Homeostasis Flashcards
Factors in tissue fluid that need to be kept constant (homeostasis)
- Water
- Oxygen
- Carbon dioxide
- pH
- Temperature
- Nutrients
- Hormones
- Excretory waste
What is tissue fluid?
- Body fluid found bathing the cells
- (Called blood plasma in the blood vessels)
- (Called lymph when found in the lymph vessels)
The importance of maintaining constant water levels in tissue fluid
- Water is medium for many chemical reactions
- Prevents dehydration and death
- Important for osmoregulation and maintaining turgidity
The importance of maintaining high oxygen levels in tissue fluid
- Affects the rate of cellular respiration
- and the rate of energy production
The importance of maintaining low carbon dioxide levels in tissue fluid
- A waste product of cellular respiration
- it must be excreted Its presence lowers the pH (more acidic)
The importance of maintaining homeostasis of pH levels in tissue fluid
Optimum levels for enzyme activity between 7,0 and 7,4 for most enzymes
The importance of maintaining homeostasis of temperature in tissue fluid
Optimum temperatures required for enzyme functioning.
The importance of maintaining nutrient levels in tissue fluid
- Needed for growth, repair and metabolism
- Example: glucose, amino acids and fatty acids
The importance of maintaining low excretory waste levels in tissue fluid
Waste products like urea and carbon dioxide need to be continually removed as these are toxic if accumulated
Examples of organs responsible for maintaining tissue fluid homeostasis
- Kidneys (osmoregulation - water and salt)
- Lungs (carbon dioxide)
- Pancreas and liver (glucose)
- Skin (thermoregulation - temperature)
The maintaining of constant internal environment in the body
Homeostasis
Negative feedback mechanism
- 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.
The regulation of the body temperature of an organism.
Thermoregulation
ectothermic
The group of animals with a body temperature varying according to the environmental temperature.
Endothermic animals
The group of animals maintaining their body temperature, irrespective of the environmental temperature.
The process during which enzymes, at high temperatures, lose their shape permanently and cannot fulfill their function.
Denature
The maim source of heat generation in the human body, occurring in every living cell.
Cellular respiration
The loss of heat energy by the body, from a warm body to a cold environment by rays or waves.
Radiation
The loss of heat by the body when the surrounding air is warmed.
Convection
The loss of heat from the body when energy is transferred from warm objects to cold objects in contact with one another.
Conduction
The loss of heat from the body when sweat evaporates from the surface of the body and heat is absorbed from the skin.
Evaporation
Epidermis
- The external part of the skin, made up of layers which protects the underlying tissues.
- Cornified, granular and Malpighian layers.
The protein found in the outer epidermal cornified layer of human skin.
Keratin
The bottom layer of the epidermis, made up of living cells.
Malpighian layer
Melanin
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.
Example ectothermic animals
Fish, amphibians and reptiles
How reptiles regulate body temperature.
- Colour and body orientation to the sun
- Dark colours absorb more heat,
- pale colours reflect the sun’s rays better
Example endothermic animals
birds and mammals
Advantage of being endothermic
Active both in cold and warm environmental conditions
Cornified layer of epidermis
- Outermost layer Dead, flattened, flaky cells
- Contain keratin to protect skin from water light and infection
Granular layer of epidermis
Layer under cornified layer with living cells
Malpighian layer of epidermis
- Living cells that divide to replace damaged and shed layers of skin
- Contain pigment melanin
- Cells supplied by tissue fluid from dermis
Dermis
Layer beneath epidermis that contains:
- blood and lymph vessels,
- nerves,
- sensory organs,
- hair follicles,
- tiny erector muscles
- and glands.
Blood vessels in dermis
- able to constrict or dilate to help regulate body temperature
- diameter controlled by vasomotor center in medulla oblongata
Lymph vessels in dermis
- Lymph capillaries in the dermis carry excess tissue fluid with waste products away from the skin
- into larger lymph vessels
Nerves in dermis
- 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.
Sensory organs in the dermis
- Ruffini’s corpuscles detect heat
- Krause’s corpuscles detect cold
- Pacinian corpuscles detect pressure
- Meissner’s corpuscles detect touch
- Free nerve endings detect pain
