Lecture 11- Homeostasis Flashcards

You may prefer our related Brainscape-certified flashcards:
1
Q

What is homeostasis?

A

The steady state of physiological conditions in the body

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
2
Q

True or False: All living things regulate internal conditions in some way.

A

True. Homeostasis is a basic characteristic of living things.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
3
Q

Negative Feedback regulation

A

Response to a stimulus reduces stimulus.

This is the most common type and works to oppose the initial change. Imagine your room getting too hot. The sensor detects the rise in temperature, and the control center tells the effectors (sweat glands) to kick in, cooling you down and bringing the temperature back to the set point. Examples include thermoregulation, blood sugar regulation, and blood pressure regulation.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
4
Q

Which type of feedback regulation is more common?

A

Negative feedback (reduce stimulus)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
5
Q

Positive Feedback regulation

A

Response to stimulus amplifies stimulus- less common.

This less common type amplifies the initial change. One example is childbirth. As the baby pushes down, it triggers the release of a hormone that causes stronger contractions, further pushing the baby down. This positive loop continues until birth, then stops with the removal of the stimulus (the baby),

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
6
Q

Osmoregulation

A

The process by which organisms manage their internal water and salt balance. It’s essentially all about keeping the right amount of water and electrolytes in their cells and fluids to function properly.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
7
Q

Osmoregulation/maintaining homeostasis- Paramecium

A

Paramecium is a unicellular protist (SAR clade) and generally aquatic (freshwater). The solute inside the cell is greater than the outside (outside the cell is a hypotonic environment). Due to osmosis, water naturally moves from an area of low solute concentration (freshwater) to an area of high solute concentration (the paramecium cell). This can cause the paramecium to take in too much water. To remedy this, the paramecium has a CONTRACTILE VACUOLE which is an organelle for osmoregulation. The contractile vacuole pumps water out to maintain water balance and prevent lysis (bursting) of the cell.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
8
Q

What is the organelle for osmoregulation and what does it do?

A

Contractile vacuole, pumps water out to maintain water balance and prevent lysis.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
9
Q

Osmoregulation/maintaining homeostasis- Jellyfish

A

Phylum Cnidaria. Disploblastic development -> 2 adult tissue layers. No dedicated circulatory system- all water movement via diffusion.
Diffusion= molecules move from an area of high concentration to an area of low concentration. Jellyfish passively matches the surrounding salinity to avoid major water imbalances.
“Flat” morphology

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
10
Q

Osmoregulation/maintaining homeostasis- Humans

A

Terrestrial Animals.
Animals first evolved in oceans. Take our marine environment with us on the inside. Have to keep it and maintain conditions- gases, pH, etc.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
11
Q

Terrestrial Adaptations for maintaining homeostasis

A

Reproduction/development- Amniotic sac
Water balance- Scales/skin, Excretory system

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
12
Q

Homeostasis for smaller, aquatic/marine vs. larger, terrestrial

A

Smaller, aquatic/marine- often osmosis/diffusion
Larger, terrestrial- dedicated transport tissues to prevent desiccation, maintain pH, solute

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
13
Q

Homeostasis in Animals- basic constraints

A

Body size/shape limited by physical laws
Strength, diffusion, movement, heat exchange also limited by physical laws

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
14
Q

Example: Shape of Swimming Animals

A

Problem: Limited by water, denser, more viscous than air
Solution:
-> smooth body
-> streamlined shape
Diverse organisms, same environment (seal, penguin, tuna etc)
Convergent evolution- selection favors similar adaptations

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
15
Q

Explain the exchange animals have with their environment.

A

Animals are not closed systems. They exchange nutrients, gases, and waste with their environment. These materials are typically transported as dissolved materials in H2O across the cell membrane. The way animals exchange with their environment affects their body plan.
(Think of coelomates vs. acoelomates. Coelomates are more complex and have space for internal organs. This facilitates efficient exchange and a well-developed circulatory system to transport materials throughout the body, which enables larger body sizes and increased complexity. Aceolomates lack a coelom, a fluid-filled body cavity. Due to the absence of a coelom, most of their cells are directly in contact with the environment, limiting their body size.)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
16
Q

Cell

A

Basic unit

17
Q

Tissues

A

Groups of cell with similar structure and function

18
Q

4 Main types of tissue in animals

A
  • Epithelial
  • Connective
  • Muscle
  • Nervous
19
Q

Organs

A

Different tissues organized into functional unit

20
Q

Organ system

A

Organs that work together

21
Q

Do all organs do transport and exchange?

A

NO

22
Q

Homeostasis Processes

A

Can be internal- e.g. shivering
Or external- often involve exchange
Something moves body -> environment or environment -> body. E.g. basking, sweating.

23
Q

2 strategies for maintenance of homeostasis

A

Regulator and Conformer
Many animals will regulate some conditions, conform to others.

24
Q

What is a regulator?

A

Uses internal mechanisms to control internal conditions, independent of external conditions.

25
Q

What is a conformer?

A

Allows internal environment to vary with external changes.

26
Q

Adaptations for Exchange

A
  • Branching- Structures that divide into smaller branches, increasing surface area.
  • Folding- Creating internal folds or pockets within an organ or structure, increases surface area within a confined space.
  • Internal fluids- Act as a transport medium for essential materials throughout the body (blood, lymph, cytoplasm).
27
Q

How do regulators maintain homeostasis?

A

Set point- Variables maintained at/near specific value
OR
Normal range- Variable has upper and lower limit
Kept at set point or within range via negative feedback

28
Q

All tissues, organs, organ systems must work together. What 2 major systems coordinate responses to stimuli?

A

Endocrine- signaling by hormones.
Nervous- signaling by nerve impulse.

29
Q

Endocrine Regulation

A

Involves hormones and feedback regulation (mostly negative)

Hormone: Long-distance chemical signals
- Released by specific cells
- Travel through body
- Cause physiological response

30
Q

What two hormones are involved in blood glucose regulation and what signals do they give?

A

Insulin -> store sugar
Glucagon -> release sugar

31
Q

In blood glucose regulation, the hormone insulin causes the liver to store sugar, while the hormone glucagon causes the liver to release sugar. This is an example of ______________.

A

Antagonistic- opposite effects

32
Q

In blood glucose regulation, the __________ makes hormones and the ____________ stores glycogen.

A

In blood glucose regulation, the pancreas makes hormones and the liver stores glycogen.

33
Q

Explain the steps of blood glucose regulation.

A
  1. Blood glucose level rises.
  2. The pancreas releases insulin.
  3. In response to insulin, target cells take up glucose and the liver converts glucose to glycogen (storage form of glucose).
  4. Blood glucose level falls.
  5. The pancreas releases glucagon.
  6. In response to glucagon, the liver breaks down glycogen and releases glucose into the blood.
  7. Blood glucose level rises.