Hormonal Coordination In Humans

Question 1

What is negative feedback?

Answer 1

Negative feedback is a homeostatic mechanism.

It is the regulation of internal conditions to maintain conditions for function in response to an interanl or external change

Question 2

What are hormones?

Answer 2

Chemical messangers which ae secreted by glands into the bloodstream and transmitted to a target organ

Question 3

What is the function of thyroxine

Answer 3

Stimulates basal metabollic rate and growth

Question 4

What are the differences between the nervous system and the endocrine system?

Answer 4

The nervous system releases electrical impulses which are transmitted along neurones. Reflexes from the nervous system are rapid and automatic,they do not last long
The endocrine system releases hormones which are transmitted along the bloodstream
The hormones are secreted slowly but they are long-lasting

Question 5

Which gland detects changes in thyroxine levels in the blood?

Answer 5

Hypothalamus

Question 6

Which gland secretes TRH into the bloodstream?

Answer 6

Hypothalamus

Question 7

Which gland detects TRH levels in the blood stream?

Answer 7

Pituitary gland

Question 8

Which gland secretes TSH into the bloodstream?

Answer 8

Pituitary gland

Question 9

Which gland detects TSH levels in the bloodstream?

Answer 9

Thyroid gland

Question 10

What is the function of the thyroid gland?

Answer 10

Secretes thyroxine which stimulate basal metabolic rate and growth

Question 11

Which gland secretes thyroxine into the bloodstream?

Answer 11

Thyroid gland

Question 12

Explain how thyroxine works as a part of the negative feedback loop

Answer 12

The hypothalamus in the brain detects the low levels of thyroxine in the bloodstream. This stimulates the secretion of TRH from the hypothalamus into the bloodstream
The TRH is detected by the pituitary gland. This stimulates the secretion of TSH from the pituitary gland
The TSH is detected by the thyroid gland. This stimulates the secretion of the thyroxine hormone, increasing basal metabollic rate
When the thyroxine levels in the bloodstream rise too high, this is detected by the hypothalamus in the brain, and this inhibits the secretion of TRH from the hypothalamus into the bloodstream.
The pituitar gland detect the low levels of TRH, this inhibits the secretion of TSH from the pituitary gland into the bloodstream
Then the thyroid gland detects the low levels of TSH, this inhibits the secretion of thyroxine into the bloodstream.

This fluctuation of thyroxine secretion about the normal is the negative feedback loop

Question 13

What happens when there is a high level of the thyroxine hormone in the bloodstream

Answer 13

Negative feedback:
The hypothalamus in the brain detects the high levels of thyroxine in the bloodstream, this inhibits TRH secretion form the hypothalamus into the bloodstream

The reduced levelsof TRH are detected by the pituitary glands. This then inhibits TSH secretion from the pituitary gland into the bloodstream

The reduced levels of TSH are detected by the thyroid gland, this stimulates the thyroid to secrete less thyroxine into the blood stream, reducing basal metabollic rate

Question 14

Which gland detects levels of thyroxine in the blood stream?

Answer 14

Hypothalamus

Question 15

Which gland detects levels of TRH in the bloodstream?

Answer 15

Pituitary gland

Question 16

Which gland detects levels of TSH in the blood stream?

Answer 16

Thyroid gland

Question 17

Which gland secretes the adrenaline hormone?

Answer 17

Adrenal gland

Question 18

Which three organs does adrenaline affect?

Answer 18

1. Heart
2. Liver
3. Blood vessels

Question 19

What does the adrenaline hormone do to the heart to prepare the body for the ‘‘fight or flight’ response?

Answer 19

Adrenaline causes the heart muscle to contract and relax rapidly.

This increases blood flow around the body.

This increases oxygen and glucose supply to muscle cells.

This increases respiration which releases energy for the ‘fight or flight’ response

Question 20

What does the adrenaline hormone do to the liver to prepare the body for the ‘fight or flight’ response?

Answer 20

Adrenaline breaks down glycogen which is stored in the liver and converts it into glucose.

This increases the supply of glucose in cells whcih reacts with oxygen, thus increasing respiration in muscle cells
This releases energy for the ‘fight or flight’ response

Question 21

What does the adrenaline hormone do to the blood vessels to prepare the body for the ‘fight or flight’ response?

Answer 21

Adrenaline causes the blood vessels which supply blood to the non-vital organs to constrict and become narrower toredirect the flow of blood to the muscle cells.

This increases the flow of blood to the muscle cells.
This increases the supply of oxygen and glucose in the muscle cells, increasing respiration.
This releases energy for the ‘fight or flight’ response

Question 22

Why is it that adrenaline is not part of the negative feedback cycle?

Answer 22

Levels of adrenaline do not need to be maintained

Adrenaline is only needed in certain situations

Question 23

Name two non-vital organs

Answer 23

Small Intestine
Large Intestine

Question 24

Why is it important that adrenaline is not part of the negative feedback cycle?

Answer 24

It reduces the body’s energy consumption once the danger/stress is over and everything is normal

Question 25

**What** happens to **pupils** when **adrenaline** is **secreted** from **adrenal glands**?

Answer 25

They **dilate**

Question 26

**Why** do **pupils dilate** as an **effect** of **adrenaline** for **'fight or flight**?

Answer 26

To **allow more light** in, for **improved vision**

Question 27

**What** causes **blood glucose levels** to **increase**?

Answer 27

**Eating starchy/sugary foods**

Question 28

**What** causes **blood glucose levels** to **decrease**?

Answer 28

**Not eating** **Excercise**

Question 29

**Explain** how **insulin controls blood glucose levels** in the **body**

Answer 29

**Blood glucose levels increase** after eating **strach/sugary foods** This **triggers** the **pancreas** to **secrete insulin** into the **bloodstream** **Insulin** is **transmitted** along the **bloodstream** to the **liver** and **muscle cells** This causes the **liver** and **muscle cells** to become **more permeable** to **glucose**. The **liver** and **muscle cells** then **convert glucose** into **glycogen**, and the **glycogen** is **stored** in the **liver** This causes the **blood glucose levels** to **reduce** as the **glucose** is beign **stored** as **glycogen** in the **liver**

Question 30

**Explain** how **insulin** and **glucagon interact** in the **negative feedback cylce** to **control blood glucose levels**

Answer 30

**Blood glucose levels rise** due to **eating starchy/sugary foods** This triggers the **pancreas** to **secrete insulin** into the **blood stream** The **insulin** is **transmitted** along the **blood stream** to the **liver** and **muscle cells**. The **liver** and **muscle cells** become **more permeable** to **glucose**, then the **cells convert** the **glucose** into **glycogen**, this **reduces blood glucose levels** as the **glucose** is being **stored** in the **liver** as **glycogen**. When the **blood glucose levels reduce too low** due to **excercise** or **not eating** this **triggers** the **pancreas** to **secrete glucagon** into the **bloodstream** The **glucagon** travels along the **bloodstream** to the **liver**. This causes the **liver** to **convert** tje **glycogen** into **glucose**. This **increases blood glucose levels** as the **glucose** has been **released** into the **bloodstream**

Question 31

**Explain** what happens when **blood glucose levels** in the body are **too low**

Answer 31

**Blood glucose levels fall too low** due to **excercise** or **not eating** This **triggers** the **pancreas** to **secrete glucagon** into the **bloodstream** The **glucagon** is **transmitted** along the **bloodstream** to the **liver**. This causes the liver to **convert** the **glycogen store** into **glucose**. This **increases blood glucose levels** as the **glucose** is **released** into the **bloodstream**

Question 32

**What** are the **two types** of **diabetes**?

Answer 32

**Type 1 diabetes** **Type 2 diabetes**

Question 33

**What** is **type 1 diabetes**

Answer 33

A **disorder** when the **pancreas no longer produces** a **sufficient amount** of **insulin**. So when **blood glucose levels rise** after eating a **starchy/sugary** meal, the **pancreas** is **unable** to **produce sufficient insulin**, so people with **type 1 diabetes** often have **uncontrolled high blood glucose levels**

Question 34

Do people with **type 1 diabetes** have **high** or **low blood glucose levels**?

Answer 34

**Uncontrolled high blood glucose levels** because the **pancreas** is **unable** to **produce sufficient insulin**

Question 35

**How** is **type 1 diabetes treated**?

Answer 35

People with **type 1 diabetes** will **monitor** their **blood glucose levels** and **inject themselves** with **insulin** when their **blood glucose concentration** is **too high**, this will cause the **blood glucose levels** to **reduce**

Question 36

**What** is **type 2 diabetes**?

Answer 36

**Type 2 diabetes** is when **cells** in the body **no longer respond** to the **insulin** that is secreted from the **pancreas**. This results in **high blood glucose levels**

Question 37

**What** is a **major risk** of **type 2 diabetes**?

Answer 37

**Obesity**

Question 38

**How** is **type 2 diabetes treated**?

Answer 38

People with **type 2 diabetes** are **treated** with a **diet** containing **low levels** of **carbohydrates**. This is in efforts too **stop blood glucose levels** from **rising too high** People with **type 2 diabetes** are also encouraged to **excercise**