Homeostasis

Question 1

4 things homeostasis imbalance can result from:

Answer 1

Aging
Genetic mutations
Pathogens
Environment

Question 2

Definition of homeostasis

Answer 2

The ability of an organism to maintain its internal environment despite change to its internal and external environment

Question 3

5 sensory receptors in external environment:

Answer 3

Mechanoreceptors
Thermoreceptors
Electromagnetic receptors 
Nociceptors
Chemoreceptors

Question 4

Internal environment

Answer 4

Helps efficient cell/organ/system function

Question 5

What’s included in the internal environment?

Answer 5

EC fluid, IF, intravascular fluid

Question 6

T/F internal environment is controlled within a narrow range:

Answer 6

T

Question 7

What does the internal environment detect?

Answer 7

Level of chemicals in blood/tissues

Question 8

Examples of chemicals in blood/tissues:

Answer 8

Glucose, O2, CO2, H2O, ions

Question 9

What is the stimulus to response pathway?

Answer 9

Stimulus –> receptor –> control center –> effector –> response

Question 10

Can the stimulus to receptor response be nervous system or endocrine?

Answer 10

Both!

Question 11

Characteristics of nervous system response:

Answer 11

APs, transported by neurons, fast, short, voluntary/involuntary, local

Question 12

Characteristics of endocrine response:

Answer 12

Hormones, transport by blood, slow, short or long, always involuntary, distant, many cells effected

Question 13

Definition of neurohormones:

Answer 13

Chemicals released by neurons into blood for action at a distant target organ / tissue

Question 14

Example of neurohormone pathway:

Answer 14

1 hypothalamic neurons make oxytocin/ADH
2 oxy/ADH transported down axons of hypothalamus (hypophyseal tract) to PP
3 stored in PP
4 hypothalamic neurons fire, AP arrives at terminals
5 oxy/ADH released into blood

Question 15

Autocrine:

Answer 15

Acts on same cell

Question 16

Paracrine

Answer 16

Acts on adjacent cell

Question 17

Characteristics of lipid-soluble hormones:

Answer 17

Lipophilic
Ex: steroids, calcitriol
DO transport proteins 
Long plasma half life
Intracellular receptors 
Mediator: receptor-hormone complex

Question 18

Characteristics of water soluble hormones:

Answer 18

Hydrophilic
Ex: polypeptides, glycoproteins, catecholemines
DONT transport proteins
Short plasma 1/2 life
Uses plasma membrane receptors
Mediators: cAMP, cGMP, Ca, kinase cascades

Question 19

Hormone response model:

Answer 19

Receptor –> integrator (brain) –> effector (muscle/gland) –> response —> feedback

Question 20

Negative feedback definition:

Answer 20

Body senses change = stimulation = feeds back to reverse the change. MOST COMMON kind of feedback

Question 21

Ex of negative feedback

Answer 21

Body temp changing, negative feedback brings it back to homeostasis

Question 22

Mechanism of negative feedback:

Answer 22

Stimulus that homeostasis is not in balance –> integration of signal at hypothalamus (TRH) –> AP releases TSH (effector) –> thyroid gland releases hormones into blood –> NEGATIVE FEEDBACK and homeostasis restored

Question 23

Definition of positive feedback:

Answer 23

Self-amplifying physiological change that leads to even greater change and builds off of itself. Can be detrimental unless corrected by cessation. LEAST COMMON kind of feedback

Question 24

Ex of positive feedback

Answer 24

Parturition

Question 25

Mechanism of parturition as an example of positive feedback:

Answer 25

Stretch receptors in uterus –> signal to brain to release oxytocin into blood –> POSITIVE feedback to uterus to contract more forcefully –>cycle keeps going until cessation

Question 26

Moderate homeostatic imbalance:

Answer 26

Disorder/abnormality of structure/function disease with specific signs / symptoms, signs and symptoms are subjective (ex fever)

Question 27

Severe homeostatic imbalance:

Answer 27

Results in death

Question 28

How is heart failure an example of both negative and positive feedback?

Answer 28

System tries to correct imbalance = negative feedback, but then becomes overwhelmed and destructive positive feedback takes over