Chapter 4

Question 1

What are tissues?

Answer 1

specialized cells of the same type that perform a common function in the body.

Question 2

Name the four major tissue types. Briefly, what are their functions?

Answer 2

connective tissue
muscular tissue
nervous tissue
epithelial tissue

Question 3

What are the three basic components that all connective tissues contain? What is the matrix portion of
connective tissue?

Answer 3

specialized cells (These are living cells.),
ground substance (nonliving),
protein fibers (nonliving).

The term matrix includes ground substance and fibers.

Connective tissue consists of living cells in a nonliving matrix.

Question 4

What three types of fibers are found in connective tissue?

Answer 4

collagen, reticular, and elastic fibers

Question 5

Describe fibrous connective tissue. Distinguish among loose fibrous connective tissue, adipose tissue, and dense fibrous connective tissue.

Answer 5

Loose fibrous connective tissue (areolar) supports epithelium and many internal organs.

Adipose tissue is a specialized form of connective tissue in which cells enlarge and store fat.

Dense fibrous connective tissue contains collagen fibers packaged together and makes up tendons and ligaments.

Question 6

Describe supportive connective tissue.

Answer 6

Cartilage and bone are supportive connective tissues with a solid extracellular matrix.

Cartilage is more flexible than bone.

Question 7

Distinguish among the following types of cartilage: hyaline cartilage, elastic cartilage, fibrocartilage.

Answer 7

hyaline cartilage (at the ends of bones and comprising the fetal skeleton),

elastic cartilage (forming a flexible frame for the outer ear),

fibrocartilage (making pads in the knee and vertebral column).

Question 8

What substances are responsible for the hardness of bone?

Answer 8

The matrix of bone is hard because it contains inorganic salts, particularly calcium salts.

Question 9

Distinguish between compact bone and spongy bone.

Answer 9

Compact bone makes up the shaft of the long bone. It consists of cylindrical structural units called osteons. The central canal of each osteon is surrounded by rings of hard matrix. Bone cells are located in lacunae between the rings of matrix.

Spongy bone is made up of bars and bony plates and is lighter than compact bone.

Question 10

Describe the following liquid connective tissues: blood, lymph. What makes up the matrix of each?
What kinds of cells are found in each?

Answer 10

Blood is a connective tissue in which the matrix is a liquid called plasma. Red blood cells (erythrocytes), white blood cells (leukocytes), and platelets (thrombocytes) are in blood.

Lymph is also a fluid connective tissue. It is a clear, watery fluid derived from tissue fluid that contains white blood cells.

Question 11

Describe the function of muscle tissue

Answer 11

Muscular tissue is specialized to contract. It is composed of cells called muscle fibers.

Question 12

Distinguish among the following types of muscle: skeletal muscle, smooth muscle, cardiac muscle.
Where is each type found? Are they voluntary or involuntary? Do they have striations? What are intercalated disks?

Answer 12

Skeletal muscle is called voluntary muscle and contains stripes or striations. It is found in muscles attached to bones. Skeletal muscle cells are multinucleate.

Smooth muscle lacks striations, is composed of spindle-shaped cells, and is found in internal organs. It is also known as visceral muscle. Smooth muscle cells have one nucleus per cell. Smooth muscle is involuntary.

Cardiac muscle is also striated. It has one nucleus per cell. Cardiac muscle is involuntary and is found only in the walls of the heart. Cardiac muscle cells are branched and contain intercalated disks.

Question 13

What are the two components of nervous tissue? What are the three functions of nervous tissue?

Answer 13

Nervous tissue consists of nerve cells, called neurons, and neuroglia, the cells that support and nourish the neurons.

The nervous system serves three purposes: sensory input, integration of data, motor output.

Question 14

Describe the three parts of a neuron and their functions.

Answer 14

• dendrites to receive signals from sensory receptors or other neurons,
• cell body where the nucleus is located,
• axon to conduct nerve impulses.

Question 15

Name three kinds of neuroglial cells. What are their functions?

Answer 15

There are several types of neuroglial cells, which support, nourish, and protect neurons. Examples include microglia, astrocytes, and oligodendrocytes.

Question 16

Describe the function and location of epithelial tissue

Answer 16

Epithelial tissue covers the body and lines its cavities.

Epithelial cells are exposed to the environment on one side.

On the other side, a basement membrane joins epithelium to underlying connective tissue.

Question 17

Describe simple epithelia. What shapes are found among these cells? Where would simple epithelia
be found?

Answer 17

Simple epithelia have only a single layer of cells, which can be:
flattened (squamous),
cube-shaped (cuboidal), or
resembling rectangular columns (columnar).

This type can be found in the air sacs of lungs, in the walls of blood vessels, covering the ovaries, lining kidney tubules, and lining the digestive tract

Question 18

Describe pseudostratified columnar epithelium. Where would it be found?

Answer 18

Pseudostratified columnar epithelium is so named because it appears to be layered, but each cell actually touches the basement membrane.
This type can be found in the lining of the trachea.

Question 19

Distinguish between the following types of glandular epithelia: exocrine glands, endocrine glands.
Give examples of each.

Answer 19

When an epithelium secretes a product, it is said to be glandular.

Exocrine glands secrete their product onto the outer surface or into a cavity via a duct, while endocrine glands secrete their products directly into the bloodstream.

Question 20

What is stratified epithelium? Distinguish between stratified squamous epithelium and transitional epithelium. Where would each be found? What is keratin?

Answer 20

Stratified epithelia have layers of cells piled one on top of the other, the bottom layer touching the basement membrane.

Stratified squamous epithelium can be found in the nose, mouth, esophagus, anal canal, outer portion of the cervix, and vagina.

The outer layer of the skin contains stratified squamous epithelium reinforced by keratin.

Transitional epithelium is used to imply changeability, because it changes in response to tension. It forms the lining of the urinary bladder.

Question 21

Define: integumentary system. What is its function?

Answer 21

The integumentary system, or skin, is an example of an organ system because it contains accessory structures such as nails, hair, and glands.
Skin covers the body and protects underlying tissues from physical trauma, pathogen invasion, and water loss.

Question 22

Describe the functions of the following epidermal cells: basal cells, Langerhans cells, melanocytes.

Answer 22

The epidermis contains basal cells that produce new epithelial cells, which become keratinized as they move toward the surface.

Specialized cells called Langerhans cells phagocytize pathogens and protect the body from invading organisms.

Melanocytes produce melanin, the main pigment responsible for skin color, and protect the skin from the damaging effects of ultraviolet radiation.

Epidermal cells can also make vitamin D.

Question 23

What might be the effect of ultraviolet radiation on the epidermis?

Answer 23

Too much ultraviolet radiation is dangerous and can lead to skin cancer. Basal cell carcinoma is the most common type of skin cancer and the most curable. Melanoma is extremely serious. Steps should be taken to protect the skin from ultraviolet radiation.

Question 24

Describe the structure of the dermis of the skin. What types of tissues would be found here?

Answer 24

The dermis, a largely fibrous connective tissue, contains epidermally derived glands and hair follicles, nerve endings, and blood vessels.

Sensory receptors for touch, pressure, temperature, and pain are also present.

Question 25

Describe the following accessory organs of the skin: nails, hair follicles, arrector pili muscles, oil (sebaceous) glands, sweat (sudoriferous) glands.

Answer 25

The accessory structure of the skin includes the nails, hair follicles, oil glands, and sweat glands.

Nails are a protective covering of the distal part of fingers and toes.

Hair follicles begin at a bulb in the dermis and continue through the epidermis where the hair shaft extends beyond the skin. Contraction of the arrector pili muscles attached to hair follicles causes hair to stand on end.

Oil glands secrete sebum, and sweat glands play a role in modifying body temperature.

Question 26

Define: organ. What is an organ system?

Answer 26

A group of tissues performing a common function is an organ. The organs of the body form organ systems.

Question 27

Give a brief description of the following organ systems. What is/are their main functions? Where are they located in the body?

integumentary system, cardiovascular system, lymphatic and immune systems, digestive system, respiratory system, urinary system, skeletal system, muscular system, nervous system, endocrine system, reproductive system

Answer 27

The integumentary system contains skin and also includes nails, hairs, muscles, oil and sweat glands, blood vessels, and nerves. It has many homeostatic functions.

Cardiovascular System
The heart pumps blood and sends it out under pressure into the blood vessels.

Blood distributes heat produced by the muscles and transports nutrients and oxygen to the cells. It also removes their waste products.

Specialized cells in the blood are also involved in fighting infections and blood clotting.

Lymphatic and Immune Systems
The lymphatic system consists of lymphatic vessels, lymph nodes, the spleen, and other lymphatic organs.

It is involved in collecting excess tissue fluid, absorbing lipoproteins, and transporting lymph.

The immune system consists of all the cells in the body that protect us from disease.

Digestive System
The digestive system consists of the mouth, esophagus, stomach, small intestine, large intestine, and associated organs. It receives food and digests it.

Respiratory System
The respiratory system consists of the lungs and the tubes that take air to and from them. It brings oxygen into the body and removes carbon dioxide.

Urinary System
The urinary system contains the kidneys, the bladder, and the tubes that carry urine. The kidneys rid the body of metabolic wastes and help regulate the water-salt balance and acid-base balance of the blood.

Skeletal System
The bones of the skeletal system protect and move body parts. They also store minerals and produce blood cells.

Muscular System
Skeletal muscle maintains posture and accounts for the movement of the body. Muscle contractions also help to warm the body.

Cardiac muscle pumps blood.

Smooth muscle moves other substances such as urine and food.

Nervous System
The nervous system consists of the brain, spinal cord, and associated nerves. This system allows us to respond to both external and internal stimuli.

Endocrine System
The endocrine system consists of hormonal glands that secrete chemical messengers. Hormones have a wide range of effects on the body. Both the nervous and endocrine systems coordinate and regulate the functioning of the body’s other systems.

Reproductive System
The reproductive system differs between males and females, but it is responsible for the continuance of the species.

Question 28

Define: dorsal cavity and ventral cavity

Answer 28

The human body is divided into two main cavities: the ventral cavity and the dorsal cavity.
The ventral cavity later becomes the thoracic, abdominal, and pelvic cavities.

Question 29

Distinguish among the following body membranes: mucous membranes, serous membranes, synovial membranes.

Answer 29

Mucous membranes line the tubes of the digestive system.

Serous membranes line the thoracic and abdominal cavities and cover the organs they contain.

Synovial membranes line joint cavities, and meninges line the dorsal cavity.

Question 30

Define homeostasis.

Answer 30

Homeostasis is the body’s ability to maintain a relative constancy of its internal environment by adjusting its physiological processes.

Question 31

Distinguish between blood and interstitial fluid. What are their functions?

Answer 31

The internal environment has two parts: blood and interstitial fluid.

Blood delivers oxygen and nutrients to the tissues and carries carbon dioxide and wastes away.

Interstitial fluid is the medium through which substances are exchanged between cells and blood.

Question 32

Distinguish between negative feedback and positive feedback. Give examples of each.

Answer 32

• Negative feedback is the primary homeostatic mechanism that keeps a variable (like the blood glucose level) close to a particular value.

It has at least two components: a sensor and a control center.

Ex.
A home heating system is often used to illustrate how a more complicated negative feedback mechanism works. The thermostat determines the set point and contains a thermometer, the sensor that detects when the room temperature is above or below the set point. It also contains the control center that turns the furnace on and off.

• Positive feedback brings about an increasing change in the same direction. One example of positive feedback is the release of oxytocin during childbirth. This hormone stimulates uterine contraction, which continues until birth occurs. This hormone also stimulates milk letdown.

The blood clotting process is also a positive feedback mechanism.