non-infectious disease and disorders - homeostasis

Question 1

How is an organism’s internal environment maintained in response to a changing external environment?

Answer 1

structural

physiological

behavioural

homeostasis

Question 2

positive feedback loops

Answer 2

in a positive feedback loop the stimulus is increased by a receptor - e.g. expansions of the uterus during birth when the uterine contractions cause the uterus to stretch

Question 3

negative feedback loops

Answer 3

negative feedback reverses the stimulus, both hormonal and nervous system are responsible for maintaining homeostasis

Question 4

homeostasis

Answer 4

the ability of organisms to maintain a constant internal environment despite external conditions

Question 5

internal environment

Answer 5

A term describing the fluid surrounding a cell within a multicellular organism

Question 6

Stimulus response model

Answer 6

A system in which a stimulus is detected by a receptor, which communicates with an effector to bring about a response.

Question 7

thermoregulation

Answer 7

If the temperature rises or falls, physiological (having to do with the functioning of the body) and behavioural negative feedback mechanisms return the body temperature to 36.7°C.

Question 8

glucose control

Answer 8

Insulin stimulates the liver to absorb glucose from the blood (and thereby lowers blood glucose concentration) and store it as glycogen. Glucagon stimulates the liver to convert stored glycogen to glucose and release it into the blood, increasing blood glucose concentration.

Question 9

behavioural adaptation

Answer 9

the organism moves or changes its behaviour.

Question 10

physiological adaptation

Answer 10

to do with the organism’s body composition or structure.

Question 11

structural adaptation

Answer 11

these are internal responses by the body to external changes or stimuli.

Question 12

surface area to volume ratio

Answer 12

Smaller organisms have a
larger surface area compared to their volume.

Larger organisms have a
small surface area compared to their volumes.

A large organism is more effective at thermoregulation as is loses less heat to its environment.

A small organism is more affected by temperature changes as it has a larger surface area compared to its volume.

Question 13

Endocrine gland

Answer 13

A gland that releases a hormone internally.

Question 14

gland

Answer 14

An organ that secretes a specific hormone into the blood.

Question 15

hormone

Answer 15

A chemical messenger released by a gland that has a specific target. Travel via the bloodstream. The act on enzymes in the target cells.

Question 16

target organ

Answer 16

Organs with receptors for the specific hormone.

Question 17

Pituitary gland

Answer 17

Often termed the master gland it can stimulate other glands to release their hormones.

Question 18

Thyroid gland

Answer 18

Regulates metabolic rate to control temperature. Thyroxine.

Question 19

Adrenal gland:

Answer 19

Adrenaline is released that impacts on blood pressure and the heart.

Aldosterone controls the absorption of salts from the kidneys.

Question 20

pancreas

Answer 20

releases insulin and glucagon the controls blood glucose levels.

Question 21

CNS (Central nervous system)

Answer 21

Made up of the brain and spinal cord

Question 22

CNS (Central nervous system)

Answer 22

Made up of the brain and spinal cord

Question 23

PNS (Peripheral nervous system)

Answer 23

Made of peripheral nerves which link the CNS to the body’s receptors and effectors

Question 24

sensory neurons and motor neurons

Answer 24

Sensory neuron receives a stimulus (sound, smell, visual signal, etc)

The message is sent via an electrochemical impulse along a sensory neuron to the brain

The brain then interprets the signal and sends a message via motor neurons to the body response can be made.

Question 25

structural adaptations to water loss (plants)

Answer 25

Reduced surface areas of leaves to reduce water loss. Tiny hairs on surface of the leaf to reflect sunlight and to trap water closer to the surface of the leaf and reduce transpiration. Reduced numbers of stomates. Shiny/waxy cuticles on the leaf surface.

Question 26

Changes to the orientation of leaves

Answer 26

Some plants will reduce exposure to sunlight during the hottest part of the day by changing the orientation of the leaves. Some plants will curl their leaves to create a cooler interior surface and reduce water loss through transpiration.

Question 27

Changes to stomatal opening

Answer 27

By changing the amount of water in the guard cells around a leaf plants can reduce water loss through transpiration. Closing the guard cells reduces water loss by transpiration. To do this the guard cells will lose water causing them to become limp.