Endocrine System

Question 1

What is the endocrine system

Answer 1

The collection of glands and secretory tissues whose function is to regulate multiple organs in the body

Question 2

What are the 2 functions of the endocrine system

Answer 2

1. Respond to fluctuations within the internal environment to maintain homeostasis
2. Meet growth and reproductive needs of organism

Question 3

Why do animals have endocrine system instead of paracrine

Answer 3

Acts via hormones and blood stream because the target cells are too distant to be reached by diffusion

Question 4

Autocrine signalling

Answer 4

cell releases the signal to which it itself responds to

Question 5

How does the endocrine system work

Answer 5

Migrate substance into circulatory system which allow substances to travel throughout the body, and be released from the circulatory system to cells throughout the body

Question 6

How do paracrine signals work

Answer 6

Diffuses into the interstitial fluid and elicits its response in the neighboring cells (gradient of signal, the further the fell is away from the source the less it will see)

Question 7

Where are hormones produced

Answer 7

endocrine cells

Question 8

What are endocrine cells

Answer 8

Ductless organs excrete outside the cell, into interstitial fluid where it then diffuses into the circulatory system

Question 9

Why do endocrine glands have lots of capillaries

Answer 9

Dense network of capillaries in endocrine glands to quickly take up hormones and spread them throughout the body

Question 10

How many endocrine glands do we have and what are they

Answer 10

9 overall, 8 per sex

    - Pineal
- Hypothalamus
- Pituitary gland (master regulator)
- Thyroid Gland
- Parathyroid Gland
- Adrenal Glands
- Pancreas
- Ovaries 
    -Testes

Question 11

What are hormones

Answer 11

Chemical signals that are secreted into the circulatory system and communicate regulatory messages throughout the body.

(Long-distance regulators in the body)

Question 12

What do protozoans use as communication signals

Answer 12

Use secreted chemicals called pheromones (or gamones) for mating purposes

Question 13

Why do protozoans need pheromones

Answer 13

communicate to undergo sexual reproduction

Question 14

Protozoans

Answer 14

unicellular eukaryotes

Question 15

metazoans

Answer 15

multicellular animals

Question 16

What happened with the development of multicellularity

Answer 16

metazoans established short distance paracrine signalling

Question 17

Limitations of paracrine signalling and the effect of this

Answer 17

limited to a distance of about 10 cells (limited to simple animals)

Question 18

What version of endocrine system do phyla with lower physiological and anatomical complexity have

Answer 18

Neural systems but not an endocrine or circulatory system because they have lower physiological/anatomical complexity

Question 19

Where does paracrine signalling occur in the neural system

Answer 19

At the end of axons, in the synapse

Question 20

Where are chemical signals released in the neuron

Answer 20

By the synapse, at the end of the axon

Question 21

Why not ONLY use the nervous system to communicate over long distances

Answer 21

Does not suffice due to dilution effect

Question 22

2 advantages of endocrine system in addition to a neural system

Answer 22

A) blood vessels are designed to reach every cell in the body (because every cell in the body needs oxygen, nutrients, excretion)

B) Hormones are more suited for long-term effects (minutes to years) - whereas nerves work on more immediate responses

Question 23

Why does the endocrine system require the circulatory system

Answer 23

Allow long-distance dispersal of chemical signals to alll the cells in the body

Question 24

How did endocrine glands form

Answer 24

Hormone-producing cells accumulated together into glands

Question 25

Function of endocrine glands

Answer 25

Allowed secretion of large amounts of hormones into capillary beds for dispersion around the body.

Question 26

First endocrine glands

Answer 26

Neurohemal organ

Question 27

What organisms has neurohemal organs

Answer 27

Mollucs and earthworms

Question 28

What is the neurohemal organ

Answer 28

Neurons bundled together

Question 29

Summary of the evolution of endocrine glands/system

Answer 29

Summary
1) Started with single cells organisms that used only pheromones
2) As we became multicellular, we used paracrine signalling (cell to surrounding cells and neural synapses)
3) As multicellular organisms became bigger, and circulatory systems developed, endocrine signalling was born
4) Accumulation of hormone-secreting cells into glands (“endocrine glands”) containing capillary beds

Question 30

3 classes of hormones

Answer 30

Polypeptide hormones, Steroids, Amines

Question 31

Polypetide hormones

Answer 31

• Chains of Amino acids
  
  • Range from 3 amino acids to about 200 amino acids (size of a protein)

Question 32

Why are polypeptide hormones ideal

Answer 32

Hormones usually work with a receptor - use the key and lock mechanism - Polypeptide has the greatest range of shapes

Question 33

Steroids

Answer 33

Based on basic backbone of cholesterol

Question 34

Amines

Answer 34

Built of single amino acids or single amino acids hooked together to another

Question 35

What amines are water soluble

Answer 35

Polypeptides and epinephrine

Question 36

What hormones are fat soluble

Answer 36

All cholesterol and other amines are fat-soluble

Question 37

How do water soluble hormones work

Answer 37

• Water soluble hormones cannot freely cross the cell membrane.
• To be released, they have to be bundled in vesicles and released during an active process. - Once excreted, they can freely dissolve into and out of capillaries. However, they need a receptor to get into target cells.
• Once they bind to the receptor, it elicits a downstream effect that changes a cell to respond to the release of that hormone

Question 38

How do fat-soluble hormones work

Answer 38

• Fat-soluble hormones cannot be retained in the cell that produces it.
• They immediately cross the lipid membrane however they are not very soluble in interstitial fluid and blood vessels.
• Must be carried around by a carrier protein - they can diffuse into all cells (even those that aren’t target cells) but only certain cells will have a receptor for that certain steroid.
• The cells with the certain receptor bind the steroid and eliciting a response.

Question 39

Epinephrine hormone different effects on different cells

Answer 39

In liver cells - the release of glucose (increase glucose levels)
In smooth muscle cells in blood vessels that supply blood to muscles - relaxation (increased flow)
In smooth muscle cells in blood vessels that supply blood to intestines - contracts (decrease flow)

Question 40

Connection between neural and endocrine system

Answer 40

Hypothalamus

Question 41

Location of hypothalamus

Answer 41

situated at the base of the brain, connected to the anterior pituitary

Question 42

How does hypothalamus mechanism work

Answer 42

Hormones produced inside hypothalamus, travel down the axons, and are released at the synapses into the capillary bed. Then they travel to pituitary gland which may release hormones - which then travel further around the whole body

Question 43

The main role of endocrine system

Answer 43

Maintain internal homeostasis

Question 44

Negative feedback loop

Answer 44

Inhibits a response by reducing the initial stimulus, preventing excessive pathway activity

Question 45

How does negative feedback loop work in duodenum

Answer 45

• When chyme is passed into duodenum, it comes with a lot of acidity.
• Responder cells (S cells) measure PH. If it gets very acidic they cause the secretion of a hormone which travels around the body, eventually hitting the target cells in the pancreas.
• The pancreas responds by producing bicarbonate (pancrease is an exocrine gland) which dumps bicarbonate into duodenum to remove low pH, remove stimulus, so S cells no longer produce secretin.