Homeostasis

Question 1

Describe the structural hierarchy of the human body

Answer 1

Cells - basic structural and functional unit
Tissues - Aggregates of cells with a particular function
Organs - Specialised tissue with connective tissue, serves by nerves and blood vessels
Systems - A group of organs that collectively preform a function

Question 2

How much fluid is found in and out of cells?

Answer 2

70% of fluid is intracellular fluid (ICF)

and 30% is extracellular fluid (ECF)

Question 3

Why is the regulation of concentrations of ICF and ECF?

Answer 3

Because it is critical to the functioning of organelles, cells, tissues, systems and organisms

Question 4

Define homeostasis

Answer 4

Physiological control systems that maintain a relatively stable internal environment in a fluctuating environment.

Question 5

How is homeostasis maintain withing cells and between tissues/organs/systems?

Answer 5

Cells - genetics
Between tissues ect - nervous system (provides quick responses but over a short period of time)
Endocrine system (provides long response times but for a longer period of time)

Question 6

Describe the open loop control system

Answer 6

The output is not influenced by resulting conditions. For examples, epithelial cell in the gut continuously absorb glucose

Question 7

What are the the types of closed feedback

Answer 7

Negative feedback and positive feedback

Question 8

Using temperature as an explain negative feedback

Answer 8

Skin and hypothalamus receptors detect temperature increase. Effector responses begin to reduce temperature. Then receptors detect temperature change below set point, stimulates effector responses begin to reduce temperature.

Question 9

Describe negative feedback in the control of arterial blood pressure

Answer 9

Baroreceptors (strech receptors in carotid arteries and aortic arch) send a signal to solitary nucleus in medulla oblongata which identifies changes in blood pressure. Heart and blood vessels respond causing a rise or fall in blood pressure which gets feedback to baroreceptors.

Question 10

What is gain?

Answer 10

It is correction over error. Gain varies in different systems, the higher the number, the more effective the system.

Question 11

What is a feature of positive feedback?

Answer 11

It is found less often physiologically

Question 12

Describe positive feedback using oxytocin as an example

Answer 12

Uterine contractions and pushing of the feotus against the cervix stimulates the release of oxytocin from the pituitary through endoneurocrine reflex. This increases uterine responsiveness to oxytoxin

Question 13

How is positive feedback stopped?

Answer 13

When the cycle is broken by removing the stimulus

Question 14

Describe the basics of positive and negative feedback

Answer 14

Controller - controlled component - output - sensor - feedback - controller

Question 15

Describe the feed-forward control system and give an example

Answer 15

A response is generate in anticipation of a change. for example the sight, thought or smell of food induces a response from the GI tract.
Results in ingesta broken down and nutrients absorbed and ready for immediate use or storage. The overall result means that nutrient levels are controlled.

Question 16

Name some normal rhythms that have a variable set point across the day.

Answer 16

Body Temp, Systolic blood pressure and cortisol hormone secretion.

Question 17

Where are the main locations of the receptors responsible for controlling body temperature?

Answer 17

Skin for superficial receptors. Deep receptors are found in the spinal cord, abdominal viscera and great veins of the upper abdomen and throax

Question 18

Where is the location of the temperature integrating centre?

Answer 18

The hypothalamus

Question 19

What are the main effectors involved in thermal regulation

Answer 19

3 main effectors: Vasomotor, metabloic effectors and sweat glands.

To decrease temperature - Vasodilation, sweating and decrease in the mechanisms that cause heat production
To increase body temperature - Vasoconstriction, piloerection and heat production by metabolic systems increases.

Question 20

What adult body temperature is an indication of a fever?

Answer 20

Any temperature over 37.5 degrees Celsius

Question 21

What differentiates fever from other types of hyperthermia

Answer 21

Fever is having an increased temperature due to an increase in the bodies temperature set point. Hyperthermia does not involve an increase in the set point.

Question 22

What is a pyrogen?

Answer 22

A protein/substance that causes the body temperature set point to increase. Most common is a toxins released from lipopolysaccharides.

Question 23

Release of what class of molecules is caused by pyrogens in humans?

Answer 23

Prostaglandins

Question 24

Does a fever confer any advantage when fighting infection?

Answer 24

An increased body temperature can improve the efficiency of lymphocytes, thus improving your immune system.