Week 1 - Control of the Internal Environment: Homeostasis, Exercise & Adaptation Flashcards

1
Q

Homeostasis

A

maintenance of a constant and “normal” internal environment

“It is the process by which we adapt and adjust to changes in our environment to maintain our functional integrity.”

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2
Q

Hormesis

A

refers to a biological process in which low-to-moderate doses of a potentially harmful stress results in a beneficial adaptive effect

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3
Q

Define steady state exercise and explain how it differs to homeostasis.

A

where physiological variables are unchanged (HR, VO2, Bp) but this doesn’t necessarily mean “normal”

its the balance between demands placed on the body and the body’s response to those demands

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4
Q

What are the two biological control systems of the body?

A

1) Intracellular control systems: protein breakdown/synthesis, energy production, maintenance of stored nutrients (fats and carbs)

2) Organ systems: pulmonary and circulatory systems, replenish oxygen and remove carbon dioxide

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5
Q

What are the 3 general components of a biological control system?

A

Receptor, control center, and effector.

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6
Q

Describe the principles that underlie physiological control of variables.

A

Peripheral receptors/ sensors
- detect changes in the internal conditions of the body (peripheral organs and tissues) and send this afferent information to the brain ‘centres’ which processes and integrates this - (compares present value with desired value)

Control center
- send efferent information to effector organs/tissues either through nerves or hormones (or both) to negate (negative feedback) or to amplify (positive feedback) the change.

Effectors
- bring the internal environment back to normal (negative feedback) or amplify the changes (positive feedback).

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7
Q

What are the two classes of biological control systems?

A

Negative and positive feedback

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8
Q

Define negative feedback and provide an example.

A

where the response reverse the initial disturbance in homeostasis and restores normal values

Example: respiratory systems control of C02 concentration in extracellular fluid (blood)
- Increase in extracellular C02 triggers a receptor/sensor
- Sends afferent information to respiratory control center
- Respiratory muscle activated to increase breathing
- C02 concentration returns to normal

Other examples: blood pressure, heart rate, body temperature

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9
Q

Positive feedback

A

Biological responses amplifies the original stimulus (change)

Example: Childbirth
- Initiation of childbirth stimulates receptors in cervix and sends message to the brain to release oxytocin from pituitary gland
- Oxytocin promotes increased uterine contractions

Other example: clotting of blood after cutting yourself

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10
Q

What is the “Gain” of a biological control system?

A

the degree to which a control system maintains homeostasis - pulmonary and CV systems have large gains (thus more capable of maintaining homeostasis)

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11
Q

Explain the regulation of body temperature in response to exercise.
What happens to effector organs/tissues if core body temperature drops?

A

Body temperature rises as exercise generates heat from working skeletal muscles.
Thermoreceptors detect this change in internal environment of the body and will send afferent information to the hypothalamus (control center).
The hypothalamus sends efferent information to effector organs and tissues which causes the increase in heat loss mechanisms (dilation of blood vessels and activating sweat gland secretion).
This negative feedback response limits the increase in core body temperature and creates a steady state where heat gain from exercise and heat loss is balanced.

If core body temperature drops, effectors constrict blood vessels and sweat glands are inactive.

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12
Q

Adaptation

A

refers to a change in the structure and function of the cell or organ system (often in response to exercise) that results in an improved ability to maintain homeostasis during physiologically stressful conditions (exercise)

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13
Q

Acclimation

A

adaption to environmental stresses (e.g. heat or hypoxic stress), which results in an improved function of existing homeostatic systems

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14
Q

Define Hormesis.

What model can explain exercise-induced hormesis?

A

is the process in which a low-to-moderate dose of potentially harmful stress results in a beneficial adaptive response on the cell or organ system

Exercise-induced hormesis refers to the Inverted U shape model where there is an optimal intensity and duration of exercise stress to induce the greatest beneficial adaptive response - this varies between biological systems (CV, skeletal muscle) and people

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15
Q

5 different types of cell signaling pathways

A

Intracrine signaling
Juxtracrine signaling
Autocrine signaling
Paracrine signaling
Endocrine signaling

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16
Q

Define “Cell signaling” and explain why its important?

A

communication between cells using chemical messengers
this coordinates cellular activities and is important for maintaining homeostasis

17
Q

1) Chemical messengers inside cell triggers response
2) Chemical messengers passed between two connected cells
3) Chemical messengers acts on the same cell
4) Chemical messengers act on nearby cells
5) Chemical messengers (that are hormones) released into the blood and affect cells with specific receptors to the hormone

Paracrine, Endocrine, Intracrine, Juxtracrine, Autocrine

A

1) Intracrine
2) Juxtacrine
3) Autocrine
4) Paracrine
5) Endocrine

18
Q

What part of the body monitors our body temperature?

A

The Hypothalamus (temperature centre located here)

19
Q

Match the systems and the description explaining how they contribute during exercise

Systems: Blood, Renal, CNS, Integumentary, Musculo-skeletal, Respiratory, Cardiovascular, Endocrine, Alimentary

Supports circulation control and regulates metabolism.

Provides 02 and removes C02.

Provides movement under CNS control.

Pumps the blood through the circulation.

Water and nutrient intake.

Involved in heat loss from the body.

Controls Musculo-skeletal system, circulation and body temperature.

Conserves water; contributes to maintenance of body pH.

Carries gases, nutrients and waste products.

A

Endocrine: Supports circulation control and regulates metabolism.

Respiratory: Provides 02 and removes C02.

Musculo-skeletal: Provides movement under CNS control.

CV: Pumps the blood through the circulation.

Alimentary: Water and nutrient intake.

Integumentary: Involved in heat loss from the body.

CNS: Controls Musculo-skeletal system, circulation and body temperature.

Renal: Conserves water; contributes to maintenance of body pH.

Blood: Carries gases, nutrients and waste products.

20
Q

How do feedforward loops differ to regulatory feedback loops?

A

Feedforward loop results in physiological responses in anticipation of a change in a variable whereas regulatory feedback loops act to reduce (negative) or increase (positive) an actual change in a variable.