B3.3 Maintaining internal environments Flashcards
Define homeostasis.
The maintenance of a stable internal environment in the body despite fluctuations in the internal and external conditions.
State three conditions which need to be controlled within the body.
- Temperature
- Water levels
- Blood glucose concentration
- Blood solute levels
- Blood pH
Why does temperature need to be controlled?
To provide a suitable environment for enzymes so that they can work fatest at their optimum temperature.
State two processes involving the skin which cool the body down.
- Sweating - water evaporates from the skin surface resulting in increased energy transfer away from the body
- Vasodilation - Allow blood to flow closer to the surface of the skin allowing more heat to be released from the body by convection and conduction
- Hairs lie flat - preventing heat from being trapped by the layer of still air between the hair. These flat hairs increase the flow of air next to the skin increasing heat loss by convection.
Describe the process of vasodilation.
- Thermoreceptors in the hypothalamus detect a rise in core body temperature
- Neural impulse sents to the blood vessels supplying the capillaries at the skin skin surface to dilate (smooth muscle in vessels = effector = relax)
- More blood flows closer to the skin surface where energy can be released by conduction and convection.
State three processes that work to keep the body warm.
- Vasoconstriction
- Shivering
- Erections of hairs on the skin
Describe the process of vasoconstriction.
- Thermoreceptors in the hypothalamus detect a drop in core body temperature
- Neural impulse sents to the blood vessels supplying the capillaries at the skin skin surface to constrict (smooth muscle in vessels = effector = contract)
- Less blood flows closer to the skin surface where energy can be lostto the surroundings by conduction and convection.
What happens when you get too hot?
- Body hairs lie flat โ Hair erector muscle relaxes, hairs lie flat preventing an insulating layer of air forming around body, allowing heat loss to environment by radiation
- Vasodilation - Blood vessels in the skin get wider allowing a larger volume of blood to flow near the skin surface, transferring heat to the environment by radiation. This cools the body down.
- Sweating - Production of sweat from sweat glands. As the sweat evaporates it transfers heat away from the body. Sweating also makes you lose water and mineral ions โ you need to take in more liquid to replace the lost water and mineral ions.
- Factors affecting evaporation โ Temperature, humidity, wind speed, surface area exposed
- What else โ Remove extra layers of clothes, drink to replace water loss through sweating
What happens when you get too cold
- Vasoconstriction - Blood vessels supplying the skin capillaries get narrower caused by contraction of the muscular wall of the blood vessels. This reduces the volume of blood flowing near the skin surface, and reduces the amount of heat lost from the body, causes pale appearance.
- Goosebumps โ Hair erector muscles contract, hair stands up trapping a layer of air close to the skin. Decreases heat loss to the environment by radiation.
- No sweat โ The sweat glands stop producing sweat.
- Shivering - When core body temperature drops, muscles begin to twitch involuntarily. Rapid and contraction and relaxation of the muscles requires respiration. Respiration releases energy warming body
- What else โ Movement/exercise to warm-up, put more clothes on.
Complete the diagram.
- Fat layer - Helps insulate the body, provides storage area for energy, helps protect internal structures.
- Skin Receptors - Respond to stimuli, send information to the brain
- Blood capillary - Vessels supplying dilate when hot: increased blood flow at skin surface = more heat loss by radiation. Constrict when cold: decreased blood flow at skin surface = less heat loss by radiation
- Hair Erector muscle - Relax when hot = hairs lie flat. Contract when cold = hairs stand up
- Sweat pore - Sweat evaporates when hot = cooling
- Hair - Lies flat when hot = less air trapped so more heat loss by radiation. Stand up when cold = air trapped at skin surface so less heat loss by radiation
- Epidermis - waterproof barrier, protection from microbes etc
- Dermis - connective tissue , cushions the body from stress and strain
- Sweat gland - Produces sweat when hot to allow cooling by evaporation
Why is it important to control blood glucose levels?
- Glucose is the energy source used predominantly in respiration to transfer energy to ATP used by cells.
- If levels rise too high this can damage blood vessels and nerves, increasing the risk of heart disease and stroke, kidney disease, vision problems, and nerve problems. In severe cases of uncontrolled blood sugar levels this can cause diabetic ketoacidosis (DKA), which can result in death.
- If lows fall to low this can prevent cells from respiring effectively.
State two effects caused by insulin secretion.
- More glucose is taken up by cells decreasing blood glucose levels
- Glucose is converted to glycogen decreasing blood glucose levels
What does the secretion of glucogon cause?
Glucogon secretions cause glycogen to be broken down into glucose to raise the blood glucose concentration.
What is the difference between type 1 and type 2 diabetes?
- Type 1 diabetes is when the pancreas is unable to produce (or does not produce enough) insulin.
- Type 2 diabetes is where the body no longer responds to insulin.
How can type 1 diabetes be treated?
- Insulin injections
- Insulin pump