B9 Coordination and response - 3 & 4

Question 1

What is a hormone?

Answer 1

A hormone is a chemical substance, produced by a gland, carried by the blood, which alters the activity of one or more specific target organs.

Question 2

What are the glands that produce hormones in animals called?

Answer 2

The glands that produce hormones in animals are known collectively as the endocrine system.

Question 3

What are examples of some of the glands of the endocrine system?

Answer 3

-Pituitary gland - brain.
-Thyroid gland produces thyroxine - throat.
-Pancreas produces insulin.
-Adrenal glands produce adrenaline.
-Testes produce testosterone in males.
-Ovaries release oestrogen in females.

Question 4

What is adrenaline?

Answer 4

Adrenaline is the hormone secreted in ‘fight or flight’ situations and its effects, limited to increased breathing and pulse rate and widened pupils.

Question 5

Where are hormones made and secreted?

Answer 5

Hormones are made and secreted by glands.

Question 6

How do hormones travel to target cells?

Answer 6

Hormones travel in the blood to target cells.

Question 7

How do hormones bring about a response?

Answer 7

Hormones bind to receptors on target cells, triggering chemical reactions in the target cells. This brings about a response.

Question 8

What are the similarities between the nervous and endocrine system?

Answer 8

They both send signals around the body to bring about a response to regulate the conditions around the body.

Question 9

What are the differences between the nervous and endocrine system?

Answer 9

The nervous system consists of nerves (neurones), the brain and the spinal cord whereas the endocrine system consists of glands.
The nervous system sends electrical impulses whereas the endocrine system sends chemical hormones.
The nervous system sends signals much quicker than the endocrine system.
The length of the effect (longevity) is very short for the nervous system as it is until the nerve impulses stop, but for the endocrine system is it much longer since it is until the hormone is broken down.

Question 10

When is adrenaline released?

Answer 10

Adrenaline is released in times of great danger or stress. - it evolved as a survival mechanism to evade dangerous situations.

Question 11

What does adrenaline bring about?

Answer 11

Adrenaline brings about several changes in the body to enable these kind of responses.

Question 12

What is adrenaline secreted from?

Answer 12

Adrenaline is secreted from the adrenal glands into the blood.

Question 13

Where are the adrenal glands?

Answer 13

The adrenal glands are positioned on top of both kidneys.

Question 14

Why is the fact that adrenaline can travel around the body in the blood useful?

Answer 14

It is very useful that adrenaline can travel around the body in the blood because it can trigger responses in lots of areas of the body simultaneously.

Question 15

What changes does it cause to happen in the body?

Answer 15

-Increasing blood glucose concentration for increased respiration in muscle cells.
-Increasing pulse rate and breathing rate so glucose and oxygen can be delivered to muscle cells, and carbon dioxide taken away, from muscle cells more quickly.
-Diverting blood flow towards muscles and way from non-essential parts of the body such as the alimentary canal; again to ensure the reactants of respiration are as available as possible.
-Dilating pupils to allow as much light as possible to reach the retina so you can be more receptive to changes in the environment - so more information can be sen to the brain.

Question 16

What happens once the adrenaline is no longer needed?

Answer 16

When the adrenaline is no longer needed, it is broken down by the liver.

Question 17

Why does an increased heart rate cause an increase in the delivery of glucose and oxygen?

Answer 17

As the heart rate increases, the heart beats faster to pump more oxygen and glucose to the muscle cells. At the same time, more carbon dioxide is taken away from muscle cells more quickly.

Question 18

Why do muscle cells need oxygen and glucose?

Answer 18

The muscle cells need oxygen and glucose to break down the glucose to use is as a fuel - fight or flight.

Question 19

What are other effects of adrenaline?

Answer 19

-Increasing the concentration of glucose in the blood which helps to deliver more important glucose to muscles for respiration.
-Increasing heart rate to ensure that all muscles are well prepared for high levels of activity in a flight or fight situation.

Question 20

How does adrenaline increase blood glucose concentration?

Answer 20

Adrenaline raises blood glucose levels by stimulating your liver to release glucose.

Question 21

What organ stores and produces glucose?

Answer 21

The liver both stores and produces sugar. The liver helps to keep your circulating blood sugar levels and other body fuels steady and constant.

Question 22

What is homeostasis?

Answer 22

Homeostasis is the maintenance of a constant internal environment.

Question 23

What does homeostasis mean?

Answer 23

Homeostasis means that internal conditions within the body need to be kept within set limits in order to ensure that reactions in body cells can function and therefore the organism as a whole can live.

Question 24

What are examples of the internal conditions homeostasis controls?

Answer 24

Homeostasis controls internal conditions such as:
-temperature
-blood pressure
-water concentration
-glucose concentration

Question 25

What happens when an internal condition deviates far away from the normal?

Answer 25

When an internal conditions deviates far away from the normal and is not brought back within set limits, the body will not function properly and the eventual consequence without medical intervention is death.

Question 26

When is insulin secreted and from where?

Answer 26

Insulin is secreted from the endocrine cells of the pancreas into the blood when the blood glucose levels are high. It then travels in the blood to target organs such as the liver and muscles. - tends to be after a meal.

Question 27

Why is glucose needed?

Answer 27

Glucose is needed for respiration to provide energy for our body processes.

Question 28

What happens when glucose levels increase?

Answer 28

When glucose levels increase too high, it can affect osmoregulation in the body and can damage blood vessels.
-when glucose levels increase too much, it decreases the conc of water in blood and causes water to move out of the cells and into the blood by osmosis. The cells become dehydrated and shrivelled.

Question 29

When happens in the kidneys if the glucose levels in the blood are too high?

Answer 29

The kidneys can only cope with a certain level of glucose in the blood. If the level gets too high, glucose gets excreted and is lost in the urine.
However, this is avoided by insulin converting excess glucose into glycogen.

Question 30

What does insulin do?

Answer 30

Insulin helps to lower the blood glucose levels when they are too high by instructing the liver to temporarily convert excess glucose into glycogen in the liver and muscles (target cells). It is converted back to glucose later when blood glucose levels have dipped due to respiration in all levels.

Question 31

What is negative feedback?

Answer 31

Negative feedback occurs when conditions change from the optimum level and it returns conditions to this level.

Question 32

How does negative feedback work?

Answer 32

-if the level of something rises, control systems are switched on to reduce it again
-if the level of something falls, control systems are switched on to raise it again

Question 33

How are negative feedback mechanisms?

Answer 33

Negative feedback are mechanisms as they are usually a continuous cycle of bringing levels down and then bringing them back up so that overall, they stay within a narrow range of what is considered ‘normal’.

Question 34

By what negative feedback mechanism is blood glucose levels controlled by?

Answer 34

Blood glucose levels re controlled by a negative feedback mechanism involving the production of two hormones - insulin and glucagon.

Question 35

Where are insulin and glucagon made?

Answer 35

In the pancreas.

Question 36

When is insulin produced?

Answer 36

Insulin is produced when blood glucose rises and stimulates liver and muscle cells to convert excess glucose into glycogen to be stored.

Question 37

When is glucagon produced?

Answer 37

Glucagon is produced when blood glucose falls and stimulates liver and muscle cells to convert stored glycogen into glucose to be released into the blood.

Question 38

What is thermoregulation?

Answer 38

Thermoregulation is the control of body temperature. It is a homeostatic mechanism.
-37°C is the temperature the enzymes in the human body work best.

Question 39

What happens if the body temperature increases over 37°C?

Answer 39

If it increases over this temp, enzymes will denature and become less effective at catalysing reactions such as respiration.

Question 40

What is regulation controlled by?

Answer 40

Regulation is controlled by the brain.

Question 41

What does the brain contain?

Answer 41

The brain contains receptors sensitive to the temperature of the blood.

Question 42

What does the skin have?

Answer 42

The skin also has temperature receptors and sends nervous impulses to the brain via sensory neurones.

Question 43

How does the brain respond to an impulse from the skin receptors?

Answer 43

the brain responds to this information by sending nerve impulses to effectors in the skin to maintain the temperature within a narrow range of the optimum.

Question 44

What acts as a layer of insulation?

Answer 44

Fatty tissue under the dermis acts as a layer of insulation to prevent too much body heat being lost through the skin.

Question 45

What are the homeostatic responses when we are hot?

Answer 45

When we are hot:
-Sweat is secreted by sweat glands. This cools skin by evaporation. Heat energy from the body is lost as liquid water in sweat becomes water vapour (change in state).
-Hairs lie flat against the skin, allowing air to freely circulate. This increases heat transfer to environment by radiation.

Question 46

What are the homeostatic responses when we are cold?

Answer 46

When we are cold:
-Skeletal muscles contract rapidly and we shiver. These involuntary muscle contractions need energy from respiration and some of this is released as heat.
-Erect hairs (contracted) trap a layer of air around the skin which acts as an insulator, preventing heat loss by radiation.

Question 47

What is vasodilation?

Answer 47

Vasodilation happens when the body is too hot. The blood is directed towards the surface of the skin to increase heat radiation into the environment.
-Artery that sends blood to the skin surfaces dilates

Question 48

What is vasoconstriction?

Answer 48

Vasoconstriction happens when the body is too cold. The blood is redirected away from the skin surface to reduce heat radiation into the environment.
-Artery that sends blood to the skin surface constricts.