly with outside environment. Many of these animals, such as Platyhelminthes (flatworms), typically have large surface areas, and every cell either is exposed to outside environment or is close enough that gases are available by diffusion through adjacent cells. In larger animals, such as Annelida (segmented worms), gas exchange through skin is augmented by a distribution system (circulatory system) just inside the skin.
2. Gills - evaginated structures or outgrowth from the body that create a large surface area over which gas exchange occurs. Inside the gills, a circulatory system removes oxygen and delivers waste CO2.
   - Countercurrent exchange between the opposing movements of water and the underlying blood through blood vessel maximizes diffusion of O2 into blood and CO2 into water.
3. Tracheae. Insects have chitin-lined tubes, or tracheae, that permeate their bodies. Oxygen enters (or CO2 exits) the tracheae through openings called spiracles; diffusion occurs across moistened tracheal endings.
4. Lungs. Invaginated structures, or cavities within body of an animal. Book lungs, occuring in many spiders, are stacks of flattened membranes enclosed in an internal chamber.