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IB Biology 22-24 > Topic 6: Human Physiology > Flashcards

Topic 6: Human Physiology Flashcards

1
Q

Explain how circulation of the blood to the lungs and to other systems is separated in humans and what the advantages of this separation are. [8]

A
  • double circulation
  • heart is a double pump
  • deoxygenated blood pumped into lungs, oxygenated blood pumped to other organs
  • each side of the heart has an atrium and ventricle
  • left ventricle pumps blood to the systems; right ventricle pumps blood to the lungs
  • left atrium receives blood from the lungs; right atrium receives blood from systems
  • left ventricle pumps blood via the aorta; right ventricle pumps blood via the pulmonary artery
  • left atrium receives blood via the pulmonary vein; right atrium receives blood via the vena cava
  • lungs require low pressure blood
  • high pressure to pump blood
  • oxygenated and deoxygenated blood kept separate
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2
Q

Describe the action of the heart in pumping blood. [5]

A
  • atria collects blood from veins
  • sinoatrial node sends impulses to muscle
  • blood is pushed to ventricles by contraction of atria
  • atrioventricular valves open
  • semilunar valves are closed so ventricles fill with blood
  • when ventricles relax, semilunar valves close to prevent backflow of blood
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3
Q

Distinguish between the composition of the blood of the renal artery and the blood of the renal vein.

A

Renal Vein

  • less urea
  • less oxygen
  • more CO2
  • less glucose
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4
Q

State four molecules transported by the blood.

A
  • hormones
  • antibodies
  • urea
  • O2
  • CO2
  • glucose
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5
Q

Outline control of the heartbeat [4]

A
  • myogenic
  • SA node
  • stimulates atria to contract
  • leading to contraction of ventricles
  • nerves carry impulses from the brain to alter pace
  • medulla monitors blood pressure
  • secretion of adrenaline increases pace
  • secretion of acetylcholine reduces pace
  • adrenal gland release adrenaline
  • carried by blood to heart to increase pace
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6
Q

Outline exchange of materials between capillaries and tissues [3]

A
  • molecules move by diffusion down a conc gradient
  • nutrients move into tissues
  • gas exchange
  • nitrogenous wastes move from cell tissues to blood
  • hormones leave capillaries to target tissues/gland tissues release hormones into bloodstream
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7
Q

Explain the structures and functions of arteries and veins. [8]

A
  • three layers in their wall
  • pressure high in arteries, low in veins
  • arteries carry blood away from heart
  • lumen of artery is small to maintain high pressure
  • arteries have thick walls to withstand pressure
  • elastic fibres recoil in response to heart contractions
  • veins receive blood from capillaries
  • large lumen of veins, less resistance to blood flow
  • valves in veins prevent backflow of blood
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8
Q

Explain how the small intestine moves, digests and absorbs food. [8]

A
  • contraction/peristalsis moves food
  • peristalsis mixes food with intestinal enzymes
  • enzymes digest macromolecules into monomers
  • amylase digests starch/lipase digests lipids
  • bile secreted into small intestine creates favorable pH for enzymes
  • bile emulsifies fat
  • lining of small intestine with villi
  • villi increases SA for better absorption
  • villi absorbs products of digestion
  • glucose enters blood via capillaries
  • absorption involves active transport/diffusion
  • different nutrients absorbed by different transport mechanisms
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9
Q

State the source, substrate, products and optimal pH condition for lipase in the human digestive system. [4]

A
  • source: pancreas
  • substrate: lipids
  • product: glycerol and fatty acids
  • optimal pH: 7-8
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10
Q

Describe the process of blood clotting. [4]

A
  • clotting factor released by platelets
  • series of reactions
  • prothrombin activated to thrombin
  • soluble fibrinogen to insoluble fibrin
  • mesh of fibrin traps red blood cells
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11
Q

Explain how the direction of blood flow in the heart is controlled. [2]

A
  • valves open/close due to pressure differences
  • valves prevent backflow
  • atrioventricular valves between ventricles and atria
  • semilunar valves between arteries and ventricles
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12
Q

Blood transports molecules throughout the body. State where the blood absorbs hormones.

A

endocrine glands

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13
Q

Blood transports molecules throughout the body. State where the blood absorbs carbon dioxide.

A

tissues

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14
Q

Explain how the structure of capillaries relates to their functions. [3]

A
  • one cell thick for better diffusion
  • narrow lumen to fit in between cells
  • small diameter for greater SA for molecular exchange
  • pores between cells of the wall so plasma can leak out
  • allows phagocytes to enter tissues
  • only one red blood cell passes at a time for efficient oxygen uptake
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15
Q

The pumping of blood is a vital process. Explain the roles of the atria and ventricles in the pumping of blood. [4]

A
  • atria collects blood from veins
  • collects blood while ventricles contract
  • atria pumps blood into ventricles
  • ventricles pump blood into arteries
  • at high pressure
  • heart valves work with atria and ventricles to keep blood moving
  • left ventricle pumps blood to systems; right ventricle pumps blood to lungs
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16
Q

Explain how the structure of an artery allows it to carry out its function efficiently. [5]

A
  • thick wall to withstand high pressure
  • many muscle fibres to pump blood
  • many elastic fibres to stretch and pump blood after each heart beat
  • narrow lumen to maintain high pressure
  • thick outer layer of collagen to give strength
  • no valves, pressure is high enough to prevent backflow
  • smooth inner lining to prevent friction
17
Q

Define endocytosis.

A

small droplets of the fluid are passed through the membrane by means of vesicles

18
Q

Describe the cardiac cycle.

A
  1. Walls of atria contract, pushing blood from atria into ventricles through opened atrioventricular valves. Semilunar valves are closed to fill ventricles with blood
  2. Walls of ventricles contract, raising blood pressure. Atrioventricular valves close to prevent backflow, and semilunar valves open to pump blood into arteries
  3. Ventricles stop contracting, pressure falls. Semilunar valves close, preventing backflow
  4. Cycle repeats when walls of atria contract again
19
Q

Explain how circulation of the blood to the lungs and to other systems is separated in humans and what the advantages of this separation are. [8]

A
  • double circulation
  • left and right sides of the heart are separated (double pump)
  • deoxygenated blood pumped to lungs, oxygenated blood pumped to the rest of the body
  • each side of the heart has an atrium and a ventricle
  • left ventricle pumps blood to tissues, right ventricle pumps blood to the lungs
  • left atrium receives blood from the lungs, right atrium receives blood from tissues
  • left ventricle pumps blood via aorta, right ventricle via pulmonary artery
  • left atrium receives blood via pulmonary vein, right atrium receives blood via vena cava
  • lungs require lower pressure blood
  • high pressure required to pump blood to all systems
  • oxygenated blood and deoxygenated blood are kept separate
20
Q

Outline the role of the skin in temperature regulation. [5]

A
  • heat causes vasodilation of arterioles
  • blood closer to surface, so heat loss from skin
  • heat causes sweating
  • evaporation of sweat leads to cooling
  • cold causes vasoconstriction of arterioles
  • less blood at surface, less heat loss
  • cold leads to less sweating
  • temperature receptors in skin transmit impulses to hypothalamus
21
Q

Describe how body temperature is maintained in humans. [6]

A
  • maintained close to 37°C
  • heat distributed in body by blood
  • hypothalamus contains thermoreceptors
  • hypothalamus monitors temperature
  • vasodilation of arterioles cools skin
  • vasoconstriction of arterioles retains body heat
  • sweat glands produce sweat to cool body
  • removal of heat through evaporation of sweat
  • shivering generates heat
22
Q

Distinguish between ventilation, gas exchange and cell respiration. [4]

A
  • ventilation is inhalation and exhalation
  • involves respiratory muscle activity
  • gas exchange involves movement of CO2 and O2
  • between blood and cells
  • cell respiration is the release of energy from glucose
  • occurs in mitochondria
23
Q

Outline the control of the heartbeat by the nervous and endocrine systems. [6]

A
  • myogenic muscle contraction
  • contracts without stimulation
  • SA in right atrium wall
  • SA initiates contraction
  • nerves from brain transmit messages to pacemaker
  • to alter pacemaker rate
  • medulla of brain controls heart rate
  • adrenaline produced by adrenal gland
  • adrenaline accelerates heart rate
24
Q

Explain the principles of synaptic transmission. [8]

A
  • calcium ions enter presynaptic neuron
  • releases neurotransmitter
  • from presynaptic membrane
  • diffusion across cleft
  • to postsynaptic membrane
  • binding of neurotransmitter to receptors
  • change in membrane permeability
  • sodium ions flow into postsynaptic neuron
  • depolarizes postsynaptic membrane
  • intiates action potential
  • removes neurotransmitter
  • by acetylcholinesterase
  • inactivated neurotransmitter returns to presynaptic neuron
25
Q

Explain the concept of homeostasis, using the control of blood sugar as an example. [9]

A
  • maintaining a constant internal environment within narrow limits
  • e.g. body temperature
  • negative feedback
  • variation from normal levels trigger correction mechanisms
  • controlled by nervous/endocrine (hormonal) systems
  • blood sugar above normal stimulates insulin release
  • insulin secreted by beta cells in islets of pancreas
  • lowers blood sugar
  • by converting glucose to glycogen
  • blood sugar below normal stimulates glucagon release
  • glucagon secreted by alpha cells in islets of pancreas
  • glycogen converted to glucose
26
Q

Explain how nerve impulses are transmitted along and between neurons. [9]

A
  • resting potential of the cell is negative inside
  • stimulation causes depolarization
  • Na+ flows into the cell
  • causes action potential
  • K+ flows out of the cell
  • sodium-potassium pump restores resting potential
  • transmitted between neurons across a synapse
  • neurotransmitter released into synaptic cleft
  • diffuse across cleft to postsynaptic membrane
  • binds to receptors
27
Q

Explain the propagation of electrical impulses along a neuron including the role of myelin. [8]

A
  • neurotransmitter attaches to receptors, initiates transmission
  • nerve impulses are action potentials propagated along the axons of neurons
  • resting potential more negative inside (-70mV)
  • channels open and Na+ diffuses in
  • depolarizes the membrane (-70mV to +40mV)
  • causes an action potential
  • followed by repolarization
  • channels open and K+ diffuse out
  • Na-K pumps restore resting potential
  • myelin insulates the axon
  • to permit saltatory conduction (speeds up transmission)
28
Q

Describe what happens in alveoli. [4]

A
  • gas exchange
  • oxygen diffuses from air to blood and carbon dioxide diffuses from blood to air
  • oxygen binds to haemoglobin in RBC
  • air enters alveoli during inspiration
  • blood flow through capillaries maintains a concentration gradient
  • type II pneumocytes secrete surfactant
29
Q

Describe the production of hybridoma cells, giving an example. [3]

A
  • antigen injected into host
  • B cells extracted
  • fusion of plasma cells with tumour cell
  • division of hybridoma cells to form clones
  • produce monoclonal antibodies
  • pregnancy testing
  • treatment of rabies
30
Q

Actin and myosin are two proteins found in muscles. Explain how skeletal muscle contracts, including the interaction of these proteins. [8]

A
  • motor neuron stimulates muscle fiber
  • calcium ions released from the sarcoplasmic reticulum
  • calcium ions bind to troponin
  • tropomyosin moved
  • ATP binds to myosin, causing cross-bridges to break
  • ATP is hydrolyzed to ADP + Pi causing myosin heads to change the angle
  • myosin heads attach to new actin sites
  • ADP releases
  • myosin heads move actin filament to centre
  • sarcomere is shortened
  • calcium ions reabsorbed by sarcoplasmic reticulum
  • muscle fibre relaxes
31
Q

Compare and contrast hormonal and nervous communication. [7]

A

Similarities

  • communication between cells
  • causes response in target cells
  • stimulate or inhibit processes
  • work over long distances
  • under control of CNS
  • used in homeostasis

Hormonal

  • chemical messenger
  • through bloodstream
  • slower
  • all tissues affected
  • long term

Nervous

  • electrical messenger
  • through neurons
  • faster
  • only muscles/glands
  • short-lived
32
Q

Outline how carbon dioxide carried to the lungs in the pulmonary artery is moved to the air outside the body. [7]

A
  • CO2 excreted by alveoli
  • network of capillaries surrounds alveolus wall
  • diffusion of CO2
  • CO2 from blood to alveolus
  • thin capillary walls allow short diffusion distance
  • higher conc. of CO2 in blood
  • air from alveolus passes out of body
  • air forced out by ventilation
  • due to lungs increasing in pressure/decreasing in volume
  • air flows from high to low pressure
  • when the diaphragm relaxes
  • contraction of muscles in the internal intercostal muscles
  • air containing CO2 flows out through bronchioles
33
Q

Explain how the kidney produces urine with a higher conc. of urea than blood plasma. [5]

A
  • ultrafiltration/urea filtered out of blood plasma
  • in the Bowman’s capsule
  • water reabsorbed from filtrate
  • in PCT/collecting duct
  • reabsorption of water because medulla is hypertonic
  • due to solutes reabsorbed by active transport
  • loop of Henle generates hypertonic conditions in medulla
  • ADH causes more water reabsorption by aquaporins
34
Q

Compare and contrast excretion in humans and unicellular organisms such as Paramecium. [3]

A
  • both expel CO2/nitrogenous waste
  • paramecium does not have special organs for excretion
  • Paramecium excrete through plasma membrane
  • Paramecium uses entirely passive transport (diffusion)
  • Paramecium excretes ammonia, humans excrete urea
35
Q

Describe the role in the menstrual cycle of one named hormone from the ovary and one from the pituitary. [2]

A
  • Pituitary: LH to trigger ovulation; FSH to stimulate follicle development
  • Ovary: Oestrogen to repair endometrium; Progesterone to maintain endometrium
36
Q

Outline two adaptations of capillaries for efficient exchange of substances with surrounding tissues. [2]

A
  • one-cell thick walls for shorter diffusion distance
  • gaps/porous walls for faster diffusion
  • small diamater/narrow for closer distance to most cells
37
Q

Outline the role of the right atrium in the cardiac cycle. [4]

A
  • collects deoxygenated blood from body
  • from the vena cava
  • pumps blood into the right ventricle
  • at the start of the cardiac cycle
  • sinoatrial node in right atrium to initiate heartbeat
  • SA node sends out electrical signal to stimulate contraction in the atria

IB Biology 22-24 (13 decks)

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