Biopsychology - rhythms Flashcards
What is a circadian rhythm?
A biological rhythm that repeats approximately once every 24 hours.
What is an Infradian rhythm?
biological rhythm that repeats less frequently than once every 24 hours (e.g. once a week/month).
What is an Ultradian rhythm?
Biological rhythm that repeats more frequently that once every 24 hours.
Examples of Infradian rhythms
-Menstrual cycle - a month
-SAD - seasonal affective disorder - takes a year - mood lowers in winter, improves in summer.
What is the menstrual cycle?
-28 day fertility cycle - 6 day period.
-Affected by oestrogen pre-ovulation and progestorone post-ovulation.
Research Evaluation for the Infradian cycle - McClintok.
1970
-135 women lived in same uni dorm, recorder period onset and duration.
-Results showed women appeared to synchronize cycle with friend groups.
-Supported by similar findings from Rusell 1980.
Research Evaluation for the Infradian cycle - Stern and McClintok
1998
-Investigated whether synchronization due to sharing hormones.
-20 women - pas to wipe on lip everyday.
-Pads taken from armpits of 9 donors.
-women shorten or extent menstrual cycle to match donor.
-suggests synchronization due to pheromones acting as a exogenous zeitgeber.
Evaluation of pheromones
pheromones as a chemical messenger are not accepted widely as a process that happens in humans.
Evaluation of sync of menstrual cycle
+McClintok (1971) Has been replicated (Russel 1971) with positive results.
-However, number of replications show no sync, e.g. one on cohabiting lesbian couples did not sync (Trevathan 1993), which are optimum conditions for for sync.
-Menstraul cycle can vary in length, women may appear to sync due to the variability of their cycles - not taken into consideration in all the studies showing positive results.
+Evolutionary theories suggest synchronization is advantageous - stop one male dominating whole group and impregnating all female - leading to genetic diversity in small human groups.
-However, synchronization may be maladaptive due to making women all compete with other women to be fertilized by the best genes.
Key features of the nervous system?
-specialised network of cells - primary communication system.
-electrical and chemical signals.
-2 main functions:
-collect, process and respond to info from environment.
-co-ordinate working of different organs and cells in body.
structure and function of CNS?
-Brain and Spinal Cord.
-centre of conscious awareness.
-cerebral cortex - highly developed in humans - higher mental functions.
-brain divided into 2 hemispheres.
-Spinal cord - extension of brain - responsible for reflex actions.
-Passes messages to and from brain - connects nerves to PNS.
Structure and Function of peripheral nervous system?
-transmits messages - via millions of neurons - to and from nervous system.
-PNS subdivides in to Automatic nervous system (ANS) and Somatic Nervous System (SNS).
Function of ANS?
-Automatic nervous system
-vital functions in the body: breathing, heart rate, digestion, sexual arousal and stress response.
Function of SNS?
-Somatic nervous system
-governs muscle movement - receives information from sensory receptors.
