Biology #6 Human Physiology

What is the difference between cell respiration and ventilation?

Cell respiration is a chemical process (in the mitochondria and cytoplasm), releasing ATP for use. Ventilation is a mechanical process (in alveoli, where gas exchange takes place) taking in oxygen and removing CO2

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Name the different components of the respiratory system

nose/ mouth (respiratory passages), trachea, L & R bronchi, bronchioles, L & R lungs, alveoli, diaphragm, ribcage, intercostal muscles

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Outline the changes that happen during respiration

External intercostals contract, diaphragm contracts/flattens, thorax volume increases, thorax pressure decreases

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What is negative pressure breathing? (mammals have this)

Lung pressure is lower than atmospheric pressure

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What is ventilation rate and how can it be monitored?

Number of inhalations & exhalations per min. Can be monitored by data logging: measures pressure variations inside chest (due to chest expansions)

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What is tidal volume and how can it be monitored?

Volume of air taken in/ out with each inhalation/ exhalation. Monitored using a spirometer.

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What is vital capacity? What is residual volume?

The maximum capacity of the in/ out breath. The volume of air that never leaves the lungs

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What is the role of the pleural membrane in the intercostal muscles

Secretes lubricant called pulmonary surfactant which reduces friction so that lungs do not rub against ribs/ damage during ventilation & prevents lungs from collapsing

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What 4 adaptations allow for successful gas exchange?

1. large surface area 2. high conc. gradient 3. short diffusion pathway/ thin membrane 4. moist environment/ surface

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What are the 2 types of alveolar wall cells and what do they do?

Type 1 pneumocytes (approx 95% of cells): site of gas exchange, thin membrane & permeable. Type 2 pneumocytes: secrete fluid (containing pulmonary surfactant) which coats inner surface of alveoli, increasing efficiency of gas exchange.

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Why is it important that there is a dense network of blood capillaries around the alveoli?

To allow for immediate transport of exchanged gases to the blood/ body

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What are the causes and symptoms of lung cancer?

Causes: smoking (mutagens from tobacco), passive smoking, air pollution, radon gas, asbestos & silica (dust from these materials deposited in lungs) Symptoms: blood in phlegm, shortness of breath, fatigue, weight loss, chest pain, persistent coughing

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What is emphysema?

Caused by smoking, air pollution. Cilia are damaged so cannot expel mucus & infection builds. Damage to WBCs that normally fights infection. Damaged & inflamed cells/ WBCs release trypsin (a protease) which digests elastic fibres in alveolus walls.

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State the role of neurons (nerve cells)

To carry high speed messages in the form of electrical impulsesidentify what species of organism there are in an area being studied (in an ecological investigation)

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What is saltatory conduction?

When the impulse jumps from nod etc node, helps speed up transmission

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Outline the structure of neurons

Axon is surrounded by myelin sheath (consisting of Schwann cells) with small gaps called nodes of Ranvier, allowing nerve impulses to jump from node to node (saltatory conduction). Dendrites connect to other neurons.

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What are the 3 types of neurons?

1. Sensory (detect stimulus) 2.relay (connects to central nervous system) 3.motor (carrying out action i.e. contract muscle)

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Outline the role of Ca+ in electrical transmission in the nervous system

Nerve impulse reaches end of pre-S neuron 2. Ca+ enter via channels, causing depolarisation, triggering vesicles to fuse w memb & release NT via exocytosis

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What does the central nervous system (CNS) consist of? What are peripheral nerves?

CNS: Brain and spinal cord. Peripheral nerves connect all parts of the body to the CNS

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Define resting potential?

The electrical potential across a plasma membrane of a cell that is NOT conducting an impulse. -70mV

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Define action potential?

The reversal and restoration of an action potential across the plasma membrane of a cell aka the electrical impulse (...called depolarisation & repolarisation). +30mV

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Describe how an action potential crosses a synapse (5)

Depolarisation of pre-S.N. opens Ca+ channels. Ca+ enter & cause vesicles (w NT) to fuse w pre-S memb & release into cleft. NT bind w receptors on post-S memb. Triggers Na+ channels to open Na+ enter post-S.n. Flux of Na+ triggers depolarisation

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What are cholinergic synapses?

Synapses that use the NT, acetylcholine. This is broken down by cholinesterase to produce acetyl & choline. Choline is reabsorbed by pre-synaptic neuron.

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What do neonicotinoid pesticides do? Why are they harmful?

Used on plants/ crops. Block receptor sites of neurons in insects, paralysing & killing them. Harmful because it doesn't discriminate between species, so kills honeybees as well as insect pests (intended targets).

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Describe how local currents causes propagation (travelling) of the nerve impulse

Local currents (diffusion of sodium ions both inside & outside the membrane) triggers the resting potential in subsequent parts of the axon to in turn diffuse to action potential..?

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What does an oscilloscope trace show?

An action potential being transmitted in a nerve axon (including the resting potential, depolarisation [voltage peak] & repolarisation...back to resting potential)

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Between what range of millimoles must the blood glucose concentration be kept?

4 - 8 millimoles

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What cells are insulin & glycagon secreted from?

Islets of Langerhans (specialised tissue in the pancreas)... insulin= beta cells.... glycagon= alpha cells

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What is the role of insulin & glycagon (hint: of which adrenaline is the back up system)

Insulin: stimulates absorption of glucose by liver & muscle cells, turning glucose into glycogen by [glycogenesis] DECREASES b.g. levels. Glycagon: stimulates glycogenolysis (splitting glycogen into glucose). INCREASES b.g. levels.

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What is the difference between type 1 & type 2 diabetes?

T1: onset in childhood (congenital), non-functioning pancreas (beta cells destroyed), treat by IV injections. T2: acquired/ late onset (target cells become insensitive to insulin), lifestyle changes i.e. less carb in diet

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What are the risk factors for type 2 diabetes? (4)

high fat/ low fibre diet. obesity. little/ no exercise. genetic factors affecting fat metabolism.

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What is thyroxin, where is it secreted from & what is its role?

A hormone. Secreted by thyroid glands (in neck). Regulates body metabolism & helps control body temp. Targets almost all cells in body.

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Deficiency in what chemical element in the diet prevents synthesis of thyroxin?

Iodine (found in cranberries, milk, seaweed...)

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What part of the brain controls the secretion of hormones?

The hypothalamus

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Define homeostasis

The maintenance of a constant internal environment

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Where is leptin secreted from and what does it target?

A hormone secreted by adipose cells (fat storage cells), targeting the hypothalamus (contributes to control of appetite). This causes appetite inhibition (negative feedback) and reduced food intake

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After successful experiments of obese mice, what were the results of leptin supplements on obese humans? Reasons for this?

Volunteers didn't lose weight as expected; any loss was regained quickly after. Side effects: skin irritation. 1. human physiology differs from mice. 2. OB not insufficient secretion of leptin, but target cells in hypothalamus resistant to leptin?

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Where is melatonin secreted from and what is its role?

From pineal gland. Secreted in response to detection of light. Regulates sleep-wake/ circadian cycle. Removed from blood by the liver.

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Why do we get jet lag?

Because the body has not had enough time to adjust to the different light hours: circadian cycle still according to previous destination & melatonin still being secreted according to this cycle. Symptoms include sleep disturbance, fatigue, headaches

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What is the role of the ovaries in F and the testes in M?

F: produce eggs, oestrogen & progesterone. M: produces sperm & testosterone

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What is the role of the oviduct?

Collects eggs at ovulation & provides site for fertilisation, then moves embryo to uterus

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What is the role of the uterus for the foetus during pregnancy?

Provides protection, food, oxygen & removes waste products

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What kind of role does the cervix & ***** have?

Protection: cervix protects foetus (& dilates at birth). ***** protects internal parts of female reproductive system

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What is the role of the urethra in male & female reproductive systems?

M&F: transfers urine during urination. M: transfers semen during ***********

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What is the role of the scrotum?

Holds testes at lower than core body temperature

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What is the role of the epididymis?

Stores sperm until ***********

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What is the role of the prostate gland & seminal vesicle?

secrete alkaline fluid: added to sperm to make semen sticky & to help them swim after ***********

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What is the role of oestrogen?

Causes pre-natal development of F reproductive organs & secondary characteristics (i.e. breasts & pubic hair) during puberty

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What is the role of progesterone?

Prepares uterus during menstrual cycle for implantation of an embryo

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What is the role of testosterone?

Causes pre-natal development of M genitalia & secondary characteristics (growth of testes, penis & pubic hair, lowering of voice). Stimulates production of sperm from puberty onwards (positive feedback)

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How do gonads of embryos develop into M/ F reproductive organs?

XY chroms: SRY gene present: development of testes: male. ** chroms: SRY gene absent: development of ovaries: female.

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What is negative & positive feedback? Give an example of each

Neg: inhibitory (stabilises) e.g. body temp, blood pH & glucose. Pos: stimulatory (sudden rises/ falls) e.g. labour contractions, blood clotting (enzyme cascade), skin healing, breast milk production, ovulation

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State the main event that happens during each menstrual cycle

An oocyte (egg) matures inside a fluid-filled sack in the ovary called a follicle. The egg is released when the follicle bursts open during ovulation

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Outline stage 1: down regulation, in IVF

Female takes drug everyday (i.e. in form of nasal spray) to inhibit secretion of LH & FSH from pituitary gland. Causes secretion of oestrogen & progesterone to be also inhibited. This allows better control of superovulation.

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Outline stage 2: artificial doses of hormones, in IVF

high doses of FSH & LH hormones are injected daily over 10 days to stimulate development of follicles (up to 20!). This is called superovulation

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Outline stage 3: egg retrieval & fertilisation, in IVF

When follicles are 15-20mm in diameter, hCG injection stimulates them to mature. 36 hrs later, micropipette through uterus wall retrieves eggs from follicles. Eggs mixed with sperm in sterile conditions & then incubated if successful b4 implantation

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Outline stage 4: establishing a pregnancy, of IVF

F takes tablet of extra progesterone to ensure uterus lining is maintained & to aid implantation. 2 or 3 eggs are implanted, increasing success rate (which is only 40% if only 1 is implanted)

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What was the role of William Harvey in research into reproduction?

Falsified Aristotle's 'seed & soil' theory (M 'seed' forms egg when mixed w/ menstrual blood). However, he did not have the technology to observe microscopic gamete & early stages of embryo (esp. in deer/chicken, notorious for long gestation period)

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Suggest a way in which William Harvey could have done his research into reproduction with deer/ chickens differently?

Dissect the uterus of deer/ chickens at different stages in order to see development.

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Suggest M & F causes of infertility

F: eggs not maturing/ being released, abnormality in uterus prevents implantation. M: unable to ejaculate normally/ have erection, low sperm count/ abnormal sperm with low mobility (i.e. cannot swim)

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What happens during the follicular (first) phase? (2)

Menstruation: endometrium is shed. FSH increases, stimulating follicle development.

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What happens during the ovulatory phase? (4)

FSH & follicle stimulate oestrogen release. Oestrogen stimulates endometrium development. Oestrogen stimulates LH secretion. Peak in LH stimulates ovulation.

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What happens during the luteal (final) phase? (4)

Drop in LH causes corpus lute to form from now empty follicle. Corpus luteum releases progesterone. Progesterone maintains endometrium& inhibits FSH & LH. If no fertilisation occurs, progesterone & oes drop, triggering menstruation & FSH release.

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What is the order that hormones peak in the menstrual cycle?

FELP! ... FSH, (O)estrogen, LH, Progesterone

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Biology #6 Human Physiology

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