Cell Function And Homeostasis

Question 1

Describe the structure of the human cell

Question 2

Describe the function of each organelle in the human cell

Answer 2

Nucleus: largest organelle, contains genetic material.
Plasma Membrane: controls the passage of sibstances in and out of the cell, regulating intracellular movement.
Ribosomes: synthesises proteins from amino acids using RNA template.
Mitochondria: Aerobic respiration with 02 & ATP- batteries of the body, makes all of our energy Endoplasmic reticulum: Smooth-synthesises lipids and steroid hormones,
Rough- studded with ribosomes, packs and stores synthesised proteins
Golgi Apparatus: packages and stores proteins
Lysosomes: small membranous vesicles containing enzymes
Chromatin: helps compact DNA from longer strands into smaller packages as part of mitosis Centrioles: responsible for producing cellular spindles in mitosis as well as making microtubules

Question 3

What are the three methods of transport across the cellular membrane? Explain each process.

Answer 3

Diffusion: The movement of molecules from an area of high concentration to an area of low concentration, it’s a passive process.
Osmosis: The movement of water down the concentration gradient, it’s a passive process
Active transport: Transport of substances up a concentration gradient, it’s an active process and requires carriers.

Question 4

Name some different cell types?

Answer 4

Stem cells
Erythrocytes (red blood cells)
Leukocytes (White blood cells)
Platelets
Neurones
Neuroglial cells (myocytes)
Chondrocytes (cartilage cells

Question 5

Name some cell actions?

Answer 5

Reproduce
Nourishment (create and maintain)
Movement (energy and transport)
Excretion (get rid of waste)
Growth
Respiration

Question 6

Erythrocytes (RBC)

Answer 6

Carry oxygen
biconcave shape
No nucleus

Question 7

Kidney tubule cells

Answer 7

Control water and salt excretion

Question 8

Cardiac cells

Answer 8

Contract and control heart pumping

Question 9

Cartilage

Answer 9

Structural support in suspension

Question 10

Neurone

Answer 10

Conduct electrical impulses

Question 11

Sperm

Answer 11

Convey genetic material for reproduction

Question 12

What are the four basic tissue types ?

Answer 12

Connective tissue, epithelial tissue, muscle tissue, nervous tissue

Question 13

What is the function of connective tissue?

Answer 13

Most abundant type of cells:
Binding, supporting and protecting
Honeycomb lattice

Question 14

Describe the function of epithelial cells?

Answer 14

Form continuous sheets often lining body cavities.
Padding and lining

Question 15

Describe the function of muscle tissue?

Answer 15

Skeletal muscle under voluntary control attaches to bone for motion/posture, flexing and contracting.
Smooth muscle forming walls of tubes.
Cardiac muscle under involuntary control causing heart to pump.

Question 16

Describe the function of nervous tissue?

Answer 16

Neurones conduct electrical impulses throughout body to control body function/ movement/ secretion/ senses

Question 17

What are the six levels of organisation?

Answer 17

1) Chemical level
2) Cellular level
3) Tissue level- formed from groups of similar cells
4) Organ level- grouping 2 or more tissue type into recognisable structures with a specific function
5) System level- collection of related organs with a common function.
6) Organismal level- one living individual

Question 18

What is apoptosis?

Answer 18

Cell suicide

Question 19

What is necrosis?

Answer 19

Cell damage/ disease

Question 20

What happens to some cells?

Answer 20

Some are continually replaced, so cells are continually undergoing apoptosis.
Eg gut epithelium- turnover every 3 days
Some cells are never replaced, meaning they undergo apoptosis and never replaced
E.g muscle
Nervous system- 50% of cells die by the we’re old and is more rapid in neurodegenerative disorders

Question 21

Aging?

Answer 21

Mitosis slows down so cells that D die aren’t replaced, leading to the sign of aging
Apoptosis can increase in some cells causing disease e.g
alzhemer’s
Apoptosis can stop, causing cells to over-divide and form tumours

Question 22

What is homeostasis?

Answer 22

When conditions in the internal environment are maintained within physiological limits.
When it’s disturbed, illness may result. If body fluids and cells are not brought back into homeostasis, death may occur.

Question 23

What must be kept constant to protect the cell?

Answer 23

1) Chemical constitution- glucose, ions and ph
2) Osmotic pressure- water and soluble concentrations
3) Temperature- optimum
temperature for enzymes to work otherwise they will denature- stay at 37 degrees
4) 02 and CO2 levels

Question 24

How does homeostasis work?

Answer 24

1) Receptors- detect changes in the body
2) By having a control system- to initiate corrective measures.
Usually is a ‘nerve’ centre
3) Effectors- carry out effective measures

Question 25

Give a basic homeostatic control system?

Answer 25

1) Change in stimulus 2) Receptor 3) control centre 4) corrective response- negative feedback

Question 26

Control of high or low body temperature?

Answer 26

1) Receptor- skin & hypothalamus 2) Control centre hypothalamus & pituitary gland 3) Effector: Low to high- hair stands on end, vasoconstriction of capillary, skeletal muscles contract (shivering). High to low-sweating and vasodilation of capillaries

Question 27

Control of blood pressure?

Answer 27

1) Receptor- baroreceptors in artery walls 2)control centre-Medulla oblongata cardiovascular control centres in brain 3) Effector- heart and blood vessels 4) Corrective response- heart rate (inc for low BP and dec for high BP), blood vessels constrict (low BP) or dilate (high BP)

Question 28

Control of blood glucose?

Answer 28

1) Receptor- glucose receptors in the pancreas islet cells 2) control centre- islet cells 3) Effectors- insulin (dec blood sugar) or glucagon (inc blood sugar) 4) glucose uptake to cells or is converted into glycogen

Question 29

Control of blood volume- high blood volume

Answer 29

1) Receptor- arterial receptor in kidney 2) Control centre- brain, kidney 3) Effector- kidney function 4) Stop fluid intake, increase urine volume

Question 30

What is negative and positive feedback?

Answer 30

Negative Feedback: If response reverses original stimulus (tends to restore normal levels) Positive feedback: If response enhances original stimulus (continues to reinforce the original stimulus, often associated with the breakdown of systems)