Biological Rhythms - Intro, Ultradian and Infradian Rhythms

Question 1

What is a biological rhythm?

Answer 1

• biological rhythms have an important influence on the way in which body systems behave
• controlled by an int body clock called endogenous pacemakers
• influenced by ext changes in env called exogenous zeitgebers

Question 2

What are all three biological rhythms and what are the differences?

Answer 2

• ultradian rhythm cycle lasts less than 24 h e.g. stages of sleep each approx 90 mins
• circadian rhythm cycle lasts for 24 hours e.g. sleep wake cycle
• infradian rhythm cycle lasts for longer than 24 hours e.g. female menstrual cycle approx 28 days

Question 3

What is meant by an ultradian rhythm and give an example?

Answer 3

• UR is a bio rhythm that lasts for less than 24 hours
• one type of UR are the stages of sleep, each of the 5 stages lasting approx 90 mins and alternating bw REM and NREM e.g.
• it is known as the sleep staircase as a person can exp upto 5 cycles per night that repeat in a rhythmic pattern

Question 4

What is the intro for the research into ultradian rhythms

Answer 4

• research into UR using an EEG has shown there are 5 stages to sleep, each characterised by difference in brain, muscle and eye activity
• there is stage 1 and 2 light NREM sleep, stage 3 and 4 deep NREM sleep and stage 5 REM sleep

Question 5

Describe stage 1 and 2 sleep

Answer 5

• light and NREM sleep where a person can be easily woken
• both experience alpha waves
• however in stage 2 there are occasional random changes in pattern called sleep spindles
• these are high frequency k - complexes that protect brain from awakening

Question 6

Describe stage 3 and 4 sleep

Answer 6

• deep and NREM sleep where it is difficult to wake someone
• experience delta waves with lower frequency and higher amplitude

Question 7

Describe stage 5 sleep

Answer 7

• brain experiences theta waves
• eyes occasionally move around so REM sleep
• body is paralysed
• however the brain activity is similar to an awake brain
• dreams are often experienced in this stage

Question 8

What are the three AO3 points to evaluate ultradian rhythms?

Answer 8

Strength - prac apps
Strength - scientific methods
Weakness - low eco val

Question 9

What is meant by infradian rhythms and give an example

Answer 9

• IR are bio rhythms that last longer than 24 hours
• they are influenced by endogenous and exogenous factors
• one example is the female menstrual cycle which is an endogenous system that lasts bw 28 - 35 days

Question 10

Describe the process of the example of an IR - the menstrual cycle

Answer 10

• begins on 1st day of period when womb lining is shed and lasts till day before next period
• pituitary gland in brain releases FSH
• activating release of oestrogen from ovaries, causing an egg to mature
• inc of oestrogen inc levels of LH from pituitary gland, egg released
• oestrogen develops lining of womb, progesterone thickens lining, readying for preg
• if preg doesnt occur, egg is absorbed into body and womb lining comes away, leaves body
• cycle begins again
• menstrual cycle can be affected by exogenous factors like stress and pheromones

Question 11

What are the three AO3 points to evaluate infradian rhythms?

Answer 11

RTC by Russell
Discussion - low control over extraneous variables
Strength - synchronise