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Physiology And Disease > Homeostasis - Topic 1 > Flashcards

Homeostasis - Topic 1 Flashcards

1
Q

What is Homeostasis?

A

The ability to maintain internal biological stability while adjusting to external changes

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2
Q

What does homeostasis allow?

A

Allows the body to control a number of variables within an optimal range (set point) for survival

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3
Q

List examples of what the body needs to control in order to survive.

A

Temperature
pH
Blood-glucose
Salt/water balance
Blood pressure

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4
Q

What is a regulated variable and give an example

A

Variable that is directly sensed by the body and controlled.
Eg: arterial pressure (blood pressure)
Blood pH
Blood pO2/pCO2 (partial pressure)

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5
Q

What is a nonregulated variable and give an example

A

Variable indirectly sensed by the body but still controlled.
Eg: heart rate (changed to regular blood p)
Breathing rate (changed to regulated blood pCO2/pO2)

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6
Q

What is a nonregulated variable and give an example

A

Variable indirectly sensed by the body but still controlled.
Eg: heart rate (changed to regular blood p)
Breathing rate (changed to regulated blood pCO2/pO2)

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7
Q

What are the 3 things homeostasis needs to do to keep the body close to a set point (optimum)?

A

Detect change = receptor/sensor
Process these signals = control centre
Change body state via output = effector

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8
Q

What are the 3 things homeostasis needs to do to keep the body close to a set point (optimum)?

A

Detect change = receptor/sensor
Process these signals = control centre
Change body state via output = effector

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9
Q

What is negative feedback?

A

The primary mechanism of homeostasis. Sensors, control centre and effective work together to reverse effects of change in condition to bring body back to a set point.

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10
Q

What does negative feedback allow?

A

Fine-tuning of conditions through small conditions. Then it “turns itself off” when conditions are back to the set point.

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11
Q

Describe a basic negative feedback loop

A
  1. Deviation from a set point caused by stimulus
  2. Change detected by receptor
  3. Info (as electrical impulse or hormones) is sent to a CONTROL CENTRE
  4. Change counteracted by an EFFECTOR
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12
Q

What is the most common control centre in the negative feedback mechanism?

A

The brain. (CNS = brain and spinal cord)

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13
Q

Give an example of effectors

A

Glands (eg sweat glands)
Muscles (eg erector pili muscles that raise body hair/muscles in iris)

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14
Q

What are the 2 different categories for the effects of negative feedback?

A

Behavioural and physiological changes

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15
Q

Give an example of a behavioural effect when body temp falls

A

Add clothes
Have a hot drink

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16
Q

Give an example of a physiological effect when body temp falls

A

Decrease blood flow to skin
Start to shiver

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17
Q

Give an example of a behavioural change when body temp rises

A

Remove clothes
Have a cold drink

18
Q

Give an example of a physiological change when body temp rises

A

Increase blood flow to skin
Start to sweat

19
Q

What is positive feedback?

A

An uncommon mechanism generally not involved in homeostasis that works to amplify the response to changes in condition.

20
Q

Give an example of positive feedback

A

Uterus stretched during labour - needed so cervix stretches more to birth baby

21
Q

What can prevent homeostasis, leading to extreme conditions like hyper/hypothermia, heatstroke or even death?

A

Neurological diseases or damage to nerves. This interrupts communication, so signals are disrupted. Effector cannot carry out response to counteract the original stimuli if it doesn’t receive an impulse.

22
Q

How is homeostasis implemented?

A

Communication via signalling systems - nervous and endocrine.

23
Q

What is the nervous system?

A

A network of connected nerve cells (neurons) that allow communication of information and control throughout the body. This allows targeted signalling between body and brain.

24
Q

Finish the sentence (hint:DPP)
“nervous systems allow information from the environment to be…”

A

Detected
Processed
Produce behavioural output.

25
Q

The nervous system controls both…

A

Conscious and unconscious control of bodily functions

26
Q

What is the CNS?

A

Central nervous system - brain and spinal cord

27
Q

What is the PNS?

A

Peripheral nervous system - peripheral nerves outside brain and spinal cord

28
Q

What does the PNS do?

A
  1. Detect external (eg touch) and internal (eg organ function) stimuli and processes information from and to the brain
  2. Controls conscious movement and unconscious autonomic function (organ function- heart beat)
29
Q

What does the CNS do?

A

Processes internal and external information relayed to it and can communicate with the PNS to act on effectors.

30
Q

What is an input?

A

Sensory info carried TO the CNS for processing (afferent = towards)

31
Q

What us an output?

A

Information carried AWAY from CNS to act on effectors (efferent = away)

32
Q

When an impulse is going in the afferent direction, what are the two main types of control?

A

Autonomic - involuntary control of tussues/organ systems
Somatic - voluntary control of skeletal muscle

33
Q

What is the autonomic response divided into?

A

Sympathetic - flight/fright/freeze
Parasympathetic - rest/digest

34
Q

Describe the negative feedback mechanism caused by temperature change

A
  1. Receptors in the skin detect a change in temp from a set point. Signal to brain.
  2. Signal processed by brain (eg hypothalamus)
  3. Brain activates effectors to counteract change and bring temp back to the set point (eg sweat glands) and the mechanism turns off.
35
Q

What is the nervous system?

A

An irgan system which neurons are the primary functional unit. It allows internal and external stimuli to be detected, processed and have a response coordinated. It can control convous and unconscious processes.

36
Q

What is the autonomic nervous system?

A

A branch of the peripheral efferent nervous system that regulates organ function and has 2 subdivisions - sympathetic and parasympathetic

37
Q

What is the somatic nervous system?

A

Branch of peripheral nervous system that controls the body’s skeletal muscles for voluntary movement. (BUT Motor neurons from spine are often considered part of the CNS)

38
Q

What is a sensory division?

A

Branch of the PNS involved in sensory detection of Internal and external stimuli m, and relay of this to the CNS.
EG. vision, hearing, somatosensation (touch) and visceral senses (internal organ senses)

39
Q

What is extracellular (aka intercellular) fluid?

A

Cells environment
I.e, interstitial fluid and plasma

40
Q

What is intracellular fluid?

A

Solution within the cells (intracellular environment?

41
Q

Give examples of factors that must be maintained by homeostatic control

A

Concentration of solution and nutrients, pH, temperature, volume/pressure of body fluids and O2/CO2 concentration.

Physiology And Disease (10 decks)

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