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Human physiology Flashcards

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AP® Biology flashcards Biology 101 flashcards
0
Q

Explain the need for enzymes in digestion

A

Without enzymes digestion would still occur, however at a significantly slower pace.

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1
Q

Explain why digestion of large food molecules is essential (2)

A
  • The foods that we eat are not necessarily usable in their current form by our tissues. They have to be broken down and rearranged to “human versions”.
  • original ingested molecules are often too large to be absorbed by the villi in the small intenstine so they must be broken down to be absorbed.
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2
Q

Outline the function of the stomach

A

Digestion of proteins begins in the stomach, where the process is sped up by the enzyme pepsin. Harmful bacteria that has entered the body can be killed by the stomach’s acidic environment(pH 1.5-2).

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3
Q

Outline the function of small intestine

A

In the small intestine, enzymes complete the process where the end matter is absorbed by villi.

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4
Q

Outline the function of large intestine

A

The large intestine absorbs water and passes the unabsorbable rest off as feces.

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5
Q

Absorption

A

Absorption is when food molecules pass through a layer of cells such as passing through the villi.

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6
Q

Assimilation

A

Assimilation is when food actually becomes part of the body’s tissue.

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7
Q

Explain how the structure of the villus is related to its role in absorption of the end products of digestion

A
  • It increases the surface area of the small intestine
  • The epithelium has a surface of only a thin layer of cells.
  • Protein channels in the microvilli allow for quick absorption of foods via facilitated diffusion and active transport.
  • Blood capillaries close to epithelium making it only a small distance for diffusion to occur.
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8
Q

Outline the control of the heartbeat in terms of the pacemaker, nerves, and adrenalin.

A

The pacemaker is located in the wall of the right atrium at the Sinoatrial node (SAN). Each time the pacemaker sends out a signal, the heart carries out a contraction or a beat. The heart beats by itself (myogenic). Nerves and hormones can transmit messages to the pacemaker: Sympathetic nerve secretes adrenaline (also known as “epinephrine”) which carries messages from the brain to the pacemaker telling the pacemaker to speed up the beating of the heart. Another nerve tells it to slow it down.

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9
Q

Characteristics of arteries (5)

A

1) Thick wall to withstand high blood pressure.
2) Thick outer layer of longitudinal collagen and elastic fibers.
3) Thick layers of circular elastic and muscle fibers.
4) walls stretch and recoil for the blood to go from the heart to the small intestine.
5) Narrow lumen to help maintain the high pressure..

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10
Q

Characteristics of veins (5)

A

1) Thin layers with a few circular elastic and muscle fibers.
2) Thin walls to allow the muscles to squeeze the veins
3) Thin outer layer of longitudinal collagen and elastic fibers.
4) Valves for blood to stay and not flow backwards.
5) Wide lumen to accommodate for the slow flowing of blood

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11
Q

Characteristics of capillaries

A

Wall - single layer of thin cells, so the distance for diffusion is small
Very narrow lumen (only 10 um) so that capillaries fit into small spaces
Pores between cells in the wall allow some of the plasma to leak out and form tissue fluid; phagocytes can also squeeze out

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12
Q

Composition of blood

A

Plasma
Erythrocytes
Leukocytes
Platelets

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13
Q

Functions of blood (2)

A

1) defense against infectious disease (Leukocytes)
2) transport of
- oxygen (red blood cells)
- nutrients, CO2, hormones, antibodies, urea (plasma)
- heat (from the core to skin)

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14
Q

Pathogen

A

An organism or virus that causes a disease

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15
Q

Antibiotics

A

Chemicals produced by microorganisms to kill or control the growth of other microorganisms
e.g. Penicillium fungus produces penicillin to kill bacteria

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16
Q

Why viruses can’t be treated with antibiotics?

A

Viruses carry out ver few life processes themselves; instead they rely on a host cell to carry out processes for them - it’s impossible to block their function without damaging the host

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17
Q

Barriers to infection (2)

A

Skin

Mucous membranes

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18
Q

Skin as a barrier to infection

A

Physical barrier - outer layers are tough
Chemical barrier - sebaceous glands in the skin secrete lactic acid and fatty acid, which make the skin surface acidic, preventing growth of most pathogenic bacteria

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19
Q

Mucous membranes as a barrier to infection

A

Don’t form a strong physical barrier, but have the enzyme lysozyme which kills most bacteria
In nose, pathogens get caught in the sticky mucous and then are pushed out thanks to cilia
Membranes in: nose, trachea, vagina, urethra

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20
Q

Phagocytes

A

Can identify pathogens and ingest them by endocytosis
Can ingest them in blood or squeeze through the walls of blood capillaries and move through tissues to the site of infection
Ingested pathogens are usually killed and digested inside a phagocyte

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21
Q

Antigen

A

Foreign substance that stimulates production of antibodies,

E.g. cell walls of pathogenic bacteria or fungi

22
Q

Antibody

A

Protein,
Recognizes specific antigens and defends the body by binding to antigens on the surface of a pathogen and stimulating its destruction
Usually binds to only one specific antigen

23
Q

Antibody production

A

Antibodies are made by B lymphocytes
Pathogen enters -> its antigens bind to antibodies in the plasma membrane of 1 type of lymphocyte -> this lymphocyte becomes active -> divides by mitosis to produce a clone of many identical cells -> the clone produces large amounts of the same antibody! needed to defend organism against the pathogen

24
Q

AIDS

A

Acquired immunodeficiency syndrome
Symptoms: low numbers of one type of lymphocytes, quick weight loss, vulnerability to a variety of diseases cause by bacteria, viruses, fungi, and protoza - body is weak, dies eventually

25
Q

HIV

A

Human Immunodeficiency Virus
Causes AIDS
Infects a type of lymphocyte that plays a vital role in antibody production (B lymphocytes)
Over years, these lymphocytes are destroyed and antibodies cannot be produced

26
Q

Ventilation

A

The flow of air in and out of the alveoli to bring fresh air and remove the stale one
Maintains concentration gradients of oxygen and carbon dioxide between the air and the blood

27
Q

Gas exchange

A

Diffusion of gases (oxygen and co2)
In the alveoli of human lungs
- oxygen diffuses from air in alveoli to blood in capillaries
- CO2 diffuses from capillaries to alveoli

28
Q

Cell respiration

A

In the cytoplasm and mitochondria of cells
Releases energy in the form of ATP for use inside the cell
- aerobic respiration uses oxygen and produces CO2
- anaerobic respiration doesn’t use oxygen yet still produces CO2

29
Q

Nervous system

A

Central nervous system (brain + spinal cord)
Peripheral nervous system (all nerves except the CNS)
Composed of elongated cells called neurons

30
Q

Neurons

A

Carry electrical impulses over long distances in the body
Basic functional unit of the nervous system
Sensory neurons - from receptors to CNS
Motor neurons - from CNS to effectors
Relay neurons - within the CNS, from one neuron to another

31
Q

Parts of a motor neuron (8)

A 
Cell body
Nucleus
Dendrites
Axon
Myelin sheet
Nodes of Ranvier
Motor end plates (attached to skeletal muscle fibers)
32
Q

Resting potential

A

Electrical potential across the plasma membrane of a cell that isn’t conducting an impulse
(+|- -|+)

33
Q

Action potential

A

Reversal and restoration of the electrical potential across the plasma membrane of a cell as a electrical impulse passes along it
(Depolarization + repolarization)

34
Q

Passage of a nerve impulse

A

1) resting potential - no impulse
2) depolarization - sodium channels open - Na+ diffuses NAjpierw into; potential across the membrane is reversed
3) repolarization - sodium channels open - K+ diffuses out - potential is restored
4) active transport - sodium potassium pumps - concentration gradients are restored

35
Q

Homeostasis

A

Maintaining the internal environment of the body between limits
Controlled parameters: body temperature, carbon dioxide concentration, blood glucose concentration, water balance
Controlled by both nervous and endocrine systems
Involves monitoring levels of variables and correcting any deviations by NEGATIVE FEEDBACK mechanisms

36
Q

Negative feedback

A

Has a stabilizing effect - a change in levels always causes the opposite change (increase in levels - decrease of production; decrease in levels - increase in production)

37
Q

Functions of hypothalamus of the brain (3)

A

1) monitors the temperature of the blood
2) compares blood temperature with a set point (around 37°C)
3) sends messages to parts of the body to make them responds if temperature varies from a set point (negative feedback)

38
Q

Responses to overheating (3)

A

1) skin arteriolar become wider - more blood flows through the skin (this blood transfers heat from the core to the skin -> temperature of the skin rises -> more heat is lost from skin to the environment)
2) skeletal muscles relaxed and resting (don’t generate heat)
3) sweat glands secrete large amounts of sweat, making the skin damp -> water evaporates! has cooling effect

39
Q

Responses to chilling

A

1) skin arterioles become narrower - bring less blood to the skin, so less heat is lost to the environment
2) skeletal muscles do many rapid contractions - shivering
3) sweat glands don’t secret sweat - dry skin, no cooling

40
Q

Control of blood glucose concentration

A
  • monitored by cells in the pancreas which send hormone messages to target organs when the level is too high / low (negative feedback)
  • blood glucose cannot be kept as steady as body temperature
  • concentration usually between 4 and 8 millimoles per dm3 of blood
41
Q

Responses to high blood glucose levels

A
  • ß cells in the pancreatic islets produce insulin
  • insulin stimulates the LIVER and MUSCLE CELLS to absorb glucose from the blood and convert it to glycogen (which is then stored in the cytoplasm of these cells)
  • other cells stimulated to absorb glucose and use it in cell respiration instead of fat
42
Q

Responses to low blood glucose levels

A
  • a (alpha) cells in the pancreatic islets produce GLUCAGON

- glucagon stimulates liver cells to break glycogen down into glucose and release it into blood

43
Q

Type I diabetes

A

Onset: early childhood
Reason: ß cells produce insufficient insulin
Treatment: insulin injections to control blood glucose level

44
Q

Type II Diabetes

A

Onset: after childhood
Reason: target cells become insensitive to insulin (cannot respond to hormone messages sent by cells in the pancreas)
Treatment: insulin injections usually not needed; a diet low in carbs usually controls the condition

45
Q

Diabetes (general)

A 
Full name: Diabetes mellitus
When the mechanisms controlling blood glucose do not work effectively
Social effect: personal suffering
side effect: kidney failure
Economic effect: high costs of treatment
46
Q

FSH

A

Follicle Stimulating Hormone
Secreted by: pituitary gland
Stimulates development of follicles
Peaks first

47
Q

Follicles

A

Fluid-filled sacs which contain an egg cell

48
Q

LH

A

Luteinising Hormone
Secreted by: pituitary gland
Stimulates follicles to become mature, release their eggs (ovulation) and then develop into corpus luteum
Peaks at ovulation

49
Q

Estrogen

A

Secreted by the ovary
Stimulates development of endometrium
Inhibits secretion of FSH, preventing further stimulation of development of more follicles (negative feedback)

50
Q

Progesterone

A

Secreted by: the ovary
Continues the build up of endometrium
Inhibits secretion of FSH and LH

51
Q

Estrogen & progesterone

A

Both stimulate development of female secondary sexual characteristics

  • maturation of ovaries
  • vagina enlargement
  • breasts
  • pubic hair
  • fat deposition under the skin of buttocks and thights
  • menstruation
52
Q

Testosterone

A

Produced by: cells of testes

  • pre natal development of male genitalia
  • male secondary characteristics during puberty (enlarged penis, scrotum, tested, and glands; pubic hair; growth of skeletal muscles; sex drive)
  • maintains high levels of sex drive, stimulates sperm production by testes

Biology (9 decks)

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