lecture 6 Flashcards
what is the immune system?
it is the bodies defence system to distinguish and process foreign and self-threats
the immune system responds to antigens. what are antigens? examples
antigens are any molecule that can stimulate an immune response i.e. microbes (bacteria, viruses), smoke, pollen, etc
is exercise an antigen?
yes, because it produces some damage in the muscle and then you get an immune response.
not all immune responses are bad
what are the three lines of defence in the immune system?
1st line - physical & (bio) chemical barriers - skin, earwax, stomach acid
2nd line - innate (non specific) immune response - quick response
3rd line - adaptive (specific) immune response - slower, memory for future responses
- T and B lymphocytes
what lymphocytes are apart of the adaptive immune system
T and B lymphocyte cells
when does the immune system develop?
the innate immune system is present in the body at week 4
functional T cells develop at week 16 of pregnancy
what happens to the foetus immune system at birth?
the innate immune system is muted at birth otherwise it would recognise the maternal cells as antigens and then attack them.
what happens in the childhood immunity?
- immune system matures
- maternal antibodies mirror the immunity of the mother
- continually make immune system stronger throughout growth (the more you are exposed)
what happens with the immune system in the aged?
- immune system declines in the ages
- Lower number of naive T and B cells = decreased ability to respond to new diseases
- innate immune system show decrease phagocytic ability
why is childhood immunity important?
important for early protection against infectious disease over the first 6 months of life
when is the greatest risk of death from infection?
very early in life and later in life (newborn & elderly)
what is the endocrine system?
it is the system that secretes hormones
what are hormones ?
are the chemical messengers which are released into the body by your endocrine glands
where do hormones go?
they either reach a target tissue directly or pass into cell to nucleus
what are the two different types of hormones? examples also
Amino acid hormones - cannot cross membrane
eg. epinephrine, glucagon, thyroxine
lipid derived hormones - its a lipid soluble so can cross membrane
eg. steroid hormones, estrogen, testosterone
what is the major endocrine gland?
the Hypothalamus
what does the growth hormone do?
growth of connective tissue, bone growth and muscle hypertrophy
what are the three actions of hormones?
- morphogenesis - regulate physical growth and maturation of individuals
- integration - integrate activities of the body in response to internal and external stimuli
- Maintenance - act to maintain the internal environment of the body
what does Morphogenesis do?
regulate physical growth and maturation of individuals
e.g. Growth hormone (GH)
what happens when the Hypothalamus secretes GRGH (growth hormone releasing hormone)??
this stimulates GH release from pituitary gland, which stimulates liver to secrete insulin-like growth factor (IGF) hormones
What is IGF-1 and what does it do
IGF-1 - a insulin like growth factor which is a potent stimulator of rapid production of cartilage cells at epiphyseal plate
what hormones do we need for linear growth to occur in children?
IGF-1 (insulin like growth factor) , GH (growth hormone), TH (thyroid hormone)
what does growth hormone do in adults?
- stimulates protein synthesis in muscle and the release of fatty acids from adipose tissue (anabolic effect)
- used in the synthesis of proteins
when does growth hormone usually happen? what happens if you stay awake all night consistently?
growth hormone is usually secreted when asleep. therefore if always awake you may be stunted in growth
what are the sex steroids which are most commonly studies in growing children
testosterone and estradiol
what is the second hormonal action??
Integration - through circulation to most parts of the body, integrate activities of the body in response to internal and external stimuli
e.g. adrenaline/epinephrine
What is the third hormone action? examples
Maintenance - act to maintain the internal environment of the body (homeostasis)
e.g. insulin, glucagon, ADH, Calcitonin aldosterone
what does insulin do?
it is secreted by pancreas - it increases glucose uptake from blood and glycogen storage
- necessary for full expression of GH effects
what happens to the thyroid when ageing?
- thyroid often becomes lumpy (nodular).
- metabolic rate gradually declines, beginning at age 20
why is normal thyroid function necessary?
- for normal physiological growth and maturation
- GH can not produce its normal effects without thyroxine
- thyroid hormones accelerate most processes
what are the endocrine changes with ageing ??
the endocrine system shows relatively few functional changes with age. with the most dramatic exception is the decline in the concentration of reproductive hormones
what is menopause? how does it occur
due to ageing ^
menopause is when a womens ovaries stops releasing eggs. this is due to a decrease of the female hormones estrogen and progesterone = menstrual activity decreases and eventually ceases
what are the changes in the male reproductive system due to ageing?
decrease sperm production
decrease erectile disfunction
