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Flashcards in Hormones/Signal Transduction Deck (64)
1

What two hormones does the pancreas produce?

Insulin and Glucagon

2

What is the role of insulin and glucagon

Control glucose in the blood

3

What does insulin control

Insulin is produced when blood glucose levels needs decreasing

4

What does glucagon control

Glucagon acts if there is too little glucose in the body

5

Where is insulin produced??

Beta cells of the pancreas

6

Where is glucagon produced??

Alpha cells of the pancreas

7

Explain negative feedback if there is an increase in blood glucose

Stimulus- Increase in blood glucose
Receptor-Chemorecptor
Control Centre-Pancreas
Effector- Pacreatic beta cells will release insulin
Response-Liver and muscle cells uptake glucose and store as glycogen
Feedback- Blood sugar levels decrease

8

Explain negative feedback in regards to, too little glucose in the blood

Stimulus- decrease in blood glucose
Receptor-Chemorecptor
Control Centre-Pancreas
Effector- Pacreatic alpha cells will release glucagon
Response-Liver and muscle cells will break down glycogen and release as glucose
Feedback- Blood sugar levels increase

9

Explain how insulin promotes the uptake of glucose

Changes the permeablity of the cell membrane to glucose

10

Why do cells need to communicate

Control and regulation of systems

11

What are signalling molecules also known as??

Ligands

12

What are receptors and hormones

Specific

13

What are the three types of signals??

Autocrine signals
Paracrine Signals
Endocrine Signals

14

Define Autocrine Signals

A cell secretes a hormone into extracellular fluid and binds to its own receptors

15

Define Paracrine Signals

Signals being released by cells into extracellualr medium acts on nearby target cells, so this type of signal is a local signal.

16

Define Endocrine Signals

Signals that are produced in the endocrine gland are secreted in the blood stream, therefore distributed throughout the whole body, but only stimulate those with specific receptors

17

Defintion for Hormone

An organic molecule produced in a cell, either acting within the cell or diffusing or being transported to other cell. Hormones travel via extracellular fluid and act on specific target cells.

18

Where do hormones usually travel

In the blood stream of tissue fluid

19

What are the three different classification of hormones?

-Steroid
-Protein/peptide
-Amino acid derivative

20

Explain steroid hormones

-Tend to have a long life span
-Created on demand from precursors in the cell
-Made from chloesterol therefore lipophilic and hydrophobic
-Steroids pass through the cell membrane via simple diffusion
-Need a carrier protein when travelling through blood

21

Example of a steroid hormone

testoesterone

22

Explain Protein/Peptide Hormones

-Made in advance and stored in cells secretory vesciles
-Cannot pass through the membrane so they leave via exocytosis
-Short life span
- They are hydrophilic and can easily travel through the blood stream but need assistance when passing through the membrane

23

example of protein/peptide hormones

Adrenaline

24

Explain Amino Acid Dervative Hormones

-Small molcules that have the same structure as an amino acid
- Made in advance and stored in the secretory vescilces, leave via exocytosis.
-Short Life span
-Water soluble so they can travel through the blood stream easily but need assitance when passing through the cell membrane

25

Are hormones slow or fast

Slow

26

Do they work for a long period or time or short?

Generally long

27

Where are steriod receptors in regards to the cell?

Lipid based hormones are able to pass through the membrane easily and therefore their receptor is located on the inside of the cell in the cytosol.

28

Where are the peptide and amino hormones located?

-Situated on the outside of the cell.
-This is due to not being able to pass through the membrane
-The receptors then activate a protein on the inside of the membrane

29

Define Signal Transdution

Refers to the cascade of events originating outside the cell in leading to a specific cellular response. This is the process in which a cell converts one kind of kind into another by a series of relay molecules.

30

Explain the steps in signal transduction

-Signal is recieved
-Signal is amplified
-Transduction
-Response
-Feedback (possible)

31

What is the first messenger

The extracellular molecule that binds to the receptor is he first messenger.

32

What is the second messenger?

Molecules that relay signals received at the receptors on the cell surface.

33

What are some potential responses to the signal transduction pathways?

May lead to activation of genetic material (DNA)
-This can lead to the production of proteins

34

Explain the signal transduction of steroids

-Lipid soluble hormone passes through the cell membrane and binds to a receptor in the cytosol
-Then forms a hormone-receptor complex
-Then the complex enters the nucleus
-Then the complex will act on genes

35

Discuss hormone longevity

Hormones do not last forever
Once they have delivered their message they are degraded by enzymes
Excreted the body via kidneys or faeces

36

Explain the steps o the negative feedback model if there is an increase in temperature

Stimulus-Increase in temperature
Receptor-Thermoreceptor
Control Center- CNS
Effector- Sweat glands and blood vessels
Response- Sweating and blood vessels dilate
Feedback- Decrease in body temperature

37

Explain extracellular fluid

Fluid on the outside of the cell
e.g tissue fluid and plasma

38

Explain intracellular fluid

Located on the inside of cells
e.g cytosol

39

Define Homeostasis

Processes which are responsible for maintaining a constant internal environment.

40

What are some aspects of internal environment that need to be kept stable?

-Temp
-pH
-ion concentration and nutrient levels

41

What is the external environment for unicellular organisms?

Water or air

42

What are some ways that unicellular organisms maintain their own internal environment

-Regulate the composition of the cytosol by the cell membrane
-Use flagella to move away from undesired stimuli

43

What are the two main systems involved in coordiniation and regulation of internal environments of multi cellular organisms

Nervous System
Hormonal

44

Steps in stimulus response model

1. Stimulus
2. Receptor
3. Control Centre
4. Effector
5. Response

45

Explain the two steps in negative feedback

-Stimulus is dectected and a response is produced
-The response will either oppose the stimulus or bring back the original stimulus to normal levels

46

What organisms are chemical messengers found in?

Plants and Animals

47

What are the main groups of hormones?

Steroids
Protein/peptide
Amino acid derivatives

48

Explain why hormones act on specific cells?

They only act on cells that have a specific cell receptor site that is only found within the target cell. IF the cell does not have that specific receptor site then it will not bind to it. `

49

Where are protein based hormones receptors located?

Outside of the cell

50

Where are lipid based hormones receptors located?

Within the cytoplasmic

51

Briefly explain cell junctions

Allow molecules to readily pass through adjacent cells wwithout crossing cell membranes.
-Occurs in both plant and animal cells

52

What are the two broad groups that hormones are placed in?

-Water soluble
-Lipid Soluble

53

What are the three steps in cell signalling?

1. Signal reception
2.Signal Transduction
3. Cell's Response

54

What does each step in signal transduction lead to the molecule becoming?

Amplified

55

Explain the process of signal transduction when a g protein-linked receptor is involved

-A protein or peptide hormone will activate a membrane receptor
-May activate G protein
-G protein causes a cascade and therefore signal transduction
- Leading to cells response

56

Explain signal transduction in regards to steroid hormone receptors

1. Lipid soluble hormone passes through the cell membrane
2. Binds to a receptor protein found inside of the cells
3. Hormone-receptor complex enters the nucleus
4. Binds to s specific regulator site for the targeted gene
5. Simtulating the gene to produce mRNA
6. Then read by ribosomes to produce a specific protein


(essentally activates gene expression)

57

Explain the role of auxins in plant cells

Cause growth and elongation of plant cells

58

What do auxins cause

Positive phototropism (plant grows in the direction of the light)

59

Where are auxins most commonly found in the plant?

In the dark side as they move away from the light
hence the elongate more due to the unevenness in the shoot.

60

Explain cytokinins

Cause growth and divison of plant cells

61

explain ethlyene

Promotes ripening of fruit

62

abscisic acid

prohibits plant growth and prevents excess loss of water

63

gibberellins

promotes growth and development of plant cells

64

What are pheromones


a chemical substance produced and released into the environment by an animal, especially a mammal or an insect, affecting the behaviour or physiology of others of its species.