Hormonal (Endocrine) Systems

Question 1

What is hypothermia?

Answer 1

Hypothermia is a condition in which the core body temperature falls significantly below normal.

Question 2

What is the body’s natural core temperature?

Answer 2

Around 37 degrees

Question 3

At what temperature does shivering stop during hypothermia?

Answer 3

Between 30-32 degrees, the body also stops producing more heat during this stage

Question 4

What temperature does the heart stop beating during hypothermia?

Answer 4

The body would enter a coma and the heart would cease to beat in between 21-28 degrees

Question 5

What are hormones?

Answer 5

It is a chemical produced in animals in the endocrine gland that is released into and transported via the bloodstream to other parts of the body where they act.

Question 6

What is the endocrine system?

Answer 6

It is a system of ductless glands that produce hormones and release them directly into the blood stream.

Question 7

What is the external environment?

Answer 7

It is the environment outside an organism

Question 8

What is the internal environment?

Answer 8

It is the fluid surrounding living cells within a multicellular organism.

Question 9

Define tissue fluid

Answer 9

Tissue fluid is the liquid that surrounds and baths the membranes of nearly all cells.

Question 10

What is plasma?

Answer 10

Plasma is the liquid part of the blood in which blood cells are suspended.

Question 11

Define extracellular fluid

Answer 11

It is also called tissue fluid, it is the fluids that surround and bathe the membranes of nearly all cells.

Question 12

What is intracellular fluid?

Answer 12

Intracellular fluid is the fluids that are contained inside cells, for example cytosol is an intracellular fluid.

Question 13

List three substances that can move between the internal fluid compartments of the body.

Answer 13

• Glucose
• Oxygen
• Carbon dioxide

Question 14

Define homeostasis.

Answer 14

Homeostasis is a condition of a relatively stable internal environment maintained within narrow limits.

Question 15

What two systems contribute to homeostasis?

Answer 15

• Endocrine system

* Nervous system

Question 16

What is the negative feedback system?

Answer 16

If a change is detected in a variable, such as a drop in body temperature, an action occurs to produce a change in the opposite direction, which in this case is a rise in body temperature.

Question 17

What variables are controlled by the negative feedback system?

Answer 17

• Nutrients
• Temperature
• Water
• Blood volume
• Blood pressure
• Oxygen
• pH (hydrogen ion concentration)
• Red blood cells
• Carbon dioxide

Question 18

How does the nervous system contribute to homeostasis?

Answer 18

The nervous system receives and transmits information about both the external and internal environment. Transmits electrical impulses to body cells that respond in various ways.

Question 19

How does the endocrine system contribute to homeostasis?

Answer 19

The endocrine system produces hormones that are secreted directly into the bloodstream and transported throughout the body where they regulate cell activities.

Question 20

How does the respiratory system contribute to homeostasis?

Answer 20

Obtains oxygen from air and eliminates carbon dioxide, which is a waste product of metabolism in cells. It assists in regulation of pH through removal of carbon dioxide.

Question 21

How does the circulatory system contribute to homeostasis?

Answer 21

Transports oxygen to cells and carbon dioxide away from cells, and transports hormones, wastes, nutrients such as glucose, amino acids and fatty acids throughout the body.

Question 22

How does the digestive system contribute to homeostasis?

Answer 22

Obtains nutrients, water and salts from food that is eaten. These are transferred to the bloodstream and lymph vessels in the intestinal wall. In ingested residue is eliminated.

Question 23

How does the excretory system contribute to homeostasis?

Answer 23

It removes wastes such as urea, excess water, salt and other ions from the blood and eliminated them from the body in form of urine. It’s also important for regulating pH.

Question 24

How does the integumentary (skin) system contribute to homeostasis?

Answer 24

It is a barrier between the body and external environment. Evaporation of sweat is important in temperature regulation. It also inhibits the entry of micro organisms.

Question 25

What systems of the body contribute to homeostasis?

Answer 25

• Nervous system
• Endocrine system
• Respiratory system
• Circulatory system
• Digestive system
• Excretory system
• Integumentary system

Question 26

Why is nutrient concentration important for homeostasis?

Answer 26

Nutrients are required by all cells as a source of energy and also for repair and growth. Glucose is a major nutrient and it’s blood level is typically maintained within narrow limits, for diabetics significant change from the normal level has an adverse effect.

Question 27

How does temperature effect homeostasis?

Answer 27

The core temperature in humans is maintained within very narrow limits. Fluctuations from the specific temperature can cause severe problems and may become life threatening.

Question 28

What are the two interrelated stages of homeostasis? Also known as negative feedback.

Answer 28

Stage one: detecting change from a stable state

Stage two: counteracting change

Question 29

What happens in the first stage of detecting change in homeostasis?

Answer 29

In detecting change from a stable state, a sensor of some kind detects a change in a specific variable from the desired stable level of the variable. The fact that there has been an undesirable change is then transmitted to the next part of the control system.

Question 30

What happens in the second stage of counteracting change in homeostasis?

Answer 30

In the second stage of counteracting change, an effector receives a message that an undesirable change must be counteracted and the variable restored to its desired level.
This is also known as negative feedback.

Question 31

What hormones does the pancreas produce that controls blood glucose?

Answer 31

• Insulin- which controls the uptake of glucose by cells from the blood
• Glucagon- which acts on the liver to release more glucose into the bloodstream

Question 32

If the blood glucose level falls below normal what are the two responses the pancreas makes?

Answer 32

1. Some cells, called alpha cells, increase their productive of the hormone glucagon, which acts on the liver to convert stored glycogen to glucose and then glucose passes from the liver to the bloodstream.
2. Other cells, called beta cells, decrease their production or insulin. The less insulin in the blood results in less glucose being taken from the blood by cells of the body.

If the blood glucose level was two high, the alpha and beta cells would just do the opposite.

Question 33

What is positive feedback?

Answer 33

Positive feedback systems involve a situation in which a hormone produced by a gland acts in the same gland and stimulates it to produce even more of the hormone.
E.g. Oxytocin, is produced by the posterior pituitary gland during childbirth, once the birthing process begins, oxytocin stimulates uterine contractions that help push the baby out of the uterus.

Question 34

What are signalling molecules?

Answer 34

They are molecules that carry signals or messages from one cell to another; can be hormonal, neurohormonal, etc.

Question 35

What are the three different kinds of hormones?

Answer 35

• Amino acid derivatives
• Steroid hormones
• Protein hormones and peptide hormones

Question 36

What is the chemical nature and features of a amino acid derivative hormone?

Answer 36

They are small molecules structurally related to a simple amino acid; for example, thyroid gland hormones are derived from tyrosine.
They are also water soluble, travel through the bloodstream but are unable to pass through cell membranes.

Question 37

What is the chemical nature and features of a steroid hormone?

Answer 37

They are structurally related to cholesterol; examples are testosterone and progesterone, that are produced in the reproductive organs.
They are transported in the blood by carrier proteins and are able to pass through cell membranes.

Question 38

What are is the chemical nature and features of peptide and protein hormones?

Answer 38

They are chains of different numbers of amino acids. Insulin from the pancreas is an example of a peptide hormone. Thyroid stimulating hormone (TSH) from the pituitary gland is a protein hormone.
They are water soluble, they travel through the blood stream but are unable to pass through cell membranes.

Question 39

Why can steroid hormones pass through cell membranes?

Answer 39

Because they have a lipid base, therefore are lipophici can and are insoluble in water, however because of their lipophilic nature, they require a carrier protein for transport via the blood stream.

Question 40

Why can peptide and protein hormones travel through the bloodstream but not cell membranes?

Answer 40

Because they are hydrophilic, therefore they require no assistance to travel in the bloodstream. However, because of their hydrophilic nature, they are unable to pass through phospholipid membranes without assistance. They need require the presence of a second messenger molecule, such as a G protein to transmit their message from the surface of the membrane receptor into the cytosol.