Health Psychology Chapter 2 - Systems of the Body

Nervous System

Nervous System communicates via chemical signals called neurotransmitters

1. CNS (Central Nervous System)

   1. brain

   2. spinal cord

2. Peripheral nervous system

   1. somatic nervous system

   2. autonomic nervous system

      1. sympathetic nervous system: “fight or flight”

      2. parasympathetic nervous system: “rest and digest”

CNS (Central Nervous System): Brain

Hindbrain

• medulla: regulates HR (heart rate), BP (blood pressure) and respiration

• pons: controls respiration

• cerebellum: coordinates voluntary muscle movement & maintains balance & equilibrium, muscle tone & posture

Midbrain

• coordination of vidual and auditory reflexes

Forebrain

• cerebral cortex

• hypothalamus

• amygdala

• hippocampus 

Limbic System: Stress & Emotional Responses

• hypothalamus: releases hormones, linked to emotional functioning

• amygdala: general arousal, threat detection

• hippocampus: memory (emotional)

CNS involved in SNS activation

SNS activation triggers release of catecholamines (type of neurotransmitter)

• epinephrine & norepinephrine

orchestrates a host of systemic (stress-like) responses simultaneously

• cardiovascular: increased HR, blood vessel constriction, BP

• Respiratory: increased respiration, airflow into lungs

• Digestive: decreased digestion and urination 

Nervous System: Diseases 

• epilepsy 

• parkinson’s disease

• cerebral palsy

• multiple sclerosis 

• huntington’s disease

• dementia/alzheimer’s disease 

  • amyloid & tau (protein) deposits in the brain

  • cerebrovascular disease

  • sleep (lack of) as sleep removes amyloid

Endocrine System

made up of several glands that secrete hormones into the blood stream to stimulate activity in the organs

1. pituitary glands

   1. and the hypothalamus refulate the endocrine system

2. adrenal glands

   1. made up of the adrenal medulla & adrenal cortex

   2. secrete hormones implicated in stress response

in response to stress, activation of the HPA axis (hypothalamic-pituitary-adrenal-axis)

Endocrine System: Diseases

• diabetes: chronic inability to manufacture or properly use insulin

• Type I Diabetes: autoimmune disorder where the immune system erroneously destroys body’s own cells that are needed to produce insulin 

  • early in life

  • partly genetic

• Type II Diabetes: insuff insulin produced by the body

  • largely lifestyle related

  • typically happens after 40

• comorbid with coronary heart disease & kidney disease

Cardiovascular System

• BP (Blood Pressure)

• PEP (Pre-ejection period)

• CO (Cardiac Output)

• TPR (Total Peripheral Resistance)

BP (Blood Pressure)

force on the blood vessel walls from systolic and diastolic processes

• systole: heart contracts, pump blood out

• diastole: heart relaxes, take in blood 

PEP (Pre-ejection period)

time between left ventricle contraction and aortic valve opening 

• a pure measure of SNS activation

CO (Cardiac Output)

volume of blood pumped per min

• indicator of cardiac functioning

TPR (Total Peripheral Resistance)

vascular resistance to blood flow

• index of “stiffness” in the arteries

Cardiac Efficiency

High cardiac efficiency

• blood pumped quickly (short PEP), in high volumes (high CO) and at low resistance (low TPR)

• physically fit individuals 

Low cardiac efficiency

• blood pumped slowly (low PEP), in low volumes (low CO), at high resistance (high TPR)

• physically unfit individuals 

Heart-Rate-Variability (HRV)

or vagal tone

is the variation in time between heart beats

variability occurs when the vagus nerve exerts control of the heart i.e. PNS activity

Heart Rate: is the no. of heart beats in 1min (norm is 60-100bpm)

in general, higher HRV (vagal tone) is associated with

• better fitness

• better adaptability

• better cognition

• better general health

• lower SNS activation in response to stimuli/stressor

• higher HRV “car accelerator & brake”: PNS activity is akin to applying a brake to reduce SNS activity. this balancing contributes to inter-beat variability. the amount of such variability is HRV. high HRV indicates body’s ability to continuously balance itself in response to any stimuli.