chapter 42,43,44 learning objectives - Objectives-Chapter...

Objectives-Chapter 40
18:59
Concept 40.1: Physical laws and the environment constrain animal size and shape
Explain how physical laws constrain animal form
• An animal’s size and shape, features that biologists often call “body plans” or
designs” are fundamental aspects of form and function that significantly affect the
way an animal interacts with its environment. The body plan of an animal results
from a pattern of development programmed by the genome itself the product of
millions of years of evolution. The possibilities are not infinite-physical laws and the
need to exchange materials with the environment place certain limits on the range of
animal forms.
• Physical requirements constrain what natural selection can “invent”, including the
size and shape of flying animals. The laws of hydrodynamics constrain the shape that
are possible for aquatic animals that swim very fast.
Concept 40.2: Animal form and function are correlated at all levels of organization
Define cell, tissue, organ, organ system
• Cell: Life’s fundamental unit of structure and function.
• Tissue: Groups of cells with a common structure and function. Different types of
tissues have different structures that are suited to their functions.
• Organ: Different tissues are organized into organs. In some organs, the tissues are
arranged into layers.
• Organ System: Representing a level of organization higher than organs, they carry
out the major body functions of most animals. Consists of several organs and has
specific functions, but the efforts of all systems must be coordinated for the animal to
survive.

Objectives-Chapter 41
18:59
Concept 41.1: Homeostatic mechanisms manage an animal’s energy budget
Explain the homeostatic regulation of blood glucose levels
• In humans, the liver and muscle cells store energy in the form of glycogen, a polymer
made up of many glucose units. Glucose is a major fuel for cells, and its metabolism,
regulated by hormone action, provides an important example of homeostasis.
o If the body’s glycogen depots are full and caloric intake still exceeds caloric
expenditure, the excess is usually stored as fat.
o When fewer calories are taken in than are expended, fuel is taken out of the
storage depots and oxidized.
• The human body generally expends liver glycogen first and then draws on muscle
glycogen and fat.
Explain the action of the appetite regulating hormones
• The hormone leptin is one of the key long-term appetite regulators in mammals.
Leptin is produced by adipose (fat) cells.
o As adipose tissue increases, leptin levels of the blood rise, which normally cues
the brain to suppress appetite.
 This is one of the feedback mechanisms that keeps most people from
becoming obese in spite of an access to an abundance of food.