L.1 - homeostasis Flashcards
(43 cards)
1
Q
What is the Greek meaning of homeostasis?
A
- same & steady
2
Q
What does homeostasis refer to?
A
- Any process that living things use to actively or dynamically maintain.
- Fairly stable internal body conditions (so called ‘steady state’) necessary for survival even though the external environment changes continuously.
3
Q
What does steady state mean?
A
Fairly stable internal body conditions necessary for survival
4
Q
What are homeostatic control systems?
A
- The compensation mechanisms that help maintain a stable internal environment.
5
Q
What are proteins protected by?
A
- by homeostatic mechanisms.
- it protects the integrity of the protein products of gene translation.
6
Q
What does the tertiary structure of a protein result from?
A
- Results from the folding of amino acid chains (hydrogen bonds and Vanderwall’s forces)
- These forces are sensitive to change in the environment surrounding the proteins such as acidity, temperature, osmotic potential.
7
Q
What does it mean when a protein is denatured?
A
- It means the proteins shape alters to a point that they are nonfunctional or irreversibly damaged as they cannot tolerate the degree of change in internal environment.
8
Q
Accumulation of damaged proteins is responsible of what 2 diseases?
A
- Alzheimer’s disease
- Creutzfeldt-Jakob disease
9
Q
What disrupts homeostasis?
A
- the changes to the internal and external environments.
10
Q
What are examples of changes to the external and internal environment that can disrupt homeostasis?
A
- external environment: intense heat or lack of oxygen
- internal environment: drip in blood glucose due to lack of food
11
Q
What are the forms of disruptions that can happen to the external and internal environment?
A
- mild and temporary (balance is quickly restored)
- intense and prolonged (loosening or severe infections)
12
Q
What does homeostatic control require?
A
- Communication within the body and this is accomplished mainly by the nervous and endocrine systems which use electrical impulses and hormones to carry information.
13
Q
Are homeostatic mechanisms reflex or not- reflexive?
A
- they are reflexes that occur subconsciously
14
Q
What is a variable?
A
- And the factor or condition being regulated such as temperature or blood pressure.
15
Q
What are some of the components of a homeostatic control mechanism?
A
- receptor/sensor
- afferent pathway
- set point or reference value
- integrator/control center
- efferent pathway
- effector
16
Q
What is a receptor & what does it do? Give an example.
A
- a body structure that monitors changes in a variable
- it sends input to the control centre through afferent pathways.
- An example would be the nerve ending of the skin in response to temp change.
17
Q
What is the control centre and what is it’s function?
A
- control center is the brain (hypothalamus)
- it determines the set point/reference value for a variable such as normal body temperature range.
- it evaluates input received from the receptors and generates output command
- gives off nerve impulses and hormones
18
Q
What is the effector & what does it do?
A
- it receives output from the control centre via efferent pathways.
- it produces a response or effect that changes the value of the variable.
- example: shivering to generate heat and thereby increase body temperature
19
Q
What happens to the homeostatic control process when the results of the response feedback to the control centre?
A
The homeostatic control process either:
• shuts off (negative feedback)
• or enhances so that the whole process continues at an even greater rate (positive feedback)
20
Q
What are 6 examples of variables controlled by homeostasis?
A
• body core temperature
• arterial blood pressure
• arterial O2 and CO2 concentration
• osmoregulation-water balance
• blood glucose concentration
• extracellular sodium and potassium concentration
21
Q
Is arterial pressure homeostatically regulated?
A
- no. It is regulated by the changing heart rate, stroke bike, and peripheral resistance which are called ‘control variables’
22
Q
Are controlled variables homeostatically regulated?
A
- no. For example: heart rate is a controlled variable. It is not controlled around a set point but instead it’s main role is to contribute to blood pressure regulation.
23
Q
What type of feedback are must homeostatic control mechanism?
A
- ## most are negative feedback systems
24
Q
Explain what negative feed back system is?
A
- it reverses a change in the variable by either shutting off the original effect of the stimulus or reducing its intensity.
- the mechanisms cause the variable to change in the opposite direction to that of the initial change
- variable returns back to set point.
Example would be regulation of blood pressure and body temperature
25
What are examples of negative feedback systems?
- regulation of blood pressure
- regulation of body temperature
26
Explain the negative feedback in regards to regulation of blood pressure.
- external or internal stimulus increase BP
- Baroreceptors (pressure sensitive receptors) detect higher BP
- it sends nerve impulses to brain for interpretation
- response sent via nerve impulse sent to heart and blood vessels
- BP drops and homeostatic is restored
- Drop in BP negates the original stimulus
27
Explain the negative feedback in regards to regulation of body temperature.
- Stressor: body temp increases
- Sensors: specialized neurone detect change from set point
- integrator: temp regulating center in hypothalamus is body’s thermostat
- sympathetic nervous signal effectors. Motor neurone send signals to muscles. Prefrontal cortex sends signals
- effectors: either individual takes action (find shade), muscle activity decreases, blood vessels in skin dilate, sweating increases/panting
- response: body temp decreases
- FINALLY HOMEOSTASIS IS RESTORED BITCH
28
Explain the function of positive feedback.
- A positive feedback mechanism is the exact opposite of a negative feedback mechanism.
- The response enhances the original stimulus.
- The response is positive because it is in the same direction as the initial change.
- The value of the variable deviates further from his original said value.
- An example would be childbirth and blood clotting.
29
Explain the positive feedback system in regards to normal child birth.
- Uterine contractions cause cervix to open.
- Stretch sensitive receptors in service and impulses to the brain.
- Oxytocin hormone is released into the blood.
- Contractions enhanced and baby pushes further down the uterus.
- Cycle continues to the birth of the baby (no stretching.)
30
Explain the positive feedback system in regards to blood clotting.
- Break or tear in blood vessel wall. Feedback cycle is initiated.
- Clotting occurs as platelets adhere to cite and release chemicals.
- Released chemicals attract more platelets.
- Clotting proceeds until break is sealed by newly formed clots.
31
What is a set point in homeostasis?
- Homeostatic control systems cannot maintain a variable at complete concert constancy.
- Any regulated variable will have a range of normal value depending on multiple factors such as age, time of day, eternal environmental conditions, etc.
- for example the average normal body temperature is generally accepted as 37°C. However I can have a wide range of 36.1°C to 37.2°C.
- Set points can be physiologically resets on your value.
- For example during a fever the body temperature is raised to over 37°C in response to infection. This is an adaption for fighting infection because of the proliferation of some pathogens temperature regulation however still occurs around this set point.
32
What is adaption?
- A characteristic that favours survival in specific environments. Homeostatic control systems are inherited biological adaptions.
33
Is adaption fixed or can it prolong exposure to stress?
Ability to respond to environmental stress is not fixed. It can be enhanced by prolonged exposure to that stress.
34
What is acclimatization?
- increase and more rapid sweating with repeated exposure to heat. This type of adaption which is an improvement if an already existing homeostatic system called acclimatization.
35
Can acclimatization be reversible? If yes, how so?
- yes it is usually reversible with the discontinuation of the environmental stress.
36
What is circadian rhythm? Give examples.
- a common rhythm that occurs once every 24 hours.
- For example: waking and sleeping, body temperature, growth hormone released.
37
What controls the internal biological rhythms?
- hypothalamus
38
What can affect cycles and mood?
- light exposure
39
How do biological ruthenium add an anticipatory (or feed forward) component to homeostatic control systems? Give an example.
- by activating them at times when change likely to occur but before it actually does.
- example: Body temperature increases prior to working in a person on a typical sleep wake cycle. This allows metabolic machinery of the body to operate most efficiently upon waking as metabolism is partly temperature dependent. During sleep, metabolism slower than during active hours, and therefore body temperature decreases at this time.
40
What 5 factors affect the performance of homeostatic mechanisms (which causes imbalance)?
- aging
- nutritional status
- disease causing organisms
- excessive stress
- extreme environmental conditions beyond control
41
What are the 2 types of imbalances that may office if normal homeostasis of body processes are disrupted?
- moderate imbalance and severe imbalance.
42
Explain moderate and severe imbalance respectively.
Moderate imbalance:
- Disorder or abnormality of structure and function.
- Disease specific for an illness with recognizable signs and symptoms.
• Signs are objective changes such as a fever swelling.
• Symptoms are subjective changes such as a headache.
- Treatment to restoration of homeostasis.
Severe imbalance:
- Treatment fails to restore homeostasis. - Illness and death results. 
43
Explain the homeostatic imbalance in type 1 diabetes.
- beta cells of the pancreatic islets are destroyed.
- insulin is no longer produced.
- blood glucose continues to rise.
- the condition is fatal if not treated.
