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Biology > Topic 6 - Human health and physiology > Flashcards

Topic 6 - Human health and physiology Flashcards

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1
Q

Why is the digestion of large food molecules essential?

A

The molecules in food are too large to be transported across a cell membrane and need to be chopped into smaller molecules

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2
Q

Why are enzymes needed in digestion?

A

Enzymes lower the activation energy of chemical reactions increasing the rate of digestion and making it able for the reactions to occur at body temperature.

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3
Q

What kind of reactions do enzymes catalyse?

A

Hydrolysis reactions

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4
Q

How do enzymes (e.g. amylase) catalyse reactions?

A

Amylase temporarily holds the starch in its active site and puts stress on the covalent bonds that bind the monosaccharides together. When these bonds are stressed it is more likely for the thermal energy around to break the bonds.

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5
Q

State the source, substarte, products and optimum pH for amylase, protease, and lipase

A
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6
Q

Draw and label a diagram of the digestive system

A
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7
Q

Outline the function of the stomach

A
  • Food is held for a period of time to mix it with a variety of secretions known as gastric juice (pepsin, hydrochloric acid, mucus)
  • Muscular wall of the stomach creates a churning motion to intensify the mixing
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8
Q

Outline the function of the small intestine

A
  • Main function is to absorb nutrients
  • First part of the intestine is called duodenum, which secretes juices to continue the digestive process
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9
Q

Outline the function of the large intestine

A
  • Water absorption
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10
Q

Distinguish between absorption and assimilation

A

Absorption occurs when the food enters the body and the molecules pass through a layer of cells into the tissues (happens in small intestine). Assimilation occurs when the molecules become a part of the tissues of the body.

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11
Q

Explain how the structure of the villus is adapted to its role in absorption and transport

A
  • Microvilli on top of the villi increase the surface area used for absorption
  • Villi have an epithelium (one layer of cells), through which it is easier to diffuse
  • Protein channels in the microvilli allow rapid absorption by facilitated diffusion and pumps
  • Mitochondria in epithelium provide the ATP needed for active transport
  • Blood capillaries inside the villus are very close to the epithelium
  • A lacteal (branch of the lymphatic system) in the centre carries away fats
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12
Q

Draw and label the heart, showing the four chambers, associated blood vessels, valves, and the route of blood through the heart

A

This lacks the route of blood because I don’t know how to add two separate pictures

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13
Q

What do coronary arteries do?

A

They supply heart muscle with oxygen and nutrients

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14
Q

Outline the action of the heart in terms of collecting and pumping blood, and opening and closing of valves

A
  1. Blood flows from superior and inferior vena cavas to the right atrium and cannot proceed to the right ventricle because the atrioventricular valve prevents it
  2. The right atrioventricular valve is opened and blood flows to the right ventricle. The right semilunar valve is closed so blood cannot enter the lungs.
  3. The right ventricle contracts, closing the atrioventricular valve and opening the semilunar valve, sending the blood into the lungs through pulmonary artery to get oxygenated.
  4. The blood comes back from the lungs in the pulmonary veins and flow into the left atrium. The left atrioventricular valve is closed so the blood cannot enter the ventricle.
  5. The atrioventricular valve opens and allows flow to the left ventricle. Left semilunar valve is closed.
  6. The ventricle contracts, closing the atrioventricular valve and opening the semilunar valve. Blood enters the aorta and into the whole body.
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15
Q

What kind of muscle is the heart made of and how is it special?

A

It is made of cardiac muscle which can spontaneously contract and relax without nervous system control. (also known as myogenic muscle contraction)

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16
Q

Where is the pacemaker located?

A

On the tissue of the right atrium

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17
Q

Outline the stages of one heart beat

A
  1. The sinoatrial node (SA node) sends a signal to initiate the contraction of both atria. Both atria contract.
  2. The atrioventricular node (AV node) receives the signal from the SA node and waits for approximately 0.1 seconds. After this is sends a signal to both of the ventricles, which then contract.

This is why both atria and a bit later both ventricles contract together.

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18
Q

Outline the stages of increasing heart rate during and decreasing after excercise

A
  1. Medulla in the brainstem chemically detects the increased CO2 level in the blood.
  2. The medulla then sends a signal through a cranial nerve, the cardiac nerve, to increase the heart rate to an appropriate level. This signal is sent to the SA node.
  3. After exercise the medulla again detects the decrease in the level of CO2.
  4. The medulla then sends a signal through another cranial nerve, the vagus nerve, to lower the herat rate. This signal is again sent to the SA node.
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19
Q

Outline how chemicals (adrenaline) can affect the heart rate

A

During periods of stress or excitement, adrenal glands secrete adrenaline (epinephrine) into the bloodstream. The adrenaline causes the SA node to send signals more frequently than usually.

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20
Q

Compare arteries, capillaries, and veins

A
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21
Q

Describe the structure of arteries

A
  • They have a thick smooth muscle layer to regulate and withstand the high blood pressure
  • No internal valves
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22
Q

Describe the structure of veins

A
  • Thin muscle walls because low blood pressure
  • Large internal diameter → more blood fits in
  • Slow blood flow
  • Many internal valves to prevent back-flow of blood
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23
Q

Describe capillaries

A
  • The wall is only one cell thick to enable diffusion of oxygen
  • Many have a diameter equal to a blood cell
  • No internal valves
  • Low pressure
  • All exchanges occur in capillaries
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24
Q

What is blood composed of?

A
  1. Plasma
  2. Erythrocytes
  3. Leucocytes (phagocytes and lymphocytes)
  4. Platelets
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25
Q

Describe the role of each component of blood

A
  1. Plasma: the liquid portion of blood
  2. Erythrocytes: red blood cells (carry oxygen and CO2)
  3. Leucocytes: white blood cells
  4. Platelets: cell fragments that assist in blood clotting
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26
Q

What substances are transported by the blood?

A
  1. Nutrients
  2. Oxygen
  3. Carbon dioxide
  4. Hormones
  5. Antibodies
  6. Urea
  7. Heat
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27
Q

Give examples of each substance transported by blood

A
  1. Nutrients: glucose, amino acids, etc.
  2. Oxygen: needed for aerobic cell respiration
  3. Carbon dioxide: waste product of aerobic cell respiration
  4. Hormones: transported from glands to target cells
  5. Antibodies: protein molecules involved in immunity
  6. Urea: nitrogenous waste (filtered by kidneys)
  7. Heat: well, heat
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28
Q

Define pathogen

A

An organism or virus that causes disease

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29
Q

Why are antibiotics effective against bacteria but not viruses?

A

Antibiotics block specific metabolic pathways found in bacteria. Viruses do not have metabolism per se, thus are not affected by antibiotics.

30
Q

Outline the role of skin in defence against pathogens

A

Skin acts as a physical barrier between the body and pathogens. The upper layer, epidermis, is composed of dead skin cells, that are not affected by pathogens and prevent their entry to the rest of the body. As long as the skin remains intact, the body is safe from most pathogens.

31
Q

Outline the role of mucous membranes in defence against pathogens

A

The cells of mucous membranes secrete a lining of sticky mucus, which can make the pathogens stick to it, preventing them from reaching cells they could infect. Some membranes are lined with cilia, hair-like extensions that can move the trapped pathogens up and out of the crucial areas. The mucous cells also secrete lysozyme, which can damage pathogens.

32
Q

Describe how phagocytic leucocytes ingest pathogens

A

Large white blood cells called macrohpages are able to change their cellular shape to surround an invader and ingest it. The cell recognises another cell according to the protein molecules on the surface of the cell and labels it either ‘self’ or ‘not-self’. In case of ‘not-self’ identification, the macrophage engulfs the cell and initiate phagocytosis.

33
Q

Explain how macrophages are able to exit blood vessels to attack phagocytes

A

Since they are able to change their cellular shape, they can squeeze through the walls of small blood vessels.

34
Q

Distinguish between antigens and antibodies

A

Antibodies are protein molecules that the body produces in response to a specific type of pathogen.

Antigens are proteins embedded into the outer surface of antibodies and are used by phagocytes to detect the cell as ‘not-self’.

35
Q

Briefly explain antibody production

A

Many different types of lymphocytes exist. Each type recognises one specific antigen and respons by dividing to form a clone. This clone then secretes a specific antibody against the antigen.

36
Q

Outline the effects of HIV on the immune system

A
  • A reduction in the number of active lymphocytes
  • Loss of the ability to produce antibodies
  • Eventually loss of immune system
37
Q

Explain the cause of AIDS

A
  • Caused by HIV that has developed into AIDS
  • HIV infects cells called helper-T cells
  • These helper-T cells are the ones that communicate which cells need to undergo the cloning process and begin antibody production
  • When helper-T cells die, the communication between cells dies too → antibodies are no longer produced
  • The body cannot fight against pathogens and dies
38
Q

List the ways HIV is transmitted

A

Essentially by body fluids:

  1. Body fluid exchanges during sex
  2. Reusing unsterile syringe needles in drug injections
  3. Untested blood transfusions
39
Q

Discuss the social implications of AIDS

A
  • Patients may be discriminated in terms of employment, insurance, education access, and social acceptance
  • Not every country has the education and medical facilities to deal with AIDS
  • Sometimes patiens are grouped together which leads to an exchange of diseases between them
  • Family and friends suffer grief
40
Q

Distinguish between ventilation, gas exchange, and cell respiration

A

Ventilation = filling and unfilling the lungs with air

Gas exchange = diffusion of gases in the lungs and capillaries

Cell respiration = the process that requires gas exchange (oxygen ⇔ carbon dioxide)

41
Q

Why is a ventilation system needed?

A
  1. The human body is too thick for gases to diffuse in and out → an alternative route is required
  2. Maintaining high concentration gradients in the alveoli to ensure that gases continue on diffusing
42
Q

Describe the features of alveoli that adapt them to efficient gas exchange

A
  1. Spherical shape provides a large total surface area for gases to diffuse through
  2. A wall made of a layer of single flattened cells makes it easier for the gases to diffuse
  3. Moist inner lining of alveoli allow efficient diffusion
  4. A dense network of capillaries attached to the alveoli so that the gases do not have to travel far by themselves
43
Q

Draw and label a diagram of the ventilation system

A
44
Q

Describe the stages in the mechanism of ventilation

A

Inspiration

  1. The abdominal muscles and intercostal muscles contract to raise the rib cage. The diaphragm contracts downwards to increase the volume of the thoraric cavity.
  2. The pressure inside the cavity increases, causing the lungs to increase in volume.
  3. The pressure inside the lungs also decreases creating a partial vacuum.
  4. Air comes in through mouth and nose to fill the partial vacuum inside the lungs.

Expiration is the same steps in reverse order

45
Q

What does the nervous system consist of?

A
  1. The central nervous system (CNS)
  2. Peripheral nerves
  3. Neurons
46
Q

Draw and label a diagram of the structure of a motor neuron

A
47
Q

What is the route of a nerve impulse to the CNS, within the CNS, and from the CNS

A
  1. To the CNS by sensory neurons
  2. Within the CNS by relay neurons
  3. From the CNS to effectors by motor neurons
48
Q

What is the role of myelin sheaths?

A

To increase rate at which an action potential passes down an axon

49
Q

Describe a neuron in resting potential

A
  • Ready to send an action potential (but is not currently sending)
  • Is said to be polarised
  • Active transport of Na+ and K+ is occurring in two different directions
  • Na is transported out of the axon cell and K is transported into the cytoplasm
  • There is a net positive charge outside the axon and a net negative charge inside the axon
50
Q

Describe a neuron in action potential (depolarisation)

A
  • Wave-like movement across the axon
  • Na and K channels open causing Na ions to diffuse in and K ions to diffuse out
  • This area initiates the depolarisation of the next area → goes on until the end of the axon is reached

-

51
Q

How does a neuron return to its resting potential (repolarisation)?

A

Active transport is used to pump Na and K ions out and in, respectively, to gain resting potential.

52
Q

Define refractory period of a neuron

A

The time it takes for one neuron to send an action potential and then repolarise so it can send another one.

53
Q

Distinguish between presynaptic and postsynaptic neuron

A

Presynaptic neuron carries the action potential to the end of its axon and connects the postsynaptic neuron’s dendrites, from which the action potential continues its path

54
Q

Define neurotransmitter

A

Any chemical that is used for synaptic transmission (e.g. acetylcholine)

55
Q

Outline the steps in synaptic transmission

A
  1. Action potential reaches the terminal button
  2. Calcium ions (Ca2+) diffuse into the terminal buttons
  3. Vesicles containing neurotransmitter fuse in and release the transmitter
  4. Neurotransmitter diffuses across the synaptic cleft from the presynaptic to the postsynaptic neuron
  5. Transmitter binds with a receptor protein on the postsynaptic neuron membrane
  6. This binding results in the opening of an ion channel and Na ions diffusing into the cell
  7. This initiates action potential in the postsynaptic neuron
  8. Neurotransmitter is broken down and released from the receptor protein
  9. The ion channel closes (repolarisation)
  10. Neurotransmitter fragment diffuse back across the synaptic cleft to be reassembled in the terminal button of the presynaptic neuron
56
Q

What does the endocrine system consist of?

A

Glands that release hormones that are transported in the blood

57
Q

What is the role of homeostasis?

A

To maintain the internal environment between limits, including:

  • blood pH
  • CO2 concentration
  • blood glucose concentration
  • body temperature
  • water balance
58
Q

What does homeostasis do?

A

It monitors levels of variables and corrects changes in levels by negative feedback mechanisms

59
Q

Explain the control of body temperature

A

Increased body temperature:

  • Hypothalamus receives information from thermoreceptors in skin → initiates cooling mechanisms
  • Increased activity of sweat glands → evaporation of water has a cooling effect
  • Skin arterioles dilate and heat radiates more easily out

Decreased body temperature:

  • Hypothalamus
  • Skin arterioles are constricted and blood is diverted into deeper organs and tissues → less heat is lost by radiation
  • Skeletal muscles are stimulated to shiver → constant movement generates body heat
60
Q

Explain the control of blood glucose concentration

A

Hepatocytes (liver cells) act on blood and either increase or decrease the glucose level according to hormones (insulin and glucagon)

Increased glucose level:

  • Beta cells produce insulin
  • Insulin affects on body cells and open protein channels in plasma membranes and glucose diffuses into the cell by facilitated diffusion
  • Insulin also stimulates hepatocytes to take in glucose and convert it into glycogen and store it in granules

Decreased glucose level:

  • Alpha cells produce glucagon
  • Glucagon stimulates hydrolysis of glycogen stored in granules
  • Glycogen is hydrolysed into glucose and glucose enters the bloodstream
61
Q

Distinguish between type I and type II diabetes

A

Type I

  • An autoimmune disease, the immune system attacks and destroys beta cells → no insulin is produced
  • Rare and most often develops in young people

Type II

  • Body develops insulin resistance
  • Due to genetic history, obesity, lack of exercise, advanced age, and certain ethnic groups
  • Most common
62
Q

Draw and label a diagram of the adult male reproductive system

A
63
Q

Draw and label a diagram of the adult female reproductive system

A
64
Q

What is the role of follicle stimulating hormone (FSH)?

A
  • Starts the menstrual cycle
  • Stimulates the follicle to grow and develop an egg cell
  • Stimulates estrogen secretion by the follicle cells
65
Q

What is the role of luteinizing hormone (LH)?

A
  • Causes the egg to be released from the follicle (ovulation)
  • Causes the follicle to develop into a corpus luteum
66
Q

What is the role of estrogen?

A
  • Make the follicle cells produce more FSH receptors and respond more strongly to FSH
  • Stimulate the repair of the uterus lining (endometrium)
  • (levels peak and) stimulate LH secretion by the pituitary gland
67
Q

What is the role of progesterone?

A
  • After ovulation
  • Causes the uterus lining to prepare for an embryo
  • Inhibit FSH and LH secretion after ovulation
68
Q

Annotate a graph showing hormone levels in the menstrual cycle, illustrating the relationship between the changes in hormone levels and ovulation, menstruation and thickening of the endometrium

A
69
Q

List three roles of testosterone in males

A
  1. Pre-natal development of male genitalia
  2. Development of secondary sexual characteristics
  3. Maintaining sex drive
70
Q

Outline the steps of in vitro fertilisation (IVF)

A
  1. A drug is used for three weeks to stop the woman’s menstrual cycle
  2. Large doses of FSH are injected for 10 days to stimulate the growth of many follicles
  3. Several eggs are harvested surgically
  4. The man provides semen by ejaculating into a container
  5. Eggs are mixed with sperm
  6. The dishes are checked if fertilisation has occurred
  7. Two or three embryos are implanted into the uterus
71
Q

What are arguments for IVF?

A
  1. Enables infertile couples to have children
  2. Unhealthy embryos can be eliminated at an early stage
  3. Genetic screening is possible before implantation to eliminate genetic diseases
  4. Embryos killed during the process are unable to feel pain or suffer
72
Q

What are arguments against IVF?

A
  1. Excess embryos are destroyed
  2. Genetic screening may lead to choosing desirable characteristics
  3. Some forms of infertility are passed on in genes
  4. Infertility should be accepted as the will of God

Biology (13 decks)

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