EXAM FOCUS Biological Rhythms

Connect

What questions do

you think might come up on what

we have studied so

far?

Objectives

Today you will Consider types of exam questions Consider material you could use to answer

these questions Consider requirements of these questions

So that you can Plan and produce answers to cover the

possible exam questions at least to your target grade standard

June 12

Outline one or more examples of ultradian rhythms. (4 marks)

(This should be about a 100 word answer – no AO2 needed)

January 11

Discuss the role of endogenous pacemakers in the control of one or more biological rhythms. (9 marks + 16 marks)

(This is just like the newer 24 mark essays. It should be around 200 words of AO1 – and 8 MRI points including at least 1 IDA)

What else could you get?

Outline one or more examples of infradian/circadian rhythms (4 marks)

Describe and evaluate research on circadian rhythms (8+16 marks)

Describe and evaluate research on infradian and ultradian rhythms (8+16 marks)

This question could be split into two lots of (4+8 marks)

The importance of IDA

If you look at the mark scheme for this unit, you will see that without using IDA at least once in your essays (12 or 24 markers) you cannot reach the top band for AO2.

This means that you would be losing at least 4 marks (This could be a whole grade!)

But what could you include?

A2 Psychology: IDA Superheroes ISSUES

The Animal Ace Master Ethnocentric

Gender Bias Beauty

The Ethics Kid

Questioning the usefulness of animal research. Can animal behaviour be applied to humans?Kitty says no!

Passionate that theories are prone to culture bias, The Master of Ethnocentrism would die to prove that theories which are Ethnocentric cannot be applied to all cultures.

Ironically, the Gender Bias Beauty wants equal application of theories to both Genders. Her pet hate is when theories or studies can only be generalised to one gender or only explain behaviour in just men or just women.

Can a theory or study be criticised on the grounds of ethics? Is it unethical? The Ethics Kid is here to find out!

A2 Psychology: IDA Superheroes DEBATES

Nature-Man

Super-Nurture-al.

Free Will-i-am

Doctor Determinism

The Reductionist-er!

Fighting for all things natural. I believe that all behaviour is pre-determined by biological factors: hormones, genes & evolution.

Doctor Determinism knows that all behaviour is determined by forces beyond human control.

Determined to prove that behaviour is learned and influenced by social forces. I hunt down Nature-Man for the ultimate of battles: The Nature-Nurture Face Off. Fighting against

the evil threat of Determinism, Free Will-i-am believes that we have the power to control our own behaviour. It’s all about the choice

Flying through the skies on a mission to show that psychologists reduce complex behaviour down to over-simplified factors. He believes that behaviour should be looked at holistically.

A2 Psychology: IDA Superheroes APPROACHES

Pavlov’s Power Puppy

In the name of Behaviourism, Pavlov’s Power Puppy is here to show that all behaviour can be learned. Just ring that bell and I’ll be there ready to help!

The Freud-ster

In the name of the Psychodynamic approach…Motivated by his unconscious sexual desire, The Freud-ster wants to prove that our behaviour really is only the tip of the iceberg!

Darwin’s DoubleIn the name of Evolution, this Double Act are here to show that humans really did evolve from Apes! It’s all about the genes!

In the name of Biology, Tommy Testosterone fights to prove that behaviour is underpinned by biological factors: brain structure, neurochemicals and genetics.

Tommy Testosterone

The Memory Marvel In the name of Cognitive Psychology, the Memory Marvel just goes to show that behaviour can be underpinned by cognitive processes. It’s all in the thinking!

What do you need to be able to do?

Write a description of circadian rhythms in about 100 words (4 marks) and 200 words (8 marks)

Identify 8 criticisms of this including one IDA topic (MRI – around 50 words each)

Write a description of ultradian and infradian rhythms in about 100 words each

Identify 4 criticisms of each of these including IDA (MRI)

Circadian RhythmsAO1 AO2 IDA

Sleep-wake Cycle• Circadian = 24 hours• Cycle persists despite

isolation from light

• Particpants not isolated from light in early research

• Demonstrated by Siffre and Aschoff & Wever

• External cues important too (Folkard at al)

• Cycle length varies in individuals

Biological approach – suggests bodily rhythms can be explained by biological factors

Deterministic – ignores the element of choice/free will humans have over their behaviour Core body temperature

• Lowest at 04.30; highest at 18.00

• Post-lunch dip, even without food

• Linked to cognitive abilities (Folkard et al)

• Evidence that change is caused by temp (Giesbrecht at al)

• Other research suggests link is spurious

Hormones• Cortisol lowest at

midnight• Melatonin and growth

hormone highest at midnight.

Ultradian and Infradian RhythmsAO1 AO2 IDA

Ultradian• Less than one day• Sleep stages = 1st

4 – NREM, 5th – REM• BRAC = 90 mins

within 24 hour rhythm

• REM does not equal dreaming

• BRAC important because it ensures biological processes work in unison

Determinist (e.g. PM) but can change through willpower (Born et al)

Real-world application - phototherapy

Infradian• Female menstrual

cycle regulates ovulation

• Male shave 20 day cycle of body temp and alertness

• SAD caused by melatonin during winter months

• Menstrual cycle also subject to exogenous cues

• Some women suffer PMS

• SAD could also be consequence of disrupted circadian rhythms

Preparation – working together In our next lesson, you will

be writing two essays.

1. Describe and Evaluate research on circadian rhythms (8+16)

2. Describe and evaluate research on ultradian and infradian rhythms. (8+16)

ESSAY WRITING

Questions for today (25 mins each!)

1. Describe and Evaluate research on circadian rhythms (8+16)

2. Describe and evaluate research on ultradian and infradian rhythms. (8+16)

ENDOGENOUS PACEMAKERS / EXOGENOUS ZEITGEBERS

Connect

What might influence our natural rhythms?

Make a list of as many things you can think of and try to categorise them into internal (endogenous) and external (exogenous)

Objectives

Today you will Learn about endogenous pacemakers Learn about exogenous zeitgebers Consider the implications of research done in this

area

So that you can Describe the role of endogenous pacemakers in

biological rhythms Describe the role of exogenous zeitgebers in

biological rhythms Evaluate the role of Eps/Ez’s in biological rhythms

Where is the body clock?

Light travels from retina (back of the eye) along the optic nerve, and is picked up by the SCN

The ticking of the biological clock The basis of circadian rhythm lies in interactions between

certain proteins creating the ‘tick’ of the biological clock

It is an ingenious negative feedback loop

Darlington et al (1998) first discovered it in fruit flies but actual proteins vary from species to species

The protein mechanism is present in SCN (central oscillator) and other cells throughout the body (peripheral oscillators)

This explains why different functions have different rhythms

Body clock negative feedback loop

CLK + BMAL1

PER CRY

PER + CRY

First two

decrease

This makes second

two decrease also

In the morning two

proteins bind

This stimulates production two new proteins

These new proteins

deactivate the first two

CLOCK and BMAL1 begin to decrease

As CLK and BMAL1

decrease, production of PER and CRY

decreases also

24 hour period

Eps: The suprachiasmatic nucleus (SCN)

Tiny cluster of cells, in the hypothalamus, just above optic chiasm

Obtains info about light via optic nerve

If the sun rises earlier than day before, light resets the clock

There is one in each hemisphere, divided into two parts, dorsal and ventral.

Ventral is reset much more quickly, dorsal more resistant to being reset as it is less affected by light (Albus et al, 2005)

Eps: Pineal gland and melatonin SCN sends signals to pineal gland telling it to

increase melatonin at night

Melatonin induces sleep by inhibiting brain mechanisms responsible for alertness

In birds and reptiles this is just below the thin skull bone and so directly affected by light – light inhibts melatonin production.

Some lizards have a third ‘eye’ which sticks out of a small opening in the skull and receives info about light

Pineal eye of a Green Anole Lizard

Activity

Read over and complete the exercises on endogenous pacemakers in your booklet

Ezs: Resetting the biological clock This process of resetting the biological

clock is known as ENTRAINMENT.

The opposite of this is FREE-RUNNING

This is where the biological clock runs without any exogenous cues.

Ezs: Light

Dominant zeitgeber in humans

Light can reset the main pacemaker (SCN)

It can also reset other oscillators because the protein CRY (chryoptochrome) is light sensitive

This may explain why Campbell and Murphy (1998) found that if you shine a light on the back of participants knees, it shifts their circadian rhythms

Ezs: Social cues

Until recently it was thought these were the main EZ’s – we eat, go to bed, get up etc at socially determined times

It seemed our bodily rhythms were entrained by social convention, not internal biology.

Today we know light is the dominant EZ, and we also know that all parts of the body produce their own oscillating rhythms.

E.G. zeitgebers for heart and liver appear to be reset by eating, so light is not their primary zeitgeber. (Davidson, 2006)

Ezs: Temperature

Cold blooded animals have their circadian rhythms modified by external temperature

Buhr et al (2010) Humans and other warm blooded

animals’ body temperature cycle is governed by the circadian clock, and these temperature changes entrain other circadian rhythms.

Activity

Read over and complete the activities in your booklet on exogenous zeitgebers

Review Showdown

Where is the SCN? What is its function? Describe how the body clock works? What other examples are there of endogenous

pacemakers? What three examples of exogenous zeitgebers

have you learned? One study that supports the influence of zeitgebers One study that supports the influence of

pacemakers One IDA issue that can be applied to this topic

Homework

For next week (TUESDAY!)

Discuss the role of endogenous pacemakers and exogenous zeitgebers in circadian rhythms (8+16)

There are some documents on Moodle to help you with this.

Endogenous Pacemakers and Exogenous ZeitgebersAO1 AO2 IDA

Endogenous Pacemakers• SCN – main EP• SCN contains

protein mechanism• Pineal gland

controls melatonin secretion

• SCN evidence – ‘mutant’ hamsters

• Desynchronisation leads to symptoms similar to jet lag

Evolutionary approach – SCN lesions in chipmunks (deCoursey et al)

Non-human animal studies evaluated in terms of ethics and relevance.Exogenous Zeitgebers

• Light is dominant zeitgeber

• Social cues also important

• Biological rhythms can be entrained by temperature

• Artifical lighting may also reset biological clock

• Failure of biological clock leads to sleep-phase disorders

• Biological clock is really a blend of endogenous and exogenous factors

You could also use studies

from rhythms topics to add to

your AO2:You just need to make sure you say why they are relevant!