1.9 - Cytoskeleton and Homeostasis

Question 1

What are the main components of the cytoskeleton?

Answer 1

• Microtubules (big)
• Intermediate filaments (medium)
• Microfilaments (small)
• All hollow tubes/tunnels

Question 2

What are microtubules?

Answer 2

Microtubules are highways which allow movements of vesicles, organelles, and chromosome movements in cell division. They also help to maintain cell shape

Question 3

What are centrioles/centrosomes

Answer 3

Centrioles are cylindrical, barrel-shaped organelles used to help generate and organize the cell’s microtubules. They exist within the centrosome

Centrosomes are cellular structures involved in the process of cell division

Question 4

What are flagella/scilia?

Answer 4

Flagella/scilia are the end/tail-like structure on sperm that allow them to swim

• This same motor moves up and down on microtubules to help them move

Question 5

What are microfilaments?

Answer 5

Microfilaments (sometimes called actin filaments) are formed using two strands of a protein called actin

They are responsible for muscles contracting, and are responsible for amoeboid movements (which obviously only happens in amoebas)

Question 6

What are intermediate filaments?

Answer 6

Intermediate filaments are the cell’s circus ropes. They are responsible for anchoring organelles to prevent them from moving, and are responsible for maintaing cell shape.

Question 7

Where are intermediate filaments mostly found?

Answer 7

Intermediate filaments are mostly found in the intestines. The circus ropes anchor epithelial cells to make sure you do not shit out your intestinal lining

Question 8

What does extracellular matrix mean?

Answer 8

Extracellular matrix refers to anything outside the cell

Question 9

What is homeostasis?

Answer 9

Homeostasis refers to the fact that all living things have ideal/perfect set points (ex: temperature; we should be 37°C, not too high, not too low)

Homeostasis tries to reset your system when you are outside the normal range (ex: hypo/hyperthermia

Question 10

What are the steps in homeostasis?

Answer 10

1. Stimulus/stressor disrupts homeostasis, which increases/decreases the controlled condition. This is monitored by
2. The receptors. From there,
3. An afferent conductor sends the information to a control centre.
4. The control centre processes the information received and decides what to do about it
5. The control centre sends a signal through an efferent conductor to arrive at an effector where the appropriate response takes place

Question 11

What is the control centre?

Answer 11

The control centre is the brain and spinal cord, where nervous system-related messages are sent

Question 12

What are the conductors?

Answer 12

The conductors are nerves which send impulses/messages to the brain

Question 13

What are afferent conductors?

Answer 13

Afferent conductors are messenger neurons who send the message to the central nervous system (brain)

Question 14

What are efferent conductors?

Answer 14

Efferent conductors are glands who receive messages from the central nervous system (brain) about how to resolve a deviation in homeostasis. They then carry out this fix.

Question 15

What is negative feedback?

Answer 15

Negative feedback is when homeostatic mechanisms counter the stressor’s effect (ex: increase body temperature when body is cold)

• This is the typical type of feedback of homeostasis: if a stimulus causes an increase, the response is a decrease and vice versa

Question 16

What is positive feedback?

Answer 16

Positive feedback is when homeostatic mechanisms agree with the stressor’s effect (ex: increase pain when body reports feeling pain).

• This may seem counter-intuitive, but it is typically used to help accelerate a response in order to overcome a stressor: if a stimulus causes an increase, the response is an increase and vice versa

Question 17

What are the principal afferent/efferent connductors of the body?

Answer 17

The nervous system and the endocrine system are the principal aff/efferent conductors of the body

• The effectors used include many other systems

Question 18

Which of the forms of feedback is more common in the body?

Answer 18

Negative feedback is MUCH more common. Positive feedback is rare in biological systems.

An example of positive feedback is childbirth, which is sped up with positive feedback: the body reports feeling pain because of uterine contractions. The brain receives this message, and responds by releasing Oxytocin, which causes more uterine contractions. This helps to push the baby out sooner, thus ending the pain

Question 19

How do organ systems maintain homeostasis in the body?

Answer 19

Organ systems maintain homeostasis in the body by working together.

Ex: the concentration of oxygen and carbon dioxided is controlled by 4 different bodily systems: respiratory, circulatory, nervous, and musculatory systems