Chapter 35 Control by Endocrine System and Nervous System

Question 1

What is the role of the endocrine system

Answer 1

Secrete hormones into the bood

Question 2

What are the differences between nervous control and Endocrine control

Answer 2

Nervous

• Fast (travel fast but end quickly)
• Addressed - nerve impulses to specific target cells

Endocrine

• Slow but prolonged (often alter gene transcription)
• Broadcast - all cells re potentially exposed to hormone.

Question 3

How do the endocrine and nervous systems work together?

Answer 3

Brain controls secretion of many hormones

Sex hormones affect brain development during puberty

Question 4

What are the different types of chemical signals

Answer 4

Paracrines - affect neighbouring cells
Autocrines - affect same cell as secreting cell
Hormones - carried through blood
Neurotransmitters - move across synaptic cleft
Pheromones - released into environment, affect other individuals

Question 5

What are exocrine glands

Answer 5

Secrete substances into a duct or body cavity

Question 6

What are endocrine glands

Answer 6

Secrete directly into blood

Question 7

What are hormones

Answer 7

chemical substances that are secreted into blood by endocrine cells and regulate function of other cells

• act in low concentrations
• effects on target cells are initiated by noncovalent bonding of hormone to receptor protein

Question 8

What are neurosecretory cells?

Answer 8

exciable cells that propagate action potentials - resemble neurons

• direct interface between nervous and endocrine systems
• Cell body in CNS, axon terminas release hormones

Question 9

What are the 3 groups of hormones

Answer 9

Peptide and protein hormones
Steroid hormones
Amine hormones

Question 10

What are the properties of peptide and protein hormones?

Answer 10

water soluble and easily transported in blood; packaged in vesicles and released to blood by exocytosis
Cannot cross membrane so receptors are external

Question 11

What are the properties of Steroid hormones

Answer 11

Synthesized from cholesterol
Lipid soluble
Bound to carrier proteins in blood
Receptors inside target cells

Question 12

What are the properties of Amine hormones

Answer 12

modified amino acids

may be lipid or water soluble so receptors may be inside or outside target cell

Question 13

Describe the bonding of hormones to external receptor proteins on target cell

Answer 13

Hormone binds to part of receptor that projects outside cell membrane
Many receptors initiate second messenger signalling cascade inside cell

Question 14

Describe the bonding of hormones to internal receptor proteins in target cell

Answer 14

Lipid soluble hormones cross cell membrane and receptors are in cytoplasm
Hormone-receptor complex mvoes into nucleus and affects gene expression

Question 15

How does negative or positive feedback affect hormone function

Answer 15

Can affect number of receptor protens on cell

- Chronic high levels of hormones -> decrease in recceptors -> cells less sensitive

Question 16

How can hormones ellicit different responses from different target cells

Answer 16

Target cells have different receptor systems

Question 17

What are the actions of adrenaline, why are there so many

Answer 17

5 types of G-protein linked receptors that are either a-adrenergic of b-adrenergic

Responses:

• increase HR and contraction
• Skin blood vessel vasoconstriction
• Skeletal muscle blood vessel vasodilation
• Breakdown of glycogen in liver
• Decrease in bloodflow and secretion of digestive enzymes in gut

Question 18

Why does timing of hormone release vary

Answer 18

Depends on if hormones are synthesized prior to use and stored for quick release (peptide hormones) or if they are synthesized on demand (steroid hormones)

Question 19

How are hormones removed from the blood

Answer 19

Degraded enzymatically by organs such as liver and kidneys or target cells
OR excreted

Question 20

What kinds of hormones have longer half lives

Answer 20

Ones transported on carrier proteins

Question 21

Describe the anatomy of the Posterior pituitary gland

Answer 21

extension of brain - is a neurohemal organ where neurosecretory cells with cell bodies in hypothalamus secrete hormones in posterior pituitary gland from axons

Question 22

What hormones are secreted from the posterior pituitary gland

Answer 22

Antidiuretic Hormone

Oxytocin

Question 23

What hormones are produced by the anterior pituitary gland

Answer 23

4 Tropins

• Adrenocorticotropin hormone
• Thyrod stimulaing hormone
• Lutenizing hormone
• Follicle-stimulating hormone

AND

• Growth Hormone
• Prolactin
• Melanocyte stimulating hormone

Question 24

What is the anterior pituitary gland

Answer 24

Endocrine gland

Question 25

What controls the secretion of anterior pituitary hormones

Answer 25

hypothalamo-hypophsial portal system - Neurosecretory cells in hypothalamus secrete hormones into capilaries - blood flows to secondary capillary bed in anterior pituitary gland - Neurohormones released are releasing hormones and inhibiting hormones

Question 26

What is an axis

Answer 26

Sequence of endocrine cells acting on each other in sequence

Question 27

Why do neurosecretory cells in hypothalamus often secrete in pulses?

Answer 27

Because continuous secretion can reduce number of receptors and reduce sensitivity Anterior pituitary hormones are also secreted in pulses