Life Science - Homeostasis Thermoregulation

What is homeostasis in relation to thermoregulation?

The body's ability to maintain a stable internal temperature through negative feedback mechanisms.

Hyperthermia

Results when the body temperature rises and remains above 36,9°C, for a long period

Hypothermia

Results when the body temperature drops and remains below 36,9°C for a long period.

How does negative feedback help in thermoregulation?

Negative feedback counteracts temperature changes by activating mechanisms to restore the body's normal temperature.

What are the four ways the body gains or loses heat?

Conduction, Convection, Radiation, and Evaporation.

What is conduction?

the direct transfer of heat through contact with a hot or cold surface.

What is radiation?

energy that is radiated or transmitted through space in the form of rays or waves

What is evaporation?

heat release by transforming a liquid present on the skins surface into a vapour

How does sweating help in cooling the body?

Heat from blood warms sweat changing it from a liquid to a gas. Warm sweat evaporates and is replaced by cooler air resulting in a drop in temperature. This is called Evaporative cooling

evaporative cooling

As a liquid evaporates, its remaining surface cools

What is convection?

heat transfer through the movement of air or fluid, creating a convection current.

How does convection cool the body?

Warm air near the skin rises, and cooler, denser air settles on the skin. This continuous air movement helps cool the body.

Why is it important for the body to regulate its temperature?

To ensure for the bodies enzymes to work at their optimum level

What is the body's normal temperature

37 degrees Celsius

What happens to enzymes at very low temperatures?

Enzymes become inactive, slowing down metabolic reactions significantly.

What happens to enzymes at very high temperatures?

They become denatured

What happens after denatured enzymes

they lose their shape and stop working, which can lead to cell deat

What is the main organ responsible for thermoregulation?

The skin.

What structures in the skin are important for thermoregulation?

Thermoreceptors, sweat glands, blood vessels, and adipose (fat) tissue.

adipose tissue

Tissue that stores fat.

What are the two main layers of the skin?

1. Epidermis

2. Dermis

How many layers does the epidermis have? And what are they?

4,The horny layer(dead cells) ,Non-ganular layer, Granular layer, malpighian layer (gives skin color)

What are the main functions of the epidermis?

It protects against damage, water loss, heat loss, bacterial invasion, and excessive UV exposure.

What is the function of the germinative layer?

It continuously divides by mitosis to produce new skin cells, which move to the surface, die, and form a protective covering.

What type of cells make up the uppermost part of the epidermis?

Dead cells.

What are melanocytes?

pigment-producing cells

Where are melanocytes found?

germinative layer of the epidermis.

What pigment do melanocytes produce?

melanin

What is the function of the melanocyte pigmentation?

protects the skin from UV radiation

How does UV exposure affect melanin production?

Increased UV exposure leads to more melanin production, causing the skin to darken.

What do sebaceous (oil) glands produce?

sebum

What are the two main functions of sebum?

It prevents the skin from drying out and keeps it supple.

What are hair follicles?

Deep invaginations in the germinative layer where hair grows.

Invagination

the folding in of a membrane or layer of tissue so that an outer surface becomes an inner surface

Where does hair growth occur in the follicle?

At the papilla, where cells divide by mitosis to form the hair shaft.

How does sebum affect hair?

It coats the hair to prevent it from drying out or splitting.

What is the dermis composed of?

Loose connective tissue that attaches the skin to the muscles below.

What substances do sweat glands excrete?

Excess water, urea, and salts.

How do sweat glands remove metabolic waste from the body?

The waste is carried by the blood to the sweat glands, then excreted through a sweat duct and out through a sweat pore onto the skin's surface.

How does sweat contribute to thermoregulation?

The evaporation of sweat helps cool the body by removing heat from the skin.

What role do blood vessels in the dermis play in thermoregulation?

Blood vessels constrict (narrow) to retain heat and dilate (widen) to release heat.

What is the function of nerves in the dermis?

Nerves relay sensory information from receptors to the CNS and send signals from the CNS to effectors like sweat glands.

What do thermoreceptors do?

detect changes in temperature

What are erector muscles, and what do they do?

They are small muscles attached to hair follicles that cause hair to stand up (when cold or frightened) or lay flat (when warm).

How does erect hair help animals in cold environments?

It traps air, which acts as an insulating layer, reducing heat loss.

What is the hypodermis, and what is it made of?

The hypodermis is the layer below the skin, made up of adipose (fatty) tissue.

How does adipose tissue help with thermoregulation?

Fat is a good insulator, reducing heat loss and heat gain.

What detects rising body temperature in the skin?

Ruffini's bodies, which transform the heat stimulus into a nerve impulse.

How is the hypothalamus stimulated to regulate body temperature?

1. Sensory neurons send impulses from thermoreceptors in the skin.

2. Warm blood flowing through the hypothalamus directly stimulates it.

How does the hypothalamus cool the body?

Vasodilation and Sweating

How does vasodilation occur and help with heat loss?

The involuntary muscles in blood vessels dilate (widen), allowing more blood near the skin surface. This increases heat loss via radiation and convection.

How does thyroxin production change when the body is hot?

Thyroxin production decreases, reducing cell metabolism and heat production.

How do muscles respond to rising body temperature?

Muscle tone decreases, making muscles more relaxed, which reduces heat production.

What are some behavioural responses to high body temperature?

Removing clothing Drinking cool beverages Moving to a cooler environment

What detects decreasing body temperature in the skin?

Krause bodies, which transform the cold stimulus into a nerve impulse.

How is the hypothalamus stimulated when the body is cold?

Sensory neurons send impulses from thermoreceptors in the skin. Cooler blood flowing through the hypothalamus directly stimulates it.

How does the hypothalamus reduce heat loss? (3)

Vasoconstriction Blood is rerouted to deeper blood vessels in the hypodermis, where fat insulation prevents further heat loss. Sweat glands become less active, leading to less sweat production. This reduces evaporative cooling, helping the body retain heat.

Vasorestriction

Involuntary muscles in blood vessels constrict, reducing blood flow near the skin. This decreases heat loss via radiation.

How does thyroxin production change when the body is cold?

Thyroxin production increases, raising cell metabolism and heat production.

How do muscles respond to cold temperatures? (2)

Muscle tone increases, making muscles more active. Shivering occurs, which generates additional heat.

What are some behavioural responses to low body temperature?

Putting on more clothing Moving to a warmer environment Drinking warm beverages