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Higher Human Biology > Physiology And Human Health > Flashcards

Physiology And Human Health Flashcards

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1
Q

Functions of the testes

A
  • produce sperm in seminiferous tubules

* produce testosterone in interstitial cells

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2
Q

_____ gland and seminal _____ secrete fluids that maintain _____ and ______ of sperm

A
  • prostate
  • vesticles
  • mobility
  • viability
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3
Q

Seminiferous tubules unite to form ___ ___

A

Sperm duct

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4
Q

What does semen contain?

A
  • Sperm from the testes
  • fructose from the seminal vesicles
  • enzymes from the prostate gland to maintain the mobility and viability of sperm
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5
Q

The male produces ____ (sperm cells) _______ from puberty until death and is said to display _____ ____[

A
  • gametes
  • continuously
  • continuous fertility
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6
Q

How is it possible for the male to display continuous fertility?

A

Because male sex hormone levels remain constant after puberty

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7
Q

What and where are eggs formed from?

A

Eggs are formed from germline cells in the ovaries

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8
Q

What do ovaries contain?

A

Immature ova (eggs) in various stages of development

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9
Q

What is each ovum surrounded by?

A

A follicle that protects the developing ovum and secretes hormones

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10
Q

Mature ova are released into the _____ where they may be fertilised by a sperm to form a _____

A
  • oviduct

* zygote

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11
Q

Describe the process of fertilisation

A

1) egg released from ovary
2) egg picked up by funnel of oviduct
3) egg moved along oviduct by hair- like cilia
4) sperm fertilised egg

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12
Q

At puberty, what does the hypothalamus in the brain secrete?

A

A released hormone whose target is the pituitary gland

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13
Q

What’s FSH?

A

Follicle-stimulating hormone

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14
Q

What 2 hormones does the pituitary gland produce when stimulated at puberty?

A

• FSH

and

  • ICSH in men
  • LH in women
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15
Q

What’s ICSH?

A

Interstitial cell-stimulating hormone

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16
Q

What’s LH?

A

Luteinising hormone

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17
Q

The release of hormones at puberty triggers the onset of ___ _____ in men and the _____ ____ in women

A

Sperm production

Menstrual cycle

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18
Q

What are hormones classed as?

A

Chemical messengers

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19
Q

What are hormones produced by?

A

Endocrine glands

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20
Q

Where are hormones secreted?

A

Directly into the bloodstream

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21
Q

When a hormone reaches a certain target tissue, what does it bring about?

A

A specific effect

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22
Q

When FSH arrives in the male’s bloodstream, it promotes ____ _____ in the seminiferous tubules

A

Sperm production

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23
Q

When ICSH arrives in the male’s bloodstream, it stimulates interstitial cells to produce the male sex hormone _____

A

Testosterone

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24
Q

What’s the influence of testosterone?

A
  • stimulates sperm production in seminiferous tubules

* activates prostate gland and seminal vesicles to produce their secretions

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25
Q

Describe the negative feedback control in the hormonal control of sperm production (simple)

A
  • decreases in levels of FSH and ICSH
  • decreases in testosterone levels
  • increase in levels of FSH and ICSH
  • increase in testosterone levels
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26
Q

Describe the negative feedback control in the hormonal control of sperm production (detailed)

A
  • As testosterone concentration increases in the bloodstream, it reaches a level where it inhibits the secretion of FSH and ICSH by the pituitary gland
  • This leads to a decrease in testosterone concentration
  • Once testosterone levels fall below a set point, the inhibition is lifted and the pituitary gland secretes FSH and ICSH again
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27
Q

What are the two phases of the menstrual cycle?

A
  • FOLLICULAR PHASE

* LUTEAL PHASE

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28
Q

Purpose of FSH in the follicular phase of the menstrual cycle

A
  • stimulates the development and maturation of each follicle
  • stimulates the follicle to secrete oestrogen
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29
Q

Purpose of oestrogen in the follicular phase of the menstrual cycle

A
  • stimulates proliferation of inner layer of uterus (endometrium) causing its repair following menstruation and preparing it for implantation
  • affects consistency of cervical mucus enabling it to be more easily penetrated by sperm
  • peak levels stimulate LH secretion by pituitary gland
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30
Q

What’s proliferation?

A

Cell division

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31
Q

What does the surge of LH trigger in the luteal phase of the menstrual cycle?

A

Ovulation

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32
Q

What does LH bring about the development of during the luteal phase of the menstrual cycle?

A

Development of the cuprous luteum from the follicle

Then stimulates the corpus luteum to secrete the sex hormone progesterone

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33
Q

What are oestrogen and progesterone known as?

A

The ovarian hormones

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34
Q

What does the progesterone released from the corpus luteum during the luteal phase of the menstrual cycle promote?

A

Promotes further development and vascularisation of endometrium into spongy layer rich in blood vessels, making it ready to receive a blastocyst if fertilisation occurs

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35
Q

What do peak levels of progesterone do in the luteal phase of the menstrual cycle?

A
  • inhibits secretion of FSH and LH by the pituitary gland

* concentrations of FSH and LH drop as a result and no new follicles develop at this time

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36
Q

What effect does the presence of fertilisation have on the luteal phase of the menstrual cycle?

A

If fertilisation does occur, the corpus luteum does not degenerate and progesterone levels remain high

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37
Q

What effect does the absence of fertilisation have on the luteal phase of the menstrual cycle?

A
  • lack of LH leads, in turn, to degeneration of corpus luteum by ~day 22 in cycle
  • This is followed by rapid drop in progesterone (and oestrogen)
  • by day 28 these ovarian hormones are at such a low level that the endometrium can no longer be maintained and menstruation begins
  • This involves the loss of the inner layer of the endometrium accompanied by a small volume of blood
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38
Q

Site of FSH production

A

Pituitary gland

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39
Q

One function of FSH in women

A

Stimulates the development and maturation of each follicle

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40
Q

Site of LH production

A

Pituitary gland

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41
Q

One function of LH

A

Brings about the development of the corpus luteum - stimulates ovulation

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42
Q

Site of oestrogen production

A

Ovary (released by developing follicle)

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43
Q

Functions of oestrogen

A
  • stimulates repair of endometrium

* stimulates secretion of LH by the pituitary gland

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44
Q

Site of progesterone production

A

Ovary ( released by corpus luteum)

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45
Q

One function of progesterone

A

Promotes further vascularisation of the endometrium

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46
Q

Describe the fertile periods in males

A
  • the negative feedback of testosterone maintains a constant level of FSH and ICSH in blood
  • This results in steady quantity of testosterone being secreted and sperm being produced, meaning men are continuously fertile
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47
Q

Describe the fertile period in females

A
  • The interplay of pituitary and ovarian hormones in the body results in a period of cyclical fertility
  • This is restricted to 1-2 days immediately following ovulation
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48
Q

Two ways to identify the fertile period in females

A
  • temperature

* mucus

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49
Q

Describe how temperature can be used to identify the fertile period in females

A
  • Approx 1 day after LH surge triggering ovulation, woman’s body temp rises by ~ 0.5*C under the action of progesterone
  • The infertile phase is resumed, on avg, after the 3rd daily recording of the higher temp by which time the unfertilised egg had disintegrated
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50
Q

Describe how mucus can be used to identify the fertile period in females

A
  • cervical mucus secreted into vagina during fertile period is thin and watery to allow sperm easy access to female reproductive system
  • After ovulation the mucus gradually increases in viscosity under the action of progesterone showing that the system had returned to infertile phase
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51
Q

Failure of the pituitary gland to secrete adequate FSH or LH may lead to a failure in _____

A

Ovulation

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52
Q

Ovulation can be successfully stimulated by?

A
  • drugs that mimic the normal action of FSH and LH
  • Drugs that prevent the negative feedback effect of oestrogen on FSH secretion during the Luteal phase of the menstrual cycle
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53
Q

Drugs that stimulate ovulation are so effective they can do what?

A

Can bring about multiple ovulation which can lead to multiple births or can be used to collect ova (eggs) for IVF programmes

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54
Q

What’s insemination?

A

The introduction of semen into the female reproductive tract

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55
Q

What’s artificial insemintion?

A

The insertion of semen into the female tract by some means other than sexual intercourse

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56
Q

When may artificial insemination be used?

A
  • man has low sperm count

* donor sperm when partner is sterile

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57
Q

Describe artificial insemination

A
  • if a man has a low sperm count, several samples of his semen can be collected over a period of time and preserved by freezing until required
  • They are then defrosted and released together (concentrated) into the partner’s reproductive tract at the time when she is most likely to be fertile
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58
Q

When can intracytoplasmic sperm injection be employed?

A

When the man has a very low sperm count or many of his mature sperm are defective in some way

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59
Q

What does intracytoplasmic sperm injection (ICSI) involve?

A

Drawing the head of a healthy sperm into a syringe needle and injecting it directing into an egg to bring about fertilisation.

The egg is held with a holding tool

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60
Q

What does IVF attempt to solve?

A

The problem of infertility caused by a blockage of the oviducts

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61
Q

What does IVF enable?

A

Enables fertilisation to occur outside the bodies of the potential parents in a culture dish (in vitro)

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62
Q

Describe In Vitro Fertilisation (IVF)

A

1) Woman given hormonal treatment to stimulate multiple ovulation
2) Eggs surgically removed - alternatively a sperm may be injected directly into an egg at this stage (ICSI)
3) Eggs are mixed with sperm and nutrients in a culture dish to allow fertilisation
4) Zygotes are incubated until they have formed at least 8 cells
5) 2/3 embryos inserted into mothers uterus for implantation
6) Remaining embryos are frozen

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63
Q

What can PGS and PGD be used in conjunction with?

A

IVF to identify abnormalities

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64
Q

What is Preimplantation genetic screening (PGS)

A

PGS is a non-specific approach that checks the embryo for single gene disorders and common chromosomal abnormalities in general

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65
Q

What’s Preimplantation genetic diagnosis (PGD)?

A

a specific approach that is used to check for a known chromosomal or gene defect

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66
Q

What do PGS and PGD enable?

A

These tests enable experts to select which embryos should and which should not be allowed to become implanted in the mothers endometrium

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67
Q

What’s contraception?

A

Contraception is the intention prevention of conception or pregnancy by natural or artificial means

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68
Q

What are barrier methods of contraception?

A
  • A barrier method makes use of a device that physically blocks the ability of sperm to reach an ovum
  • These methods are v effective but not as successful as chemical methods
  • Male/female condoms, diaphragm, cervical cap
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69
Q

What are male/female condoms?

A

A rubber sheath that fits over the man’s penis or covers the inside of the vagina

Both collect semen following ejaculation, preventing sperm reaching the uterus

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70
Q

What’s a diaphragm?

A

A dome shaped rubber cap that is inserted into the woman’s vagina to block the cervix before sexual intercourse

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71
Q

What’s a cervical cap?

A

A rubber structure that fits tightly around the cervix and can be left in position for a few days

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72
Q

What’s an intra-uterine device (IUD)?

A

A T-shaped structure that is fitted into the uterus for many months or years to prevent the implantation of an embryo into the endometrium

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73
Q

Describe the combined pill

A

These oral contraceptive pills normally contain synthetic progesterone and oestrogen

A pill is taken every day for 3 weeks from the final day of the previous menstrual period

High concentrations of progesterone and oestrogen exert -ve feedback control inhibiting FSH and LH secretion by the pituitary gland

As little or no FSH is present, follicle maturation remains inhibited and decreases levels of LH prevent ovulation

Dummy (placebo) pills are usually taken during the 4th week to allow the levels of oestrogen and progesterone to drop and menstruation to occur

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74
Q

Describe sterilisation procedures in males

A

In men vasectomy involves the cutting and trying of the two sperm ducts to prevent the release of sperm

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75
Q

Describe sterilisation procedures in women

A

In women tubal ligation involves the cutting and tying of the two oviducts to prevent eggs meeting sperm and reaching the uterus.

This is highly effective and irreversible

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76
Q

Describe the negative feedback control involving ovarian hormones

A

High concentrations of progesterone and oestrogen exert negative feedback control inhibiting FSH and LH secretion by the pituitary gland.

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77
Q

Describe ‘mini pills’

A

These are known as progesterone only pills because they contain synthetic progesterone but no oestrogen

They work by causing the thickening of cervical mucus which reduced the liability of sperm and their access to the uterus.

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78
Q

Describe morning after pills

A

Aka emergency contraceptive pills

They often contain higher doses of the hormones (P+Oe) found in standard oral contraceptive pills

They are taken by the woman after unprotected sexual intercourse to prevent ovulation or implantation if fertilisation has taken place unintentionally.

Ideally the pills should be taken as soon as possible after unprotected sex but it may be effective up to 72 hrs afterwards

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79
Q

What’s antenatal screening?

A

During pregnancy women undergo a variety of tests and procedures to monitor the health of themselves and the foetus.

Identifying risk of disorder so further tests and a potential diagnosis can be offered.

The standard tests include:
• a physical examination 
• check medical history for possible complications 
• blood pressure
• blood type + urine samples
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80
Q

What’s ultrasound imaging?

A

A scanner picks up high frequency sounds which bounce off the foetus and converts these to ultrasound images on a computer screen.

Two routine scans are carried out - dating scan and anomaly scan

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81
Q

Describe the dating ultrasound scan

A
  • carries out between 8-14 weeks

* tests for chemical markers are used to determine the stage of the pregnancy and calculate the due date

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82
Q

Describe the anomaly ultrasound scan

A
  • performed at 18-20 weeks when the foetus is longer

* check for any serious physical development abnormalities

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83
Q

Describe biochemical tests (pregnancy)

A

Biochemical tests are used throughout the pregnancy to ensure that the normal course of events is taking place.

With consent the mothers blood type is identified and regular blood and urine tests are carried out through pregnancy to monitor the concentrations of mother themselves eg HCG detection in the blood and urine is the basis of early pregnancy tests.

Tests for chemical markers

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84
Q

Describe the biochemical test for AFP

A
  • 16-18 weeks
  • woman offered test to check for AFP (alpha-feto protein concentration increases in the mothers bloods while pregnant)
  • low levels of AFP (<0.5) (0.5-2.49 is normal) are found in cases such as Down Syndrome
  • The result of this test in conjunction with the mothers age allow experts to asses the risk of chromosomal abnormalities present in the foetus.
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85
Q

Why is the timing of biochemical tests very important?

A

If carried out at the wrong time they can produce false positive or false negative results due to the natural changes in marker concentrations throughout the pregnancy

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86
Q

Why would a test of HCG concentration be meaningless at 10 weeks ( the elrory time)

A

In a normal pregnancy HCG concentration increased during weeks 6-10 and then decreases.

HCG conc. remains Hugh when the foetus has Down’s Syndrome.

A test at 10 weeks would lead to a false positive result ( test shows foetus has the condition when it does not)

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87
Q

What is diagnosis testing?

A

A definitive test used to establish whether or not a person is suffering from a specific condition or disorder

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88
Q

What’s a screening test?

A

A more general test not looking for a specific disorder

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89
Q

Why are diagnosis tests offered to pregnant women?

A

If:
• evidence of potential problems had emerged from screening tests

  • there is a history of genetic disorders in the family
  • she is in a high risk category eg over the age of 35
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90
Q

What are karyotypes generated from?

A

Diagnosis tests use foetal material taken from the mother during the pregnancy to generate a karyotype of the foetus

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91
Q

What is a karyotype?

A

A karyotype is a visual display of an individuals complete chromosome complement arranged in homologous pairs.

These tests have an associated risk of causing a miscarriage but have a very low error rate

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92
Q

What’s the name of the process where a sample of fluid is extracted from the mothers uterus to generate a karyotype?

A

Amniocentesis procedure

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93
Q

How is a karyotype generated?

A

The cells removed by the amniocentesis procedure are cultured, stained and examined under the microscope.

A full chromosome compliment is photographed and the chromosomes arranged into pairs to form the karyotype.

Results take about 2 weeks and allow the diagnosis of a range of conditions

Eg a karyotype containing an extra copy of chromosome 21 indicates Down Syndrome

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94
Q

What’s chronic villus sampling?

A

CVS takes a sample of placental cells using a tube inserted into the reproductive tract.

Can be carried out as early as 8 weeks into the pregnancy

The cells are cultured and karyotyped as before.

The prospect of termination at this earlier stage may be less traumatic for parents that the incidence of miscarriage is higher at 2%

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95
Q

What are autosomes?

A

All other chromosomes in the genotype other than the sex chromosomes

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96
Q

What genes does autosomal recessive inheritance affect?

A

The affected gene is on an autosome and is a recessive allele

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97
Q

Patterns of autosomal recessive inheritance

A
  • rarely expressed in the phenotype
  • skips generations
  • males + females approx equally affected
  • all sufferers are homozygous recessive
  • non sufferers are homozygous dominant or heterozygous
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98
Q

Example of autosomal recessive inheritance

A

Cystic fibrosis

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99
Q

What genes are affected by autosomal dominant inheritance?

A

The affected gene is on an autosome and is a dominant allele

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100
Q

Autosomal dominant patterns of inheritance

A
  • the trait appears in every generation
  • all sufferers have an affected parent
  • males + females equally affected
  • all non sufferers are homozygous recessive
  • sufferers are either homozygous dominant or heterozygous
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101
Q

Example of autosomal dominant inheritance

A

Huntington’s Disease

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102
Q

Autosomal incomplete dominance pattern of inheritance

A
  • the fully expressed form of condition occurs rarely
  • each sufferer of fully expressed form has 2 parent who have the partly expressed form
  • the partly expressed form occurs more frequently
  • males + females affected equally
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103
Q

Example of autosomal incomplete dominance

A

Sickle cell anaemia

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104
Q

What are sex linked genes?

A

Many genes of the females second X chromosome which are absent from the males Y

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105
Q

Pattern of inheritance when the affected gene is on the X chromosome and is a recessive allele

A
  • more males affected
  • no sons of affected males would show the trait
  • some grandsons of an affected male would show the trait
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106
Q

Example of sex linked recessive inheritance

A

Haemophilia

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107
Q

What does the heel prick test screen newborn babies for?

A

PKU

Hyperthyroidism

CF

Galactosaemia

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108
Q

What is PKU caused by?

A

A substation mutation which results in a genetic error in metabolism

The enzyme which converts phenylalanine to tyrosine if non functional

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109
Q

How are PKU patients treated?

A

Treating PKU patients with a phenylalanine restricted diet prevents irreversible damage to mental development.

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110
Q

What’s the cardiovascular system composed of?

A
  • blood
  • blood vessels
  • the heart which circulated blood around the system
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111
Q

What’s the pulmonary system?

A

Circulated blood from heart to lungs and back to heart

112
Q

What’s the systemic system?

A

Circulates blood from the heart to the body and back

113
Q

What’s the hepatic portal vein?

A

Carried blood from intestines to liver

114
Q

What do blood vessels do?

A

Transport blood around the body

115
Q

What’s the lumen of a blood vessel lined with?

A

A thin layer of epithelial cells called the endothelium

116
Q

What does blood consist of?

A

Red blood cells

White blood cells

Platelets bathed in plasma

117
Q

What is plasma?

A

A watery, yellowy fluid that contains many dissolved substances such as glucose, amino acids, respiratory gases, plasma proteins and useful ions

118
Q

Where do arteries carry blood?

A

Away from the heart

119
Q

Blood in the arteries is at ____ pressure

A

High

120
Q

What do arteries consist of?

A

Arteries have an outer layer of connective tissue containing elastic fibres and a thick middle layer containing smooth muscle with more elastic fibres

121
Q

What do the elastic fibres in arteries enable?

A

Enable the walls of the arteries to stretch and recoil accommodating the surge of blood after each heart contraction

122
Q

What does the the thick muscle layer of an artery allow?

A

Allows the artery to withstand the high pressure produced

123
Q

What do arteries branch off into?

A

Smaller arterioles

124
Q

What’s vasoconstriction and vasodilation?

A

The smoothie muscle in the walls of arterioles can contract or relax to control blood flow depending on the body’s requirements

125
Q

Example of vasoconstriction and vasodilation

A

During strenuous exercise arterioles leading to working muscles undergo vasodilation.

At the same time the arterioles leading to the small intensity undergo vasoconstriction, reducing blood flows to these parts

126
Q

What are capillaries?

A

Capillaries are microscopic exchange vessels with all exchanges of substances between blood and living tissues taking place through their thin walls

127
Q

What are capillaries composed of?

A

Endothelium

Only one cell thick

128
Q

Describe blood flow through the blood vessels

A

Heart -> arteries -> arterioles -> capillaries -> ventless -> veins

129
Q

Where do veins carry blood?

A

Back to the heart

130
Q

What are veins composed of?

A

They have an outer layer of connective tissue containing elastic fibres

The muscular layer and layers of elastic fibres are thinner than those in an artery because blood flows at lower pressure.

Valves

131
Q

Why do veins contain valves?

A

To prevent the back flow of blood

132
Q

How does tissue fluid differ from plasma?

A

It contains no plasma proteins

133
Q

Why does tissue fluid not contain plasma proteins?

A

Protein molecules are too large to be filtered through the capillary wall

134
Q

How are gases exchanged between tissue fluid and cells?

A

Tissue fluid contains a high concentration of glucose, dissolved oxygen etc

These substances diffuse down a concentration gradient into nearby cells, supplying their requirements.

At the same time, carbon dioxide and other metabolic wastes diffuse out of the cells into the tissue fluid for excretion

135
Q

Where does most of the tissue fluid return to the blood?

A

In the capillaries at the venous end of the capillary bed

136
Q

What is excess tissue fluid absorbed by?

A

Thin walled lymphatic vessels

137
Q

Once in a lymphatic vessel what is tissue fluid called?

A

Lymph

138
Q

Describe lymphatic system

A

Lymph is collected by a vast network of tiny vessels which unite to form larger vessels

Lymphatic vessels return the lymph to circulatory system where it’s eventually passed onto cardiovascular system through two lymphatic ducts at the subclavian veins at each arm

139
Q

Why is the lymphatic system regarded as a specialised part of the cardiovascular system?

A

As it consists of:

  • lymph fluid derived from blood
  • system of vessels that returns lymph to blood
140
Q

What is the flow of lymph enabled by?

A

Enabled by compression when muscles contract during breathing and body movements

141
Q

What is the back flow of lymph prevented by?

A

Valves in the larger vessels

142
Q

Which side of the heart is the tricuspid valve on?

A

Right

Tri before you bi

143
Q

What side of the heart is the bicuspid valve on?

A

The left

Tri before you buy

144
Q

Describe blood flow through the heart

A

Body-> vena cava -> right atrium -> tricuspid valve -> right ventricle -> semi-lunar valve -> pulmonary artery -> lungs

Lungs-> pulmonary vein -> left atrium -> bicuspid valve -> left ventricle -> semi-lunar valve -> aorta -> body

145
Q

What’s heart rate?

A

Pulse - no.of heartbeats/ minute

146
Q

What’s stroke volume?

A

Vol. of blood expelled by each ventricle on contraction

147
Q

What’s cardiac output?

A

Vol. of blood pumped through each ventricle/ minute

148
Q

Formula for cardiac output?

A

Heart rate x Stroke volume

149
Q

How would u increase cardiac output?

A 
Increase stroke volume
or
Increase heart rate
or 
Increase both
150
Q

What’s the average length of the cardiac cycle?

A

0.8s based on a heart rate of 75bpm

151
Q

What’s the cardiac cycle?

A

The pattern of contraction (systole) and relaxation (diastole) shown by the heart during one complete heartbeat

152
Q

What are the 4 stages of the cardiac cycle?

A

1) Diastole (relax)
2) Atrial systole (contraction)
3) Ventricular systole (contraction)
4) Diastole (relax)

153
Q

Describe the first diastole of the cardiac cycle

A
  • during diastole the return of blood (via the vena cava and pulmonary artery) to the atria causes the volume of blood and the pressure in the atria to increase
  • when atrial pressure exceeds that in the ventricles the AV valves are pushed open and blood starts to enter the ventricles
154
Q

Describe the atrial systole (contraction) of the cardiac cycle

A
  • During atrial systole the two atria contract simultaneously and send the remaining blood down into the ventricles through the open AV valves
  • the ventricles full up with blood
  • the semi lunar valves remain closed
155
Q

Describe ventricular systole (contraction) of the cardiac cycle

A
  • The AV valves close
  • The pressure exerted on the blood in the ventricles (as the cardiac muscle contracts) soon exceeds the blood pressure in the arteries
  • The SL valves are pushed open
  • Blood is pumped out of the ventricles, through the SL valves and into the aorta and pulmonary arteries
156
Q

Describe the second diastole of the cardiac cycle

A

• during diastole the higher pressure of blood in the arteries closed the SL valves again and the next cardiac cycle begins

157
Q

What is responsible for the heart sounds heard with a stethoscope?

A

The opening and closing of the AV and SL valves

158
Q

The heartbeat originates in the heart but is regulated by what?

A

Both nervous and hormonal control

159
Q

The sequence of events that occur during each heartbeat is brought about by the activity of the ________ and the _____ _____ of the heart

A

Pacemaker

Conducting system

160
Q

What is the pacemaker know as?

A

The sino-atrial node (SAN)

161
Q

Where is the sino-atrial node (SAN) located?

A

In the wall of the right atrium

162
Q

What sets the rate at which the heart contracts at?

A

The auto-rhythmic cells in the SAN

163
Q

How do the auto-rhythmic cells in the SAN set the rate at which the heart contracts at?

A

By initiating electrical impulses that make cardiac muscle cells contract

164
Q

What regulates the rate of the SAN and how?

A

The medulla regulates the rate of the SAN through the antagonistic action of the autonomic nervous system

165
Q

What’s the autonomic nervous system (ANS)?

A

This is the part of the nervous system responsible for control of those bodily functions which are not consciously directed

Eg breathing, heartbeat + digestive processes

166
Q

Describe how the cardiac conducting system works

A
  • the timing of the cardiac muscle cell contraction is controlled by impulses from SAN spreading through the atria causing atrial systole
  • the impulse is picked up by the AVN (located in the centre of the heart)
  • Impulses from the AVN travel down the conducting fibres in the central wall of the heart which divide into left and right branches
  • Each branch is continuous with a network of tiny fibres in the ventricle walls and stimulation causes ventricular systole from the apex upwards
167
Q

How does the cardio-accelerator centre send it’s never impulses and what does it result in?

A

Via a sympathetic nerve to the heart

Increase in heart rate

168
Q

How does the cardio-inhibitor centre send its information and what does it result in?

A

Via a parasympathetic nerve

Decrease in heart rate

169
Q

What is the actual rate at which the heart beats determined by?

A

Which system (cardio accelerator centre/ cardio inhibitor centre) exerts the greater influence over the heart at any given moment

170
Q

What does an electrocardiogram (ECG) detect?

A

Tiny currents generated by the electrical activity of the heart

171
Q

What is the P wave of an ECG?

A

Wave of electrical excitation spreading across the atria from the SAN- atrial systole

172
Q

What is the QRS complex of an ECG?

A

Wave of excitation passing through the ventricles - ventricular systole

173
Q

What’s the T wave of an ECG?

A

Electrical recovery of the ventricles - diastole

174
Q

What are the two branches of the autonomic nervous system?

A

Sympathetic

Parasympathetic

175
Q

What does the sympathetic nerve of the ANS do?

A

Releases noradrenaline which increases heart rate

176
Q

What does the parasympathetic nerve of the ANS do?

A

Releases acetylcholine which decreases heart rate

177
Q

What is blood pressure?

A

The force exerted by blood against the walls of the blood vessels

178
Q

What’s blood pressure measured in?

A

Millimetres of Mercury (mmHg)

179
Q

What’s blood pressure generated by

A

The contraction of the ventricles

180
Q

Where is blood pressure at its highest?

A

The large elastic arteries (aorta and pulmonary artery)

181
Q

During ____ ____ the pressure of blood rises to a maximum (____mmHg)

A

Ventricular systole

120

182
Q

During ____ ____ blood pressure drops to a minimum (__mmHg)

A

Ventricular diastole

80

183
Q

Why is there a progressive decrease in blood pressure as it travels round the circulatory system?

A

Due to friction between the blood and the vessel wall and resistance from the vessel walls to blood flow

184
Q

How can systolic and diastolic pressure be measured?

A

Using a sphygmomanometer in mmHg

185
Q

What is a typical blood pressure reading for an adult?

A

120/80 mmHg

186
Q

Describe how blood pressure is measure using a sphygmomanometer

A
  • the cuff is inflated until the pressure drops blood flowing through the artery
  • the inflatable cuff deflated gradually
  • the blood starts to flow (detected by a pulse) of systolic pressures
  • the blood flows freely through the artery (and a pulse is not detected) at diastolic pressure
187
Q

What is hypertension?

A

High blood pressure

188
Q

What does high blood pressure result in?

A

The prolonged elevation of blood pressure at rest

189
Q

What is hypertension indicated by?

A

Systolic values >140mmHg and diastolic values >90mmHg

190
Q

What is hypertension a major risk factor for?

A

Many diseases including coronary heart disease and stroke

191
Q

Hypertension can be found in people with an unhealthy lifestyles that includes:

A
  • being overweight
  • not taking enough exercise
  • smoking
  • a diet high in fatty foods
  • consuming too much salt
  • regularly drinking alcohol to excess
  • being under continuous stress
192
Q

What is the process of atherosclerosis?

A

The accumulation of fatty material (consisting mainly of cholesterol), fibrous material, and calcium forming an atheroma or plaque beneath the endothelium

193
Q

What happens as the atheroma grows?

A

The artery thickens and loses it’s elasticity

The diameter of the artery becomes reduced and blood flow becomes restricted resulting in an increased blood pressure

194
Q

Atherosclerosis is the root cause of various cardio vascular diseases including?

A

Angina

Heart attack

Stroke

Peripheral vascular disease

195
Q

What do the coronary arteries do?

A

Supply the heart muscle with oxygen and nutrients

196
Q

Restriction/ blockage of the coronary blood supply results in what?

A

Angina - crushing chest pain radiating down left arm and up to the neck and jaw

197
Q

What can complete occlusion (blockage) of the coronary arteries cause?

A

A heart attack (myocardial infraction if left untreated)

198
Q

What is blood clotting?

A

A protective device triggered by damage to cells to prevent blood loss from a wound

199
Q

When may thrombosis be triggered?

A

When an arithmetic ruptured damaging the endothelium

200
Q

What’s thrombosis?

A

The formation of a clot (thrombus)

201
Q

What does thrombin (active enzyme) produce?

A

Fibrinogen (soluble)
And
Fibrin (insoluble)

202
Q

What do fibrin threads do?

A

Become interwoven into a framework to which platelets adhere, forming a blood clot

203
Q

What is a thrombus?

A

A blood clot

204
Q

What does thrombosis restrict?

A

Further restricts blood flow in addition to that cause by atheromas

205
Q

If a thombus breaks loose what is it referred to?

A

An embolus

206
Q

What does an embolus do?

A

It travels through the bloodstreams until it blocks a smaller blood vessel causing blood flow to be severely restricted or halted

207
Q

A thrombosis in a coronary artery can lead to what?

A

A heart attack (myocardial infarction- MI)

208
Q

A thrombosis in an artery in the brain can lead to what?

A

A stroke

209
Q

What happens to cells when thrombosis occurs?

A

Cells are deprived of oxygen leading to the death of tissues

210
Q

What is peripheral vascular disease?

A

Narrowing of the arteries due to atherosclerosis of arteries other than those of the heart or brain

211
Q

Which arteries are most commonly affected by peripheral vascular disease?

A

The arteries to the legs

212
Q

What is a deep vein thrombosis?

A

A DVT is a blood clot (thrombus) that forms in a deep vein in the lower leg, causing the affected area to swell and become painful

213
Q

What’s a pulmonary embolism?

A

When a clot from a deep vein breaks free and is transported via the vent cava and heart chambers to the pulmonary artery where it may block a small arterial branch

214
Q

What’s the treatment for pulmonary embolism?

A

Anti-coagulant drugs (heparin) or in severe causes thrombolytic drugs (streptokinase) to dissolve the clot

215
Q

What is cholesterol?

A

A lipid (fat)

A component of cell membranes and is used to make hormones eg the sex hormones testosterone, oestrogen, and progesterone

216
Q

A diet high in _____ ___ or ______ causes an increase in blood cholesterol levels

A

Saturated fats

Cholesterol

217
Q

Foods that include saturated fats and cholesterol?

A

Animal fat eg cheese, eggs, beef, pork, poultry

218
Q

What are lipoproteins?

A

Molecules containing a combination of lipid and protein and are found in the blood plasma

219
Q

What’s the role of lipoproteins?

A

To transport cholesterol from one part of the body to another

220
Q

What are Low-density lipoproteins?

A

Produced in liver

Transport cholesterol to body cells that need it

221
Q

What do LDL receptors do?

A

Attach to LDL cholesterol and engulf it in to the cell where it releases the cholesterol for use

222
Q

What happens once a body cell has sufficient cholesterol?

A
  • A negative feedback system is triggered
  • This inhibits the synthesis of new LDL receptors
  • Less LDL cholesterol can be absorbed from the blood by body cells resulting in deposits forming on arterial walls producing an atheroma
223
Q

What do High Density Lipoproteins do? (HDL)

A

Made in liver

Transport excess cholesterol from body cells back to the liver for elimination of preventing the accumulation of cholesterol in the blood

224
Q

HDL cholesterol is not taken into ____ ____ and does not contribute to _______

A

Artery walls

Atherosclerosis

225
Q

What will a higher ratio of HDL to LDL result in?

A

Lower blood cholesterol and a reduced chance of atherosclerosis

226
Q

Regular physical activity tends to ___ HDL levels

A

Raise

227
Q

How do drugs such as statin reduce blood cholesterol?

A

By inhibiting an enzyme essential for the synthesis of cholesterol by liver cells

228
Q

As more cholesterol originated from manufacture in the liver than from the diet, a ___ in cholesterol production by the liver soon results in a drop in ___ ______ level

A

Drop

Blood cholesterol

229
Q

Statin also increases the no. of __ ____ which bring about a reduction in the level of __ ______ in the blood

A

LDL receptors

LDL cholesterol

230
Q

What does chronic elevation of blood glucose levels lead to?

A

The endothelium cells taking in more glucose than normal, damaging the blood vessels

231
Q

What may atherosclerosis developing lead to?

A

Cardio vascular stroke

Peripheral vascular disease

232
Q

What may small hard vessels (arterioles and venues) damaged by elevated glucose levels result in?

A

Haemorrhage of blood vessels in the retina, renal failure or peripheral nerve disfunction

233
Q

What happens in vascular disease

A
  • endothelial cells lining arterioles become thicker and weaker
  • walls lose their strength and may burst and bleed into surrounding tissues, reducing blood flow through the body reducing blood supply
234
Q

Describe vascular disease in the retina

A

Diabetic retinopathy from prolonged high blood pressure causes small vessels in the eye to haemorrhage

Left untreated it can cause blindness

235
Q

Describe vascular disease in the kidneys

A

Damage to arterioles can cause renal failure as kidneys are no longer able to effectively filter and purify blood leading to…

  • ankle swelling
  • dark urine containing blood
  • shortness of breath on exercise
236
Q

Describe vascular disease in peripheral nerves

A

Peripheral neuropathy neves are damaged due to prolonged exposure to high glucose levels and can take form of numbing, tingling, or pain in the hands, arms, toes + feet

If left untreated can lead to development of ulcers + eventually amputation

237
Q

Glucose is need as a _____ ____ by all living cells

A

Respiratory substrate

238
Q

To generate a regular supply of glucose present in the bloodstream, the body employs a system of ____ ____ ____

A

Negative feedback control

239
Q

What cells detect a rise in blood glucose concentration (following a meal)?

A

Receptor cells only the pancreas

240
Q

What do receptor cells in the pancreas produce?

A

Insulin or glucagon

241
Q

What does insulin do?

A

Activates the conversion of glucose to glycogen in the liver decreasing blood glucose concentration

242
Q

What cells detect a drop in blood glucose concentration (following fasting)

A

Receptor cells in the pancreas

243
Q

What does glucagon do?

A

Activated the conversion of glycogen to glucose in the liver increasing blood glucose concentration

244
Q

Insulin and glucagon act ________

What does this mean?

A

Antagonistically

This means they counteract each other/ act against each other

245
Q

During exercise or fight/flight responses the body requires what?

A

Additional supplies of glucose to quickly provide energy

246
Q

During exercise or fight/flight responses how are glucose concentrations in the blood raised?

A

By adrenaline released from the adrenal glands

247
Q

What releases adrenaline?

A

The adrenal glands

248
Q

What does adrenaline do?

A

It overrides normal homeostatic control inhibiting the secretion of insulin and promoting the secretion of glucagon thereby increasing blood glucose concentration

249
Q

When does type 1 diabetes occur?

A

In childhood

250
Q

What is type 1 diabetes?

A

Cells have the normal number of insulin receptor cells but the pancreas is unable to produce insulin

251
Q

How can type 1 diabetes be treated?

A

Regular injections of insulin

252
Q

When does type 2 diabetes occur?

A

Develops later in life

Sufferers are usually overweight or obese

253
Q

What is type 2 diabetes?

A

The pancreas produces insulin but body cells are less sensitive to it

This insulin resistance is linked to a decrease in the number of insulin receptors in the liver, leading to a failure to convert glucose to glycogen

254
Q

How can be type 2 diabetes be treated?

A

By diet control, exercise and weight loss

255
Q

In both types of diabetes, blood glucose concentrations will ___ _____ after a meal

A

Rise rapidly

256
Q

In both types of diabetes, what happens when blood glucose concentrations rise rapidly after a meal?

A

The kidneys are unable to cope and kidney filtrate is so rich in glucose that it is not absorbed back into the blood and is excreted in urine.

257
Q

What is often used as an indicator for diabetes?

A

Testing urine for the presence of glucose

258
Q

Describe a glucose tolerance test

A

This is a clinical test used to diagnose diabetes

The blood glucose concentrations of an individual are measured after fasting

They consume a known mass of glucose and changes in their blood glucose concentrations are monitored for at least the next 2 hrs

The results are plotted to give a glucose tolerance curve

259
Q

What’s obesity?

A

Obesity is characterised by an accumulation of excess body fat in relation to lean body tissue (muscle)

260
Q

Why is obesity a major risk factor for?

A

Cardiovascular disease

Type 2 diabetes

261
Q

What’s the most common cause of obesity?

A

Excessive consumption of food rich in fats and free sugars combined with lack of physical activity

262
Q

How is body mass index (BMI) calculated?

A

Body mass (kg)
———————-
Height (m)^2

263
Q

A BMI greater than __ is used to indicate obesity

A

30

264
Q

What is a skin fold calliper?

A

Used to measure the thickness of a fold of skin containing a layer of subcutaneous fat at 4 specific sites in the body

265
Q

___ shaped people with excess _____ fat are known to be at a greater risk of CVD and type 2 diabetes than ____ shapes people with excess fat around their ___

A

Apple

Abdominal

Pear

Hips

266
Q

Women are considered to be at risk when the waist/hip ratio is > ___

A

0.8

267
Q

Men are considered to be at risk when the waist/hip ratio is > ___

A

1.0

268
Q

Obesity is linked to what?

A

High fat diets
+
A decrease in physical activity

269
Q

The energy intake in the diet should limit ___ and ___ ____ as fats have a high _____ value per gram and free sugars require no _____ ____ to be expended in their digestion

A

Fats

Free sugars

Calorific

Metabolic energy

270
Q

What are some risk factors of CVD?

A
  • physical inactivity
  • Diabetes
  • Obesity
  • Excess alcohol
  • Smoking
  • Diet high in saturated fat
  • High blood pressure
  • Stressful lifestyle
  • High LDL-cholesterol
271
Q

Exercise increases ___ ______ and preserves ___ tissue

A

Energy expenditure

Lean

272
Q

How can exercise help reduce risk factors for CVD?

A
  • keeping weight under control
  • minimising stress
  • reducing hypertension
  • improving blood lipids profiles (raises HDL)
273
Q

Describe the results of a glucose tolerance test on a non diabetic

A

Rise to max around 30 mins, quickly drops to initial level within 2.5 hrs. Insulin production is normal

274
Q

Describe the glucose tolerance test results for mild diabetes

A

Normal fasting level, rises to a max around 60 mins before decreasing. Delay in insulin response indicates mild diabetes. Diet controlled.

275
Q

Describe the glucose tolerance test results for severe diabetes

A

After fasting, glucose still abnormally high and continued to rise. Indicates severe diabetes - little or no insulin produced.

Higher Human Biology (3 decks)

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