Cells Flashcards
Cranial Cavity contains:
- the brain
- meninges (the covering)
- spinal cord
Where does the spinal cord run?
from the brain down through vertebral column within the spinal cavity
Thoracic Cavity contains:
- heart
- lungs
Abdominal Cavity (from front) contains:
- liver
- gall bladder
- stomach
- small intestine
- large intestine
What are the Thoracic and Abdominal cavities separated by?
The diaphragm
Abdominal Cavity (from back) contains:
- spleen
- kidneys
- pancreas
- large blood vessels
Pelvic Cavity contains:
- bladder
- urethra
- bowel
- female = ovaries, uterus, vagina
What are the two types of cells? (not all found in the human body)
1 - Eukaryotes
2 - Prokaryotes
Eukaryotes contains:
membrane bound organelles such as nucleus.
Examples of eukaryote cells:
- human cells
- plant cells
- fungi
What do Prokaryotes cells not contain? example?
They are cells that do not contain a nucleus or membrane bound organelle.
ie. bacteria
What two types of cells does the human body contain?
1 - somatic - body cell
2 - germ - sex cell
What does a somatic cells contain?
46 chromosomes
What does a germ cell contain?
23 chromosomes
- sperm in male
- ovum in female
What does a chromosome do?
Carries genetic information.
The structure of a ‘typical’ cell is divided into 4 parts,w which are:
1 - cytoplasm
2 - organelles
3 - plasma membrane (cell wall)
4 - interstitial (watery) fluid - intracellular + extracellular
Where’s intercellular interstitial fluid found?
within the cell membrane/wall
Where’s extracellular interstitial fluid found?
exterior to the cell membrane/wall
What are the functions of the plasma membrane?
communication and regulation
How does the plasma membrane communicate?
receptors attach to chemical messengers which alters the cell activity
How does the plasma membrane regulate activity?
the membrane and membrane channels regulate what enters and exits the cells.
This maintaining ‘internal environment’ ensuring an ideal environment for cellular activity to take place
What does the Plasma membrane consist of?
- phospholipid membrane
- receptors
- glycoproteins, glycolipids and carbohydrates
- protein channels
What does phospholipid mean?
bi-layer
Phospholipid membranes are made of two layers:
- hydrophilic
- hydrophobic
Explain the HYDROPHILIC layer of a phospholipid membrane
- water loving
- leads in contact the the interstitial fluids, both intracellular and extracellular
Explains the HYDROPHOBIC layer of phospholipid membrane
- water hating
- tails within bi-layer, not in contact with fluids
What do the glycoproteins, glycolipids and carbohydrates do within the plasma membrane?
Enable communication with other cells
What do protein channels do within the plasma membrane?
enable movement of substances across the membrane
What do receptors do? and how?
They signal molecules. Activity can change by chemical messengers which attach to receptors on the membrane.
Give an example of when receptors signal
hormone adrenaline and neurotransmitters speed up heart rate
What kind of things are recognised by receptors on nerve endings?
signals such as pressure and temperature
What do nerves do?
Nerves convey information to the brain so we’re aware of a situation
Define the plasma membrane
A thin wall that separates one cell from the other cells and the environment
Substances enter the plasma membrane via 2 processes:
diffusion and osmosis
Explain diffusion
- particles distribute evenly within a solution
- movement is from high concentration to low concentration
- movement of solutes continues until both solutions are equal in strength
Explain osmosis
- movement of water molecules
- from low to high concentrate until equilibrium is achieved
Percentage of intracellular (ICF) fluid in the body
66% of body fluid
Percentage of extracellular (ECF) fluid in the body
33% of body fluid
Extracellular body fluid subdivides into 2:
1 - interstitial = 80%
2 - plasma = 20%
Membrane transport occurs by two different travel systems:
1 - facilitated transport
2 - active transport
Explain facilitated transport
channels change their shape so diffusion is controlled
Explain active transport
some substances have to be ‘pumped’ up the concentration gradient which requires energy. Active transport enables cells to regulate what enters and exits.
What is the cytoplasm?
substance in which cellular components are found
What is the cytoplasm composed of?
75% water and dissolved substances
eg. electrolytes and protein
Define electrolytes
The ionised constituents of a living cell, blood or other organic matter
What are the 2 functions of the cytoplasm?
1 - facilitates excretion (removal) of waste from cell
2 - it’s the site where most chemical reactions occur and where new substances are synthesised for cell use.
Define ‘ to synthesise substances’
The construction of complex compounds from simpler ones. It’s the process whereby many substances important to daily life are obtained.
What is an organelle?
“little organ”
specialised structure found within the cell
What roles does the organelle perform?
- growth
- maintenance
- repair
- control
Describe the nucleus
- largest of the organelles, spherical in shape
What does the nucleus contain?
Chromosomes (46 in somatic cells), and DNA, RNA (acid in ribosomes) and genetic material
Name the jelly-like fluid surrounding the nucleus
Nucleoplasm
What are ribosomes?
particles found in large numbers in cytoplasm of cell
What is the Endoplasmic Reticulum (ER)
A network of channels running through the entire cytoplasm
What is attached to the outer surface of the ER giving it a rougher appearance?
Ribosomes
Describe the 2 different types of Endoplasmic Reticulum (ER)
1 - smooth, no ribosomes
2 - rough, with ribosomes
What does the smooth surfaced ER synthesise?
carbohydrates and lipids
What does the rough surfaced ER synthesise?
protein
What does the Golgi Apparatus consist of?
tiny sacs, flattened bag-like channels stacked one on top of the other
Where is the Golgi Apparatus located?
The nucleus and other places connected to the ER
What is the function of the Golgi Apparatus?
packages products into vesicles that are stored and when needed they move to the plasma membrane where they’re released
Describe the mitochondria?
small structures that appear throughout the cytoplasm
What does the mitochondria consist of?
double-layer membrane
What is the function of Mitochondria?
They’re referred to as the ‘power houses’ of the cell because they’re the site where the cells energy (ATP) is produced
What is ATP?
ATP transports chemical energy within cells for metabolism
Describe lysosomes
- Like the ER and Golgi they have membranous walls
- shape and size changes with the stage of activity
- they contain various enzymes
What is the function of lysosomes?
It contains enzymes that protect the cell
e.g. destroys bacteria that enters
Describe centrioles
- spherical structure located near the nucleus
- tiny cylinders that consist of bundles of micro-tubules
What is the function of centrioles?
form the spindle that appears during cell division (mitosis)
What is the technical term for the cell boundary separating it from external environment?
Membrane
The membrane communicates with other cells and regulates activity via what?
the receptors
What do the organelles do for the cell?
Carries out the functions
The movement of substances in and out of cells is carried out by cell transport:
- diffusion
- facilitated transport
- active transport
For any function within the cell to take place what must happen?
The cell must import nutrients and export waste
What is the result of homeostasis?
a state of equilibrium - maintenance of a stable internal environment
Why is homeostasis important?
it must be maintained for normal functioning and to sustain life
What happens following homeostasis imbalance?
ill health
When homeostasis is at an imbalance, how does the body react?
Through the receptors, to control centre, followed by effectors allowing the stimulus to return to normal variable
Enzymes are…
Proteins that act as catalysts for biochemical reactions
Why are enzymes described as catalysts?
They speed up reactions but are never changed by it themselves therefore can be used over and over again
What does ‘homeostasis’ mean literally?
‘unchanging’
How is homeostasis maintained?
By the works of the control system
Explain diffusion using sugar in coffee
Sugar molecules heaped in the bottom of coffee that’s not been stirred will, in time, become evenly distributed throughout the coffee through diffusion.
The process is speeded up by temperature rise and/or the concentration of the substance being increased.
Explain osmosis using sugar
Imagine two solutions of sugar separated by a semipermeable membrane whose pores are too small to let the sugar through. On on side, the solution is twice as concentrated. After time, the concentration of sugar molecules will have equalised on both sides. NOT BECAUSE SUGAR MOLECULES HAVE DIFFUSED , but because osmotic pressure across the membrane ‘pulls’ water from the dilute solution into the concentrated solution. i.e. water has moved down its concentration gradient.
Osmosis refers specifically to…
diffusion of water down its concentration gradient
Osmosis proceeds until
equilibrium is reached
What’s the name of the cell that the human body develops from?
Zygote
Explain what the cytosol is
The cytoplasm holds the cytosol and organelles. The cytosol is the watery fluid part of the cytoplasm not held by an organelle.
What is/what does the nuclear pore do?
The nuclear pore is a protein-lined channel in the nuclear envelope that regulates the transportation of molecules between the nucleus and the cytoplasm.
List 5 organelles
nucleus, centrioles, mitochondria, golgi apparatus, lysosomes
What substances diffuse freely across the membrane?
small or soluble ones, e.g. oxygen
Why do some substances have to diffuse through membrane channels (facilitated diffusion)?
They’re too large to diffuse semipermeable membrane unaided. e.g. glucose and amino acids
Define semipermeable and suggest where it applies to
Permitting passage of some molecules yet hindering others
The plasma membrane
