Week 7

Question 1

What are gap junctions?

Answer 1

Form direct cytoplasmic connections between adjacent cells

Question 2

What are contact dependant signals?

Answer 2

Require interaction between membrane molecules on two different cells.

Question 3

What are autocrine signals?

Answer 3

Act on the same cell that secreted them.

Question 4

What are paracrine signals?

Answer 4

Are secreted by one cells and diffuse to adjacent cells

Question 5

What is long distance communication?

Answer 5

Electrical signals carried by nerve cells and chemical signals transported in the blood.

Question 6

What is the general pattern of a signalling pathway?

Answer 6

1. Signal binds to a membrane receptor protein
2. This activates membrane receptor protein
3. Activation of membrane protein receptor subsequently modifies the existing proteins
   4.alteration of protein creates a response

Question 7

What is the difference between chemical and electrical signals?

Question 8

What are the differences between endocrine and neural control?

Answer 8

Neural: more specific, electrical signal passes form nerve to nerve, very rapid, short response, stimulus intensity correlated with frequency of signalling.
Endocrine: chemical signal secreted in blood, much slower, long response, stimulus intensity correlated with amount of hormone secreted

Question 9

Describe the neural control pathway for reflexes.

Answer 9

1.stimulus (internal/external change)
2.receptor
3. Input signal (Sensory neuron)
4. Nervous system integrating centre
5.efferent neuron
6.target
7.response

Question 10

Describe the neuroendocrine control pathway for reflexes.

Answer 10

1.internal/external change
2. Sensory neuron
3.hypothalamus/ posterior pituitary
4. Neurosecretary cell
5.blood vessel
6. Target effectors
7.response

Question 11

Describe the endocrine control pathway for reflexes.

Answer 11

1.internal/external change
2. Endocrine system sensory-integrating centre
3.output signal: hormone
4.target
5.response

Question 12

What is an exocrine gland?

Answer 12

An exocrine gland secretes is contents through ducts onto the epithelial surface eg/ sebaceous glands

Question 13

What is an endocrine gland?

Answer 13

Secrete hormone which are directly released into the blood stream

Question 14

What are the 3 classes of hormone groups?

Answer 14

Lipid-Derived Hormones, amino-acid derivatives, and Peptide or Protein Hormones.

Question 15

What is the structure of amino acid derivatives?

Answer 15

Small molecules structurally related to individual amino acids.
Separated into two classes: derivatives of tyrosine (catecholamine, thyroid hormones), derivative of tryptophan.

Question 16

What is the structure of peptide/protein hormones?

Answer 16

Chains of amino acids, are either glycoproteins or short polypeptides and small proteins.
Two classes: glycoproteins, and short polypeptides and small proteins

Question 17

What is the structure of Lipid-Derived hormones?

Answer 17

Made up of carbon rings and side chains built from fatty acids or cholesterol
Two classes: eciosanoids, steroids hormones.

Question 18

What is the difference between water vs lipid soluble hormones?

Answer 18

-lipid soluble: circulate bound to transport proteins
-water soluble: circulate freely in plasma

Question 19

What factors affect mechanisms of hormone action?

Answer 19

• hormone, target cell

Question 20

What are some example of responses to hormone action?

Answer 20

Synthesis of new molecules, changing cell membrane permeability, stimulating transport of substance into or out of cell, altering rate of metabolic actions, causing contraction of smooth of cardiac muscle.

Question 21

What are the mechanisms of lipid soluble hormone action?

Answer 21

1. Lipid soluble hormone diffuses into cell (after from detaching from transport protein in blood)
2. Activated receptor-hormone complex alters gene expression
3. Newly formed mRNA directs synthesis of specific proteins on ribosomes
   4.protein alters cells activity

Question 22

What are the mechanism of water-soluable hormone action?

Answer 22

1. Binding of hormone to receptor protein which activates G protein which in turn activates adenylate cyclase
   2.activated adenylate cyclase converts ATP to cAMP
   3.cAMP serves as second messenger to activate protein kinases
2. Activated protein kinases phosphoryate cellular proteins
3. Millions of phosphorylated proteins cause reactions that produce physiological responses
4. Phosphodiesterase inactivates cAMP

Question 23

What is the relationship between the hypothalamus and pituitary gland?

Answer 23

The posterior pituitary gland stores and secretes hormones creates by the hypothalamus.
Anterior pituitary gland synthesises its own hormones however the secretion of these hormones is regulated by the hypothalamus

Question 24

What are the two hormones secreted by the posterior pituitary gland?

Answer 24

Oxytocin: acts on uterus and mammary glands
Antiduretic Hormone (ADH): acts on kidneys; retainss body water, and increases blood pressure.

Question 25

What is the difference between intracellular and cell membrane receptors?

Answer 25

Intracellular: diffuse through membrane; slower responses related to changes in gene activity Cell Membrane: bind to cell membrane receptor, triggers rapid cellular responses.

Question 26

What are the major endocrine organs?

Answer 26

Pineal gland, pituitary gland, thyroid gland, parathyroid glands, thymus, adrenal gland, pancreatic islet cells, ovaries and testes.

Question 27

What are some examples of hormone action?

Answer 27

Synthesis of new molecules, changing perambility of cell membrane, stimulating transport of substance into or out of the cell, altering rate of metabolic action and causing contraction of smooth or cardiac muscle.

Question 28

What can effect a target cells response to a hormone?

Answer 28

Hormones concentration in blood, number of hormone receptors on cell, influences exerted by other hormones

Question 29

What is a synergistic effect?

Answer 29

Where some hormones work more effectively when a second hormone is present to assist them

Question 30

What is the antagonistic effect?

Answer 30

Some hormones apples the actions of others

Question 31

What is the process of secretion and actions of antidiuretic hormone?

Answer 31

1. High blood osmotic pressure stimulates hypothalamic osmorecptors 2. Osmoreceptors activate neurosecretory cells that synthesise and release ADH 3. Nerve impulses release ADH from axon terminals in the posterior pituitary into blood stream 4. Causes: kidneys to retain more water (decreasing urine output), sweat gland decrease water loss via perspiration and arterioles constrict (increase blood pressure)