Behaviour

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Behaviour Populations
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Contents

• Patterns of Behaviour
• Reproductive Behaviour
• Pregnancy
• Human Growth and Development
• Human Populations and Health

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Patterns of Behaviour
Intermediate neurones
Sensory neurones
Motor neurones
Predominantly in nervous tissue
Myelinated neurones Myelin sheath speeds up
impulse
Non-myelinated neurones No myelin sheath
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Patterns of Behaviour

• Glial cells
• - packed between neurones to form neuroglia
  tissue
• a) provides mechanical support and electrical
  insulation
• b) Schwann cells are specialised glial cells,
  forming myelin sheaths
• c) control nutrient and ionic balance. Break
  down neurotransmitters
• Nissl tissues
• - contained in neurones
• a) generate enzymes involved in impulse
  transmission and synthesis of trophic factors
• b) regulate growth and differentiation of
  nervous tissue

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Patterns of Behaviour

• When impulse is not transmitted
• - charge (resting potential) across axon
  membrane -70mV
• When impulse is transmitted
• - action potential is a brief reversal of
  resting potential
• All-or-None rule
• - stimulus needs the minimum intensity to
  initiate an action potential. Below this, there
  is no impulse
• Impulse takes place over
• - temporal or spatial summation

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Patterns of Behaviour

• Synapses
• - are gaps between neurones to control impulses
  chemically
• - release neurotransmitters that diffuse across
  synaptic cleft and trigger action potential in
  membrane
• - once it reaches post-synaptic neurone, enzymes
  break it down and it diffuses back across synapse
• Neurotransmitters used in the human body are
• - acetylcholine (motor neurones)
• - noradrenaline (sympathetic synapses)
• - serotonin, dopamine (in brain)

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Patterns of Behaviour

• Part of human brain responsible for regulation of
  heart beat rate
• Alters heart rate during exercise and body trauma
• Increases stroke volume of heart
• Sufficient amount of blood then reaches tissue
• Adrenaline and other hormones affect the
  cardiovascular centre and cause it to increase
  the rate of impulses which in turn increases the
  heart beat rate

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Reproductive Behaviour

• Either able to breed year round, or in breeding
  seasons
• Mammals
• Gametes are
• - male small and motile, produced in large
  quantities
• - female large and less motile, few produced
• Gametogenesis
• - male sperm production spermatogenesis
• - female egg formation oogenesis
• Female mammals have two cycles
• oestrous cycle and menstruation cycle

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Reproductive Behaviour

• oestrous cycle
• - ovulation, female is most fertile
• Menstruation cycle
• - uterus lining thickens during reproduction
  cycle
• - if fertilisation does not occur, lining breaks
  down
• menstruating mammals ? discharged as blood
  through vagina
• non-menstruating mammals ? reabsorbed, no
  bleeding
• - discharge of blood menstruation

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Reproductive Behaviour

• Menstrual Cycle
• - controlled by hormones over duration of
  approx. 28 days
• - 3 main phases follicular, ovulatory, luteal
• Follicular 1st part of menstrual cycle
  follicles start to develop into mature female
  gamete. Follicle cells surround developing egg
  cell and produce hormones that trigger other
  responses
• Ovulatory oocyte is released from ovary and
  passes down fallopian tube into uterus
• Luteal most follicle cells remain after
  ovulation and continue to develop and form a
  structure, corpus luteum ? more hormones are
  released

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Reproductive Behaviour
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Menstrual Hormones

• Oestrogen Promotes development maintenance of
  female reproductive structures (especially
  endometrial lining). Assists control of fluid
  electrolyte balance within the body. Prepares the
  follicle for the release of an egg
• Progesterone Secreted at ovulation, helps to
  prepare endometrium for implantation of an egg,
  prepares mammary glands for milk production.
  Primarily concerned with the procreation and
  survival of the foetus
• FSH  Stimulates follicles to ripen several eggs.
  At the same time the ovaries release oestrogen
• LH Further develops the follicles, triggers
  ovulation stimulates production of other
  hormones necessary for post ovulatory stage of
  cycle. Secretion of hormones is complex

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Male Gamete

• Structure of a Mature Sperm Cell
• - Head acrosome (enlarged lysosome ? digestive
  enzymes ? penetrate egg), nucleus
• - Middle piece mitochondria, ATP needed for
  tail movement
• - Tail flagellum, movement

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Fertilisation

• Sperm ejaculated into the vagina
• Alkalinity of semen neutralises acidic pH in
  vagina
• Mucus allows sperm to swim through cervix
• Wall of uterus has two distinct layers
• Bulk of uterus wall consists of myometrium (?
  smooth muscle which expels foetus at birth)
• - Active muscular contractions during
  intercourse support sperm
• - Travel to oviduct in 5hrs / survival rate of
  sperm 48hrs
• Endometrium is concerned with anchorage
  nourishment of embryo
• Sperm acquire ability to fertilise oocyte by
  removal of acrosome membrane proteins which takes
  6hours
• Fertilisation occurs in the fallopian tube, whose
  walls are lined with ciliated epithelia contain
  smooth muscles
• Contact between sperm and oocyte is by chance

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Early Development Week 1

• Ovulation releases ovum/secondary oocyte
• Fertilisation in the oviduct produces zygote
• As zygote moves along oviduct ? produces morula
• - As zygote divides, cells become smaller
• - Movement by cilia and peristalsis present in
  oviduct walls
• Morula develops into a blastocyst
• - Trophoblast (outer layer of blastocyst)
  nourishes future embryo
• - Inner cell mass will become foetus
• - Fluid filled cavity for protection (absorbs
  shocks, resists compression, ...)
• Blastocyst (100cells) implants itself in uterus
  lining
• - Nourished by secretion from uterus
• - Microvilli provide large surface area (? gas
  nutrients exchange)

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Early Development Week 2

• Trophoblast secretes enzymes ? digest tissues and
  blood vessel of endometrium
• Embryo uses released nutrients/products from
  digestion
• Blastocyst becomes buried within endometrium
• Microvilli are replaced by placenta
• Trophoblast secretes human chorionic
  gonadotrophin (hCG) hormone

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Development of Foetus

• During gestation (length of pregnancy) growth
  rate is in excess
• Placenta is the first organ to develop when
  blastocyst embeds itself in uterine lining
• Growth faster than embryo in early pregnancy
• Development increases in complexity
• Differentiating of inner cell mass of blastocyst
• First month ? beginning of a gut, developed
  kidney, brain, beating heart
• Second month ? all main organ systems present
  embryo is called a foetus
• At the end of gestation, placenta is discarded
  but essential for the 1st 9 months of life

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Circulatory System of Foetus

• Fetal lungs are non-functional ? placenta is used
  instead
• Umbilical vein carries oxygenated blood from
  placenta to vena cava
• Blood in the heart bypasses through foramen ovale
  
• Oxygenated blood flows from right into left atria
  / flap valve prevents back flow of blood
• Some blood in right atria passes to right
  ventricle into pulmonary artery (to lungs)
• Blood bypasses lungs through ductus arteriosus
• Oxygenated blood flows from pulmonary artery into
  aorta
• Umbilical arteries carry deoxygenated blood from
  aorta to placenta

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Structure of Foetus

• Exchange of substances between maternal and
  foetal blood
• O2 and waste products (urea, CO2) cross placenta
  by diffusion
• Glucose enters foetal blood by facilitated
  diffusion
• Amino acids enter foetal blood by active
  transport
• - Placenta contains many mitochondria
• Maternal antibodies are taken into villi by
  pinocytosis
• - Infant has immunity to same diseases as its
  mother after birth
• Secretes hCG (oestrogen, progesterone) ?
  maintains pregnancy

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Circulatory System at Birth

• Umbilical vein constricts ? prevents blood loss
• Ductus arteriosus constricts ? blood leaving
  right ventricle is sent to lungs
• Blood pressure in left atrium exceeds that in
  right atrium
• Valve closes foramen ovale which fuses within
  atrial wall
• Prevents mixing of de- and oxygenated blood
• Deoxygenated blood in right ventricle is
  oxygenated in lungs
• Replacement of foetal to adult Hb takes 3months
• Each polypeptide/globin chain is coded by a
  separate gene
• Gene for foetal (gamma) globin is suppressed
• Gene for adult (beta) globin becomes active

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Birth

• Foetus lies with its head down against stretched
  cervix
• Weak contraction of uterus every 30min. These
  increase in strength and frequency
• Caused by hormone oxytoccin secreted by posterior
  pituitary gland
• When cervix is fully dilated
• Expulsion of baby by contractions of mother's
  abdominal muscles
• - Umbilical cord shuts down, isolating baby from
  mother
• - CO2 content of the blood rises to stimulate
  baby's first breath
• Expulsion of placenta ? 30min after birth
• - Pregnancy lasts 38 weeks from implantation,
  40 weeks from last period

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Human Growth

• Human growth is spread throughout
• Adult is taller, larger from front to back, has
  larger organs than a child
• Growth permanent increase in amount of organic
  matter
• Produces new cells and increases size of existing
  cells
• Somatotropin (growth hormone) stimulates cell
  division, protein synthesis / released by
  anterior lobe of pituitary gland
• Monitored by standing height and body mass
• Development physical, emotional, mental, social
  changes throughout life

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Human Growth

• Absolute Growth total growth or cumulative
  height of a person
• - at a constant low rate that levels out at 16
  years
• Growth Rate increase in an appropriate feature
  per unit time
• Growth Rate (size at T2 size at T1) / (T2-T1)
  
• Highest in the first year decreases rapidly
  during the first 2 years
• Females and males have similar height until 14
  years when a growth spurt occurs
• - this occurs later but is greater in males than
  in females
• - male becomes taller than the female at 14
  years
• Growth stops by the age of 18 years

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Ageing

• Osteoporosis, loss of calcium from bones, rate of
  cell replacement decreases, less protein made as
  DNA becomes defective
• fall in metabolic rate
• loss of brain cells causes slower responses
  learning ability, loss of memory
• lower rate of nervous conduction reduces reaction
  time
• cartilage on joints ? reduction in ease of
  movement
• arteriosclerosis/atherosclerosis reduce
  efficiency of circulatory system
• reduced vital capacity of lungs ? become more
  breathless on exertion 

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Ageing

• Faulty copying of DNA and a lifetime of exposure
  to mutagens ? faulty proteins may be made
• cross-linking of proteins such as collagen in
  connective tissue, causes connective tissue to
  stiffen e.g. in heart, affecting resting cardiac
  output
• other effect, e.g. wrinkling of skin/reduced
  renal filtration rate/slower circulation of blood
• Bodys immune system produces antibodies against
  its own cells as the immune system deteriorates
  with age. Which also allows abnormal cells to
  proliferatea

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Summary

• Patterns of Behaviour
• Reproductive Behaviour
• Pregnancy
• Human Growth and Development
• Human Populations and Health