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Biosciences 1 > Body and Cell Organisation > Flashcards

Body and Cell Organisation Flashcards

1
Q

Define homeostasis

A

The maintenance of a constant internal environment (must be maintained for normal body functioning and to sustain life)

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2
Q

Define homeostatic imbalance

A

A disturbance in homeostasis resulting in ill health

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3
Q

Explain the process of homeostasis

A
  • Imbalance in homeostasis (stimulus)
  • Change is detected and received by the receptor
  • Input is sent via the AFFERENT pathway
  • Received by control centre
  • Output sent via efferent pathway
  • Received by effector
  • Causes a response to change
  • Imbalance is corrected
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4
Q

Outline and explain negative feedback

A

Negative feedback shuts off the original stimulus, or reduces its intensity and brings it back to within normal limits

For example, a household thermostat acts like a ‘receptor,’ it detects room temperature.
The boiler acts as a ‘control centre’ as it initiates a response depending on information received from the thermostat
-The radiators act like ‘effectors’ and increase room temperature to within acceptable limits

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5
Q

Outline and explain positive feedback

A

Positive feedback increases the original stimulus to push to variable farther

This rarely happens. Two examples of this are blood clotting and childbirth

The body does not try to restore homeostasis until the stimulus has gone, i.e. baby is born or bleeding has stopped

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6
Q

Name the 5 cavities of the body

A 
Cranial Cavity
Spinal Canal (cavity)
(BOTH CONTAINED IN DORSAL BODY CAVITY)
Thoracic Cavity
Abdominal Cavity
Pelvic Cavity
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7
Q

What does the cranial cavity contain?

A

The brain, the meninges (covering) and CFS

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8
Q

What does the spinal cavity contain?

A

The spinal cord runs from the brain down through the vertebral column within the spinal cavity

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9
Q

What does the thoracic cavity contain?

A

The heart and the lungs. The thoracic and abdominal cavity are separated by the diaphragm

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10
Q

What does the abdominal cavity contain?

10 items

A

Liver, gall bladder, stomach, small intestine, large intestine, spleen, kidneys, pancreas, large blood vessels

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11
Q

What are the two different types of cell?

A

Eukaryotes (contain a nucleus)

Prokaryotes

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12
Q

What are the two main body fluid compartments?

A

Intracellular (ICF) (inside)= 66% of body fluid

Extracellular (ECF) (outside)= 33% of body fluid

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13
Q

Name the subdivisions of ECF

A
  1. Interstitial fluid (80% of ECF)

2. Plasma (20% of ECF)

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14
Q

What is the function of the plasma (cell) membrane?

A

(most important part of the cell)

  • Separates intracellular and extracellular fluid
  • Controls the transport of materials in and out of the cell
  • Holds receptors for hormones and other active substances
  • Selectively permeable
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15
Q

What is the structure of the phospholipid membrane?

A
  • Made of 2 layers of phospholipids (phospholipid bilayer)
  • Hydrophilic (water loving) heads in contact with intra- and extracellular fluid
  • Hydrophobic (water hating) tails within bi-layer are not in contact with water
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16
Q

What are receptors?

A

Signalling molecules- cell activity can be changed by chemical messengers which attach to receptors on the cell membrane
Receptors on sensory nerve endings can also recognise signals such as pressure and temperature
Nerves convey this information to the brain so we become aware of the situation

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17
Q

Explain the movement of substances across the plasma membrane

A
  • Substances that are allowed in enter via diffusion and osmosis
  • Only fat-soluble substances can diffuse freely across the phospholipid bilayer
18
Q

What is diffusion?

A

Movement of solutes from a high concentration to low concentration
Movement of solutes continues until both solutions are of equal strength

19
Q

Give an example of diffusion

A

Gas exchange in the lungs occurs through diffusion.
High concentrations of oxygen move out of the lungs into blood to balance concentration
Carbon dioxide does the opposite- it moves from the blood into the lungs

20
Q

What is osmosis?

A

Movement of water molecules from an area of low solute (high water) concentration to high solute (low water) concentration until equilibrium is achieved

21
Q

What is facilitated transport?

A

The diffusion of materials across the plasma membrane with the help of membrane proteins.
Channels have to change shape so diffusion is controlled, these channels can close but diffusion is still down a concentration gradient

22
Q

What is active transport?

A

Where some substances need to be diffused against the concentration gradient (area of low to high concentration), which requires energy in the form of ATP
Active transport enables cells to regulate what enters and what leaves

23
Q

What is the cytoplasm?

A

The ground substance in which cellular components are found. Consists of thick semi-transparent fluid within which organelles are suspended

24
Q

What is the composition of cytoplasm?

A

75% water
Dissolved substances e.g. electrolytes (charged particles)
Proteins

25
Q

What is the function of the cytoplasm?

A
  • Site where most chemical reactions occur and where new substances are synthesized for cell use
  • Facilitates excretion of waste from cell
26
Q

What is the definition of organelles?

A

‘little organs’ (specialised structures found in the cell)

27
Q

What is the structure of the nucleus?

A
  • Largest of the organelles- centre of the cell
  • Spherical in shape
  • Membrane (nuclear envelope)- same structure as plasma membrane
  • Contains jelly-like nucleoplasm
  • Centrally placed body (nucleolus)
28
Q

What is the function of the nucleus?

A

Contains chromosomes (46 in somatic cells) and genetic mater, deoxyribonucleic acid (DNA) and ribonucleic acid (RNA)

29
Q

What are the endoplasmic reticulum?

A

A network of channels running through the entire cytoplasm

30
Q

Describe the structure and function of the rough ER

A

Ribosomes on the outer surface, giving a rough (studded) appearance
Used to synthesise proteins

31
Q

Describe the structure and function of the smooth endoplasmic reticulum

A

Long network of folded, tube-like structures Synthesis of carbohydrates and lipids

32
Q

Describe the structure of the golgi apparatus

A

Consists of 4-8 of flattened bag-like channels stacked one on top of the other
Located near the nucleus and in places is connected to the endoplasmic reticulum

33
Q

Describe the function of the golgi apparatus

A

Packages products into vesicles that are stored and when needed they move to the plasma membrane when they are released

34
Q

Describe the structure of the mitochondria

A

Small structures that appear throughout the cytoplasm
Consist of a double-layer membrane, similarly to the plasma membrane
Outer membrane covers the organelle and contains it like a skin
Inner membrane folds over many times and creates layered structures called cristae
The fluid contained in the mitochondria is called the matrix.

35
Q

Describe the function of the mitochondria

A

The powerhouse of the cell where ATP is synthesised

36
Q

Describe the structure of lysosomes

A

Membranous walls
Shape and size change with the stage of their activity, e.g. when inactive they take on the appearance of small sacks
Contain various kinds of enzymes

37
Q

Describe the function of lysosomes

A

The enzymes protect the cell, i.e. destroy bacteria that enter the cell. White blood cells contain large numbers of lysosomes

38
Q

What is the structure of centrioles?

A

Spherical structures located near the nucleus

Tiny cylinders that consist of 9 bundles of micro-tubules in each bundle

39
Q

What is the function of centrioles?

A

Form the spindle that appears during cell division (mitosis) (mature nerve cells do not have centrioles)

40
Q

What are the main components of a cell?

A

Cell membrane
Organelles
Cytoplasm

41
Q

What is cytosol?

A

Liquid found within the cells. Constitutes most of the intracellular fluid (ICF). Separated into compartments by membranes

Biosciences 1 (6 decks)

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