Chapter 41: Homeostasis

Question 1

Maintaining a stable internal environment of a cell is essential because ______.

Multiple choice question.

the cell is uncomfortable changing from one environment to another

cells will divide uncontrollably if too cold or exposed to a low pH

most physiological processes do not function outside a narrow range of conditions

Answer 1

most physiological processes do not function outside a narrow range of conditions

Question 2

Homeostasis is best described as _____.

Multiple choice question.

altering the external environment to accommodate the body’s needs

maintaining a near-constant internal environment

keeping the body in a fixed and unaltered state

achieving a state of equilibrium in all body fluids

Answer 2

maintaining a near-constant internal environment

Question 3

During development in animals, cells become ______ to perform a particular function, and cells with similar properties can group together to form ______.

Multiple choice question.

specialized; colonies

specialized; tissues

undifferentiated; colonies

undifferentiated; tissues

Answer 3

specialized; tissues

Question 4

Clusters of specialized cells of a single given type are _________.

Answer 4

tissues

Question 5

Which of the following are the four main types of tissues found in animals?

Multiple select question.

Ligament

Epithelial

Muscle

Connective

Vascular

Nerve

Answer 5

Epithelial

Muscle

Connective

Nerve

Question 6

Maintaining homeostasis is important because it ensures which of the following?

Multiple choice question.

Fundamental processes operate efficiently.

The regulated variables never vary.

The consumption of energy is minimized.

Answer 6

Fundamental processes operate efficiently.

Question 7

What is the process whereby living organisms regulate their cells and bodies to maintain relatively stable internal conditions?

Answer 7

Homeostasis

Question 8

When do cells specialize and differentiate?

Answer 8

During development

Ex. muscle and blood cells

Question 9

What is a part of an animal or plant consisting of a group of cells having a similar structure and function, for example, muscle ______.

Answer 9

Tissue

Question 10

What are the three types of muscle tissue?

Answer 10

Skelatal, smooth, and cardiac

All three types produce force but differ in location and their appearence

Question 11

What is a type of muscle tissue that is attached by tendons to bones in vertebrates and to the exoskeleton of invertebrates?

Answer 11

Skeletal muscle. Under voluntary control!

Question 12

What is a type of muscle tissue that surrounds and forms part of the lining of hollow organs and tubes in vertebrate bodies; it is not under conscious control?

Answer 12

Smooth muscle.

Also part of small blood vessels and airway tubes (bronchioles). Contraction in these areas reduces blood and air flow, respectively.

These contractions direct blood flow where the body needs it most, and in the airways, to the healthiest part of the lungs.

Question 13

What is a type of muscle tissue, found only in hearts, in which physical and electrical connections between individual cells enable many of the cells to contract simultaneously? Also not under conscious control.

Answer 13

Cardiac muscle

The force that generates sufficient pressure to pump blood through an animal’s body.

Question 14

What is are networks of cells (neurons) that receive, generate, and conduct electrical signals throughout an animal’s body?

Answer 14

Nervous tissue

Question 15

What are highly specialized cells found in nervous systems of animals that communicates with other cells by electrical or chemical signals?

Answer 15

Neurons

Question 16

In animals, what is a sheet of densely packed cells that covers the body, covers individual organs, or lines the walls of various cavities inside the body?

Answer 16

Epithelial tissue

Epithelial cells are specialized to protect structures and tosecrete and absorb ions and organic molecules

Question 17

What are a variety of shapes that epithelial cells can come in? (3)

Answer 17

Cuboidal (cube shaped), squamous (flattened), and columnar (elongated)

Question 18

What are the different ways epithelial cells can form?

Not shape but formation.

Answer 18

simple (one layer of cells)

stratified (multiple layers)

pseudostratified (one layer, but with nuclei located in such a way that it appears stratified)

or, in certain cases such as in the urinary system, transitional (multiple layers with the ability to expand and contract)

Question 19

Regardless of their shape, organization into tissues, or location, all epithelial cells are?

Answer 19

Polarized, or asymmetric.

This means that one side of such a cell is anchored to or faces an extracellular matrix (ECM) called the basal lamina, or basement membrane.

The side with the ECM, of the cell itself, is called the basal or basolateral membrane.

Question 20

What are the four functions of the ECM in animals?

Answer 20

The four functions of the ECM in animals are strength, structural support, organization, and cell signaling.

Question 21

What is the other side of the cell called, which faces the internal (such as the lining of the stomach) or external (the body surface) environment of an animal?

Answer 21

The apical membrane.

So in review, we have the apical membrane and the basolateral or basal membranes with the basal membrane situated towards the ECM or basal lamina (basement membrane).

Question 22

What are groups of cells that connect, anchor, and support the structures of an animal’s body; include blood, adipose (fat-storing) tissue, bone, cartilage, loose connective tissue, and dense connective tissue?

Answer 22

Connective tissue

An important function of some types of connective tissue cells is to orm part of the ECM around cells by secreting a mixture of fibrous proteins and carbohydrates, such as glycosaminoglycans.

Question 23

How are the final characteristics of any type of connective tissue determined?

Answer 23

In part by the relative proportions and types of proteins, proteoglycans, and minerals secreted into the ECM.

The ECM serves several general functions, which include (1) providing a scaffold to which cells attach and organize themselves into more complex structures, (2) protecting and cushioning parts of the body, (3) providing mechanical strength, and (4) cell signaling—transmitting information to the cells that helps regulate their activity, migration, growth, and differentiation.

Question 24

What are mainly the two types of proteins that the ECM consists of?

Answer 24

The first type isinsoluble fiber-like proteins such as collagen and the rubber-band-like protein elastin; these proteins are often referred to as fibers.

A second category is adhesive proteins (fibronectin and laminin) that serve to organize the protein and carbohydrate components of the ECM.

Question 25

What is a collection of two or more tissues that performs a specific function or set of functions?

Answer 25

An organ.

For example, the vertebrate stomach:

• an outer covering of simple squamous epithelial tissue
• connective tissue layers covering and cementing the organ together
• layers of smooth muscle tissue, the contractions of which mechanically break up food and propel it through the stomach and into the small intestine
• nervous tissue that comes in close contact with the smooth muscle tissue and helps regulate its activity
• an inner lining of simple columnar epithelial tissue that secretesenzymes and acid (important in the digestive process) and protectivemucus into the cavity, or lumen, of the stomach

Question 26

What are different organs that work together to perform an overall function or functions in an organism?

Answer 26

Organ system

Question 27

What are the 10 organ systems in the body and what do they consist of?

Answer 27

Circulatory - Contractile element (heart orvessel); distribution network (blood vessels); blood or hemolymph

Digestive - Ingestion structures (mouth, mouthparts); storage structures (crop, stomach); digestive and absorptive structures (stomach, intestines); elimination structures (rectum, anus); accessory structures (pancreas, gallbladder)

Endocrine - All cells, tissues, organs, or glands that secrete hormones

Excretory - All organs including respiratory structures (e.g., gills and lungs) that are involved in removing soluble wastes from the body; the vertebrate urinary system is a part of the excretory system and includes the kidneys, ureters, bladder and urethra

Immune and Lymphatic - Circulating white blood cells (leukocytes); lymph organs, lymph vessels and nodes

Integumentary - Body surfaces (skin)

Muscular-skeletal - Force-producing structures (muscles); support structures (bones, cartilage, exoskeleton); connective structures (tendons, ligaments)

Nervous - Processing (brain); sensory structures; signal delivery (spinal cord, peripheral nerves and ganglia, sense organs)

Reproductive - Gonads and associated structures

Respiratory - Gas-exchange sites (gills, skin, trachea, lungs)

Question 28

What are the basic functions of the circulatory system?

Answer 28

Distributes solutes (nutrients, gases, wastes, and so on) to all parts of an animal’s body

Question 29

What are the basic functions of the digestive system?

Answer 29

Breaks complex foods into absorbable units; absorbs organic nutrients, ions, and water; eliminates solid wastes

Question 30

What are the basic functions of the endocrine system?

Answer 30

Regulates and coordinates growth, development, metabolism, mineral balance, water balance, blood pressure, behavior, and reproduction

Question 31

What are the basic functions of the excretory system?

Answer 31

Eliminates soluble metabolic wastes; regulates body fluid volume and solute concentrations

Question 32

What are the basic functions of the immune and lymphatic system?

Answer 32

Defends against pathogens

Question 33

What are the basic functions of the integumentary system?

Answer 33

Protects from dehydration and injury; defends against pathogens; in some animals, plays a role in regulation of body temperature

Question 34

What are the basic functions of the muscular-skeletal system?

Answer 34

Produces locomotion; generates force; propels materials through body organs; supports body

Question 35

What are the basic functions of the nervous system?

Answer 35

Regulates and coordinates movement, sensation, organ functions, and learning

Question 36

What are the basic functions of the reproductive system?

Answer 36

Produces gametes (sperm and egg); in some animals, provides nutritive environment for embryo and fetus

Question 37

What are the basic functions of the respiratory system?

Answer 37

Exchanges oxygen and carbon dioxide with the environment; regulates blood pH

Question 38

Why should organs not be considered functioning in isolation?

Answer 38

They depend on each other and can influence each other in many ways.

For example, signals from the nervous, circulatory, and endocrine systems strongly influence how much water the mammalian kidney retains as it forms urine, an adaptation that can be life saving under certain circumstances.

Question 39

[41.2 Start The relationship between structure and function]

What is a key principle of biology emphasized throughout?

Answer 39

Form (structure) determines function.

The appearance or structure of ananimal’s tissues and organs can often help us predict their functions.

Question 40

How is the structure of an animal’s tissue or organ predict its function?

Use an example.

Answer 40

Respiratory Systems of a grasshopper and human.

Exchanging oxygen from the environment with carbon dioxide generated by the body.

• A series of internal branching tubes composed of epithelial and connective tissues arises from one or more openings that connect with the outside environment (the mouth and nose in the mammal, and the body surface pores called spiracles in the insect).
• The tubes become much smaller and smaller as they continue to branch, eventually terminating in narrow structures that are only one cell thick.
• A. In the insect, the ends of the branching tubes (called tracheoles) are where oxygen diffuses from the air to the fluid around individual cells (and from there to intracellular fluid)
• B. In the mammal, the ends of the tubes form saclike structures called alveoli across which oxygen diffuses into the blood.

Question 41

Why does the alveoli, which are composed of extremely thin, squamous epithelial cells, shape provide a clue to their function?

Answer 41

This provides rapid diffusion of gases across them.

Imagine the resistance to oxygen diffusion if the cells were thick or scaly, like the cells of the body surface of many animals, for example. Therefore, both the gross and microscopic anatomy of the gas-exchange surfaces of respiratory systems facilitates their functions.

Question 42

What is a structural similarity found in essentially all respiratory surfaces, including gills?

This applies to all cells, tissues, and organs that mediate diffusion or absorption of a solute from one compartment to another or that require extensive cell-to-cell contacts.

Answer 42

Extensive surface area.

Consider, for instance, the finger-like projections of the small intestine of a human, the skin folds of some high-altitude frogs, the cellular extensions of neurons of a mouse, and the feathery antennae of a moth.

They all have a large surface area, which maximizes their ability to absorb nutrients (intestine), obtain oxygen by diffusion from the environment (frog skin), communicate with other cells (neurons), or detect airborne molecules (moth antennae).

Question 43

What is the ratio between a structure’s surface area and volume in which the structure is contained?

Answer 43

surface area-to-volume (SA/V) ratio

A high SA/V ratio is ideal for exchange of heat, solutes, gases, and water across a surface without contributing greatly to the mass or volume of a body part.

Question 44

What does a large increase in surface area of a structure come at the expense of?

Answer 44

Greatly increasing volume IF the shape of the structure is not changed.

As a spherical object enlarges, its volume grows relatively more than its surface area, because its surface area increases by a power of 2, whereas its volume increases by a power of 3.

For example, if the radius of a sphere is increased by a factor of 10, its surface area increases 100 times, but its volume increases 1,000 times.

Bottom line - as surface area increases, volume increases faster and the ratio becomes much smaller.

Shape counters this within the gills of fish and gas exchange and also in humans with invaginations of the intestines into finger-like projections.