Human Physiology: Homeostasis and Nutrients

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Questions and Answers

What role do the kidneys play in the regulation of extracellular fluid?

Provide motility for protection

Regulate the concentration of glucose

Regulate concentrations of hydrogen, sodium, potassium, and other ions (correct)

Control blood supply through circulation

What is the primary mechanism that biological control systems use to maintain homeostasis?

Positive feedback loops

Randomized feedback

Negative feedback loops (correct)

None of the above

Which component of a negative feedback system compares sensor input to a set point?

Controller (correct)

Sensor

Stimulus

Effector

What does vasodilation refer to in the context of blood pressure regulation?

Expansion of the arterioles Signup and view all the answers

In a feedback loop, what initiates the sequence of changes to maintain homeostasis?

Stimulus Signup and view all the answers

What can be an example of a factor modulated by negative feedback mechanisms in the body?

Blood pressure Signup and view all the answers

Which of the following is NOT a component of a negative feedback system?

Effectiveness Signup and view all the answers

What physiological actions can the body take to control blood pressure through negative feedback?

Modify heart rate and control blood vessel diameter Signup and view all the answers

Which part of the nervous system is responsible for detecting the state of the body or surroundings?

Sensory portion Signup and view all the answers

What is the primary function of hormones in the body?

Regulate cellular functions Signup and view all the answers

Which system is responsible for the automatic control of body parameters like temperature and blood pressure?

Closed control system Signup and view all the answers

What role does the brain play in the central nervous system?

It generates and stores information Signup and view all the answers

Which of the following is not considered a major part of the nervous system?

Endocrine system Signup and view all the answers

What is the primary function of the autonomic nervous system?

To manage internal organ functions Signup and view all the answers

Which system works in conjunction with the respiratory system to regulate CO2 concentration?

Nervous system Signup and view all the answers

Which of the following is an example of open-loop control in the body?

Manual drug administration Signup and view all the answers

What role does the integrating center play in homeostasis?

It compares the stimulus to the normal level of the variable. Signup and view all the answers

What happens when a response is required in maintaining homeostasis?

A message is sent via an efferent pathway to the effector organ. Signup and view all the answers

What is one of the primary functions of the liver in nutrient handling?

Changing the chemical composition of absorbed substances. Signup and view all the answers

How does the respiratory system contribute to the removal of metabolic end products?

It exchanges CO2 for O2 in the alveoli. Signup and view all the answers

What is a function of the musculoskeletal system in relation to nutrition?

It assists in obtaining food and provides protection. Signup and view all the answers

What substances do the kidneys primarily remove from the plasma?

End products of cellular metabolism like urea and uric acid. Signup and view all the answers

Which of the following best describes the response of effectors in the body?

They produce actions to move values toward the set point. Signup and view all the answers

What type of nutrients does the gastrointestinal tract primarily absorb?

Carbohydrates, fatty acids, and amino acids. Signup and view all the answers

What is one of the consequences of decreased blood flow in the context of hemorrhage?

Increased accumulation of lactic acid and hydrogen ions Signup and view all the answers

Which mechanism illustrates a positive feedback system during nerve impulse propagation?

Opening of voltage-gated Na+ channels leading to more depolarization Signup and view all the answers

How does childbirth serve as an example of positive feedback?

Uterine contractions stimulate cervical stretch for stronger contractions Signup and view all the answers

What is the primary effect of positive feedback in the case of hemorrhage?

Reduction of cardiac output Signup and view all the answers

What are the effects of increased vasodilator metabolites during decreased blood flow?

Reduced peripheral resistance leading to lower blood pressure Signup and view all the answers

What role do pressure receptors play in blood pressure regulation?

They detect changes in blood pressure and send signals to the controller. Signup and view all the answers

How does the body respond to an increase in blood pressure?

By decreasing heart rate and inducing vasodilation. Signup and view all the answers

What mechanism does the pancreas use to regulate blood sugar levels?

Secreting insulin in response to high blood sugar levels. Signup and view all the answers

Which type of animals are classified as homeotherms?

Mammals and birds that maintain a constant body temperature. Signup and view all the answers

What happens to blood vessels when blood pressure decreases?

Vessels constrict to help increase blood pressure back to baseline. Signup and view all the answers

What is the primary function of the thermoregulatory centre in the hypothalamus?

To maintain a constant body temperature. Signup and view all the answers

What could cause oscillations in a homeostatic system?

The nature of negative feedback control itself. Signup and view all the answers

Which of the following statements about poikilotherms is true?

They can have varying blood temperatures depending on environmental conditions. Signup and view all the answers

Study Notes

Homeostasis

The integrating center compares the stimulus to the normal level of the variable – the “set point”.
A message is sent via an efferent pathway to the effector organ if a response is required.
The effector produces a response that moves the value of the variable back towards the set point.
Responses include altering breathing, heart rate, blood pressure, vasoconstricting or vasodilating, eating, drinking, and secreting.

Origin of Nutrients in the Extracellular Fluid

The respiratory system allows the blood to pick up oxygen in the alveoli.
The gastrointestinal tract absorbs resolved nutrients from ingested food into the extracellular fluid.
The liver changes the chemical composition of substances absorbed from the gastrointestinal tract to more usable forms.
Other tissues, like fat cells, kidneys, and endocrine glands, help modify or store absorbed substances.
The musculoskeletal system allows the body to move to obtain food required for nutrition and provides motility for protection.

Removal of Metabolic End Products

The lungs release CO2 from the blood into the alveoli.
The kidneys remove most substances from the plasma that are not needed by the cells, including urea and uric acid.

Regulation of Body Functions

The nervous system is composed of the sensory portion, the central nervous system, and the motor output portion.
The central nervous system is composed of the brain and spinal cord.
The autonomic system controls many functions of the internal organs.
The hormonal system secretes hormones that help regulate cellular functions.
Reproduction maintains static conditions by generating new beings.

Control Systems of the Body

Control systems can be open-loop or closed-loop.
Open-loop control requires manual adjustment.
Closed-loop control is automatically controlled by the body control systems.

Examples of Control Systems

The genetic system controls intracellular and extracellular functions.
The respiratory system regulates CO2 concentration in the extracellular fluid.
The liver and pancreas regulate glucose concentration in the extracellular fluid.
The kidneys regulate concentrations of hydrogen, sodium, potassium, phosphate, and other ions.
The heart controls blood supply.
The musculoskeletal system provides motility for protection.
The gastrointestinal system maintains nutrients.

Characteristics of Control Systems

Biological systems operate on a mechanism of inputs and outputs.
Feedback loops are crucial for maintaining homeostasis.
Control systems are characterized by negative feedback and positive feedback.

Negative Feedback

Negative feedback returns a factor toward a certain mean value, maintaining homeostasis.
Most control processes in the body act by negative feedback.
Negative feedback systems contain:
- Stimulus
- Sensor
- Controller
- Effector

Examples of Negative Feedback

Blood pressure homeostasis:
- Stimulus: Changes in blood pressure
- Sensor: Pressure receptors in the aorta and carotid arteries
- Controller: Nervous system
- Effector: Heart and blood vessels
Blood glucose homeostasis:
- Stimulus: Increase in blood sugar
- Sensor: Receptors in the body
- Controller: Pancreas
- Effector: Insulin release
Temperature homeostasis:
- Stimulus: Change in body temperature
- Sensor: Thermoreceptors in the hypothalamus
- Controller: Hypothalamus
- Effector: Mechanisms to increase or decrease heat production or loss

Positive Feedback

Positive feedback amplifies the system.
While some positive feedback systems can be harmful, they are also crucial in certain situations, such as nerve impulse propagation and childbirth.

Examples of Positive Feedback

Nerve impulse propagation:
- Initial membrane depolarization opens Na+ channels, leading to further depolarization and activation of more Na+ channels.
Childbirth:
- Stretch of the cervix during labor triggers more intense uterine contractions, leading to further cervical stretch and more intense contractions.

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Description

Test your knowledge on the concepts of homeostasis and the origin of nutrients in the extracellular fluid. This quiz covers how the body maintains stable internal conditions and how different systems facilitate nutrient absorption and utilization. Challenge yourself to understand this vital aspect of human physiology.