Homeostasis

Question 1

Factors in tissue fluid that need to be kept constant (homeostasis)

Answer 1

• Water
• Oxygen
• Carbon dioxide
• pH
• Temperature
• Nutrients
• Hormones
• Excretory waste

Question 2

The importance of maintaining constant water levels in tissue fluid

Answer 2

• Water is medium for many chemical reactions
• Prevents dehydration and death
• Important for osmoregulation and maintaining turgidity

Question 3

The importance of maintaining high oxygen levels in tissue fluid

Answer 3

• Affects the rate of cellular respiration
• and the rate of energy production

Question 4

The importance of maintaining low carbon dioxide levels in tissue fluid

Answer 4

• A waste product of cellular respiration
• it must be excreted Its presence lowers the pH (more acidic)

Question 5

The importance of maintaining homeostasis of pH levels in tissue fluid

Answer 5

Optimum levels for enzyme activity between 7,0 and 7,4 for most enzymes

Question 6

The importance of maintaining homeostasis of temperature in tissue fluid

Answer 6

Optimum temperatures required for enzyme functioning.

Question 7

The importance of maintaining nutrient levels in tissue fluid

Answer 7

• Needed for growth, repair and metabolism
• Example: glucose, amino acids and fatty acids

Question 8

The importance of maintaining low excretory waste levels in tissue fluid

Answer 8

Waste products like urea and carbon dioxide need to be continually removed as these are toxic if accumulated

Question 9

Examples of organs responsible for maintaining tissue fluid homeostasis

Answer 9

• Kidneys (osmoregulation - water and salt)
• Lungs (carbon dioxide)
• Pancreas and liver (glucose)
• Skin (thermoregulation - temperature)

Question 10

The maintaining of constant internal environment in the body

Answer 10

Homeostasis

Question 11

Negative feedback mechanism

Answer 11

• The mechanism involving the detection of a deviation from the normal state,
• resulting in a reaction that counteracts the change and returns it to normal.

Question 12

The regulation of the body temperature of an organism.

Answer 12

Thermoregulation

Question 13

ectothermic

Answer 13

The group of animals with a body temperature varying according to the environmental temperature.

Question 14

Endothermic animals

Answer 14

The group of animals maintaining their body temperature, irrespective of the environmental temperature.

Question 15

The process during which enzymes, at high temperatures, lose their shape permanently and cannot fulfill their function.

Answer 15

Denature

Question 16

The maim source of heat generation in the human body, occurring in every living cell.

Answer 16

Cellular respiration

Question 17

The loss of heat energy by the body, from a warm body to a cold environment by rays or waves.

Answer 17

Radiation

Question 18

The loss of heat by the body when the surrounding air is warmed.

Answer 18

Convection

Question 19

The loss of heat from the body when energy is transferred from warm objects to cold objects in contact with one another.

Answer 19

Conduction

Question 20

The loss of heat from the body when sweat evaporates from the surface of the body and heat is absorbed from the skin.

Answer 20

Evaporation

Question 21

Epidermis

Answer 21

• The external part of the skin, made up of layers which protects the underlying tissues.
• Cornified, granular and Malpighian layers.

Question 22

The protein found in the outer epidermal cornified layer of human skin.

Answer 22

Keratin

Question 23

The bottom layer of the epidermis, made up of living cells.

Answer 23

Malpighian layer

Question 24

Melanin

Answer 24

The pigment in the bottom layer of skin that provides protection from the harmful UV rays of the sun and gives colour to the skin.

Question 25

Example ectothermic animals

Answer 25

Fish, amphibians and reptiles

Question 26

How reptiles regulate body temperature.

Answer 26

* Colour and body orientation to the sun * Dark colours absorb more heat, * pale colours reflect the sun's rays better

Question 27

Example endothermic animals

Answer 27

birds and mammals

Question 28

Advantage of being endothermic

Answer 28

Active both in cold and warm environmental conditions

Question 29

Cornified layer of epidermis

Answer 29

* Outermost layer Dead, flattened, flaky cells * Contain keratin to protect skin from water light and infection

Question 30

Granular layer of epidermis

Answer 30

Layer under cornified layer with living cells

Question 31

Malpighian layer of epidermis

Answer 31

* Living cells that divide to replace damaged and shed layers of skin * Contain pigment melanin * Cells supplied by tissue fluid from dermis

Question 32

Dermis

Answer 32

Layer beneath epidermis that contains: * blood and lymph vessels, * nerves, * sensory organs, * hair follicles, * tiny erector muscles * and glands.

Question 33

Blood vessels in dermis

Answer 33

* able to constrict or dilate to help regulate body temperature * diameter controlled by vasomotor center in medulla oblongata

Question 34

Lymph vessels in dermis

Answer 34

* Lymph capillaries in the dermis carry excess tissue fluid with waste products away from the skin * into larger lymph vessels

Question 35

Nerves in dermis

Answer 35

* Sensor nerves conduct impulses from the skin to the CNS * Motor nerves conduct impulses from the hypothalamus to the muscles in the blood vessels * and to glands and erector muscles.

Question 36

Sensory organs in the dermis

Answer 36

* Ruffini's corpuscles detect heat * Krause's corpuscles detect cold * Pacinian corpuscles detect pressure * Meissner's corpuscles detect touch * Free nerve endings detect pain

Question 37

What is tissue fluid?

Answer 37

* Body fluid found bathing the cells * (Called blood plasma in the blood vessels) * (Called lymph when found in the lymph vessels)