Homeostasis Unit

Question 1

In order for the body to function properly, homeostatic mechanisms must allow the body to:

Answer 1

• regulate respiratory gases
• maintain water and salt balance
• regulate energy and nutrient supply
• maintain body temperature
• protect against pathogens
• make repairs when injured

Question 2

Definition of homeostasis

Answer 2

Homeostasis is the maintenance of constant conditions in the internal environment of an organism

Question 3

Major homeostatic set points include:

Answer 3

Body temperature: 37°C
Blood pH: 7.4
Blood glucose: 100 mg/mL
Blood pressure: 120/80

Question 4

Homeostatic systems and their descriptions:

Answer 4

Thermoregulation: maintaining the normal body temperature of 37°C
Osmoregulation: maintaining the normal blood concentration and regulating water in your body
Waste management: maintaining the control of wastes in your body

Question 5

Set point:

Answer 5

the normal homeostatic range

Question 6

Receptor:

Answer 6

detects any deviations from the set point and signals the change to the control centre along a neuron

Question 7

Control center:

Answer 7

Interprets the signal from the receptor and signals to the effector along a neuron

Question 8

Effector:

Answer 8

receives a signal from the control centre and causes a change to restore the set point

Question 9

Cells need to be able to do the following to maintain homeostasis:

Answer 9

• obtain food
• convert energy
• eliminate wastes
• reproduce
• grow and repair
• transport substances

Question 10

In order to maintain homeostasis various substances must be ______

Answer 10

In order to maintain homeostasis various substances must be transported across the cell membrane. These substances are transported into the cell for energy and out of the cell as wastes.

Question 11

The Fluid Mosaic Model of the Cell:

Answer 11

The plasma membrane is said to be fluid because components of the membrane can move around laterally (sideways). This means that the membrane can change shape and rearrange itself to suit the task! The membrane is called a mosaic because like a mosaic, it is made up of many different parts (proteins, phospholipids, antigens, etc.)

Question 12

The plasma membrane

Answer 12

It is made up of two layers of phospholipids. These phospholipids have a hydrophilic phospholipid head (water loving) and a hydrophobic fatty acid tail (water hating). These layers control the movement of water across the plasma membrane and prevent water from seeping through.

Question 13

Transport of substances into the cell can be done in two ways:

Answer 13

Actively (with help from the cell) or passively (without help from the cell)

Question 14

Passive transport:

Answer 14

Cell doesn’t do any work. Materials move from an area of high concentration to low concentration. The materials move with the concentration gradient and does not require energy.

Question 15

Diffusion:

Answer 15

Materials move from an area of high concentration to low concentration. In the cell materials will move across the membrane through specialized pores in the cell membrane.

Question 16

Osmosis:

Answer 16

Water molecules move across a selectively permeable membrane from an area of high concentration to low concentration. In the cell water will move across the membrane through specialized pores.

Question 17

Three possible concentrations for a solution:

Answer 17

Isotonic
Hypertonic
Hypotonic

Question 18

Isotonic:

Answer 18

a solution with a concentration equal to the cell

Question 19

Hypertonic:

Answer 19

a solution with a high concentration (more solute than water - concentrated). This solution has high osmotic pressure.

Question 20

Hypotonic:

Answer 20

a solution with a low concentration (less solute than water - diluted). This solution has low osmotic pressure.

Question 21

Facilitated diffusion:

Answer 21

materials move from an area of high concentration to low concentration but require the assistance of specialized carrier proteins in the plasma membrane. Each type of transport protein is specific to the substance it carries. Glucose is an example of a substance that moves across the plasma membrane in this process.

Question 22

Active transport:

Answer 22

Materials move from an area of low concentration to high concentration. Movement is against the concentration gradient. The cell needs energy in the form of ATP

Question 23

Carrier proteins or membrane:

Answer 23

Can move materials across the membrane against the concentration gradient. This process requires energy in the form of ATP

Question 24

The plasma membrane fold

Answer 24

to bring materials in the cell or eliminate materials from the cell. This can be done by endocytosis or exocytosis.

Question 25

Endocytosis:

Answer 25

Materials are "engulfed" by the cell and become enclosed in infolding of the plasma membrane that eventually form vacuoles.

Question 26

Two forms of endocytosis

Answer 26

Pinocytosis and phagocytosis

Question 27

Pinocytosis:

Answer 27

small amounts of liquids brought in ("cell drinking")

Question 28

Phagocytosis:

Answer 28

solid particles are ingested into the cell

Question 29

Exocytosis:

Answer 29

a vacuole of materials will fuse with the plasma membrane forcing contents from the cell

Question 30

Factors that influence the movement of substances across a membrane:

Answer 30

- size of molecule - concentration gradient - temperature - polarity of molecules - surface area

Question 31

Semi permeable membrane

Answer 31

As called selectively permeable membrane. a membrane that allows certain molecules to pass through by diffusion

Question 32

ATP

Answer 32

adenosine triphosphate, is the energy currency of life

Question 33

Chemoreceptor

Answer 33

a receptor stimulated by chemical means

Question 34

Hypothalamus

Answer 34

The hypothalamus controls body temperature, hunger, important aspects of parenting and attachment behaviours, thirst, fatigue, sleep, and circadian rhythms.