YR11 - Topic Test 2 - Adaptations, Homeostasis Flashcards
Define Adaptation
Any heritable trait that helps an organism, such as a plant or animal, survive and reproduce in its environment
Examples of Physical/Structural Adaptations
Beaks of a bird Skin/Fur (Camoflague) Big ears to cool down Thick fur to keep warm Small ear to reduce heat loss Big eyes to see in the dark
Definition and examples of structural adaptations
Physical features of an organism like the bill on a bird or the fur on a bear etc.
Definition and examples of behavioural adaptations
Things organisms do to survive. The actions they do. For example, bird calls and migration
Definition and examples of physiological adaptations
Internal systematic responses to external stimuli in order to help an organism maintain homeostasis (normal).
Some examples include temperature regulation, the release of toxins or poisons, releasing antifreeze proteins to avoid freezing in cold environments. camouflage etc.
Nervous and Endocrine system differences
Nervous System:
- Electrical impulses are the messengers in the nervous system
- Brain and the spinal cord are involved in the nervous system
- Nerve impulses are transmitted through neurons
Endocrine System:
- Hormones are the chemical messengers in the endocrine system that target cells through the bloodstream
- Glands and organs like thyroid, pituitary glands and reproductive organs (ovaries and testes) are involved in the endocrine system.
- Hormones are transmitted through blood vessels.
Define Homeostasis
Homeostasis is the ability to maintain a relatively stable internal state that persists despite changes in the world outside
Purpose of Homeostasis
To maintain a normal balance within the body regarding its temperature, salt concentration, water concentration, and food intake.
Thermoregulation Stimulus-Response Model
TOO HOT
Stimulus: too hot
Receptor: thermoreceptors
Control Center: Hypothalamus
Effector: Sweat glands, Diaphragm, Muscles around blood vessels dilate (piloerection)
Response: Sweat, Breathing, Vasodilation (to increase blood flow to extremities).
TOO COLD
Stimulus: too cold
Receptor: thermoreceptor
Control Centre: Hypothalamus
Effector: skeletal muscles, hair follicles go rigid, muscles around blood vessels (piloerection)
Response: shivering to increase heat, goosebumps, vasoconstriction (decrease blood flow)
Blood Glucose Regulation Stimulus-Response Model
HGL
Stimulus: high glucose in the blood (from food)
Receptor: pancreas, beta cells
Signal: Insulin - the hormone that travels to send a message
Effector: liver, muscles, adipose tissue (take up glucose and store in their cells as glycogen
Response: to reduce blood glucose by taking it into cells
LGL:
Stimulus: fasting blood glucose is too low
Receptor: pancreas, alpha cells
Effector: liver, muscles and adipose tissue
Response: release glucose from glycogen
Both Negative Feedback
Osmoregulation (Water/Salt Balance) Stimulus-Response Model
INCREASE IN WATER/SALT
Stimulus: Increase of water (e.g. drinking water)
Receptors: Baroreceptors and Osmoreceptors
Control Center: Pituitary Gland —> Hypothalamus
Effector: Kidney
Response: Water released —> Peeing
DECREASE IN WATER/SALT
Stimulus: A drop in the level of water
Receptors: Baroreceptors and Osmoreceptors
Control Center: Pituitary Gland —> Hypothalamus
Effector: Kidney
Response: Reabsorb water in kidney, urine is more concentrated
Both of these are negative feedback models as the result is they return back to the body’s normal state (homeostasis).
Define Endothermic
any process which requires or absorbs energy from its surroundings, usually in the form of heat
Can produce it’s own body heat
Define Ectothermic and examples
Any animal whose regulation of body temperature depends on external sources, such as sunlight or a heated rock surface. The ectotherms include the fishes, amphibians, reptiles, and invertebrates.
They can’t produce their own heat
Define Negative Feedback
A reaction that causes a decrease in function. It occurs in response to some kind of stimulus.
Define Positive Feedback
Opposite of negative feedback
It encourages a physiological process or amplifies the action of a system. Positive feedback is a cyclic process that can continue to amplify your body’s response to a stimulus until a negative feedback response takes over
Define Hormones
A hormone is any member of a class of signalling molecules, produced by glands in multicellular organisms, that are transported by the circulatory system to target distant organs to regulate physiology and behaviour
Define Osmoregulation
Osmoregulation is the process of maintaining salt and water balance across membranes within the body.
Define Thermoregulation
The ability of an organism to keep its body temperature within certain boundaries, even when the surrounding temperature is very different.
How do plants adapt to their environment
They will often move towards the sunlight and will often adapt according to the season. E.g. Winter, Summer. Some plants move every day. They turn their leaves toward the Sun. Sunflower plants turn toward the Sun. They do this to catch as much sunlight as possible.
Desert Plant Adaptation
Desert plants have plenty of sunlight. But they receive very little water. When it does rain, they soak up as much water as they can. Their roots are often very close to the surface of the soil or sand. They are ready and waiting to catch any drop of water that falls.
Their next challenge is to hang onto the water. Desert plants have a thick, waxy surface. They have spikes instead of leaves. This stops a lot of water from being lost across their outside surface.
Rainforest Plant Adaptation
Rainforests are found in hot, rainy regions of the world. They have a lot of sunlight and a lot of rain. Thousands of plant species grow here. They all compete for light and minerals. Rainforest trees grow very fast and extremely tall. Some stand over 150 feet (46 meters). The tallest trees get the most sunlight. In this way, they compete with each other for survival.
How do humans regulate water balance?
Through the kidneys. The kidneys can adjust the concentration of the urine to reflect the body’s water needs, conserving water if the body is dehydrated or making urine more dilute to expel excess water when necessary. ADH is a hormone that helps the body to retain water by increasing water reabsorption by the kidneys.
What is the body’s response to low water levels?
When the body is low in water, the pituitary gland secretes vasopressin or ADH into the bloodstream. Vasopressin/ADH stimulates the kidneys to conserve water and excrete less urine.
Reasonable range of BGL (blood glucose levels)
between 4.0–7.8mmol/L.
what organs are involved in regulating blood glucose levels
Pancreas and liver
How do organisms respond to changes in their environment?
As a group – adaptations
Individual – regulation (internal) in changes to their (external)
What organ is involved in regulating temperature in the body?
Hypothalamus
What organs are involved in regulating water balance in the body?
Kidney
The signal is sent to brain
Major hormones
ADH, Insulin and Glucagon
What is ADH
ADH is also called arginine vasopressin. It’s a hormone made by the hypothalamus in the brain and stored in the pituitary gland. It tells your kidneys how much water to conserve. ADH constantly regulates and balances the amount of water in your blood.
What is insulin
Insulin helps control blood glucose levels by signalling the liver and muscle and fat cells to take in glucose from the blood. Insulin, therefore, helps cells to take in glucose to be used for energy. If the body has sufficient energy, insulin signals the liver to take up glucose and store it as glycogen.
Glucagon function
Glucagon’s role in the body is to prevent blood glucose levels dropping too low. To do this, it acts on the liver in several ways: It stimulates the conversion of stored glycogen (stored in the liver) to glucose, which can be released into the bloodstream.
