Homework 6

Question 1

1. What are the four primary tissues in adult vertebrates? What are the three embryonic germ layers they are derived from?

Answer 1

The four tissues are epithelial, connective, muscle, and nerve. The three embryonic germ layers they are derived from are the endoderm, mesoderm, and ectoderm.

Question 2

2. What is meant by the claim that animals can be thought of as a design of multiple tubes and folds? Provide an example.

Answer 2

Most all physiological systems are tubular (except immune, endocrine, integumentary, skeletal, and muscular). Frogs are an example of being made up of tubes. The nervous system starts out from a “neural tube”. It is derived from the ectoderm but makes a separate tube.

Question 3

3. List the 11 mammalian organ systems and name their main physiological function.
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Answer 3

1. Digestive: Food processing (ingestion, digestion, absorption, elimination)
2. Circulatory: Internal distribution of materials
3. Respiratory: Gas exchange (uptake of oxygen; disposal of carbon dioxide)
4. Immune and Lymphatic: body defense (fighting infections and cancer)
5. Excretory: disposal of metabolic wastes; regulation of osmotic balance of blood
6. Endocrine: coordination of body activities (ex. Digestion, metabolism)
7. Reproductive: Reproduction
8. Nervous: coordination of body activities, detection of stimuli and formulation of responses to them
9. Integumentary: protection against mechanical injury, infection, drying out
10. Skeletal: body support, protection of internal organs
11. Muscular: movement, locomotion

Question 4

4. List two types of epithelial tissues and for each state i) their typical location, and ii) their function.

Answer 4

1. Simple epithelium (squamous): located in lining of the lungs, capillary walls, and blood vessels. Function: cells form thin layers in which diffusion can readily occur
2. Stratified epithelium (squamous): located in the outer layer of skin and lining of mouth. Function: tough layer of cells, provides protection.

Question 5

5. Explain what is meant by homeostasis using the terms: set point, response, feedback, sensor, stimulus, and response. Apply that general explanation to at least one specific example in which you identify the specific sensors, stimuli, responses, etc. involved in that example of homeostasis.

Answer 5

Homeostasis is the maintenance of a relatively stable internal physiological environment in an organism; usually involves some form of feedback self-regulation. There is a set point at which the organism is most comfortable. The organism has sensors and will give feedback on whether the set point is being reached or not. If not, the organism will create a response to the stimulus, thus getting the organism back to that set point.
-Example: Stimulus is that the body temperature deviates from the set point. Negative feedback is produced as the sensor (neurons in the hypothalamus detect the change in temperature), which produces a response (either the body temperature rising or dropping). If the body temp is below then blood vessels will contract and there will be muscle contraction (shivering). If the body temp is above then blood vessels to the skin dilate and the glands release sweat.

Question 6

6. List and define the four mechanisms of heat transfer?

Answer 6

1. Conduction: transfers heat by direct contact, as when a lizard sits on a hot rock
2. Convection: transfers heat by the movement of fluid past a surface, as when a breeze blows across a lizard’s dry skin
3. Evaporation: removes heat from a surface when a liquid turns to gas as when saliva evaporates a lizard’s moist surfaces.
4. Thermal radiation: absorption of electromagnetic energy without direct contact, as when a lizard basks in the sun.

Question 7

7. Explain a behavioral and physiological adaptation animals have for coping with extreme temperatures.

Answer 7

• Behavioral: many animals deal with variation in the environment by moving from one patch of habitat to another, avoiding areas that are unsuitable. Ex. Tropical lizard can maintain a fairly uniform body temp. in an open habitat by basking in patches of sunlight and then retreating to the shade when it becomes too hot.
• Physiological: A trait with a current functional role in the life history of an organism that is maintained and evolved by means of natural selection. Gazelles cool the brain by anatomical configuration of blood flow in relation to evaporative cooling from the nose. Capillary bed that goes through the wet nasal cavitiesevaporates aircoming in is cooler air that the warm arterial blood passes.

Question 8

8. What does the “mouse to elephant” curve explain?

Answer 8

Energy needs are not proportional to size. Resting metabolic rate is allometric function of body weight. The mouse eats 6X its body weight in one weeks, while the elephant eats 1/3 its body weight in one week.