Mechanism

• Attachment is a strong reciprocal emotional bond between an infant and a primary caregiver

  
• Schaffer and Emerson's 1964 study on attachment:

  • Aim: identify stages of attachment / find a pattern in the development of an attachment between infants and parents
  • Participants: 60 babies from Glasgow
  • Procedure: analysed interactions between infants and carers
  • Findings: babies of parents/carers with 'sensitive responsiveness' were more likely to have formed an attachment
• Freud's superego is the moral component of the psyche, representing internalized societal values and standards
• The circulatory system diagram shows the flow of blood from the heart to the body and back again

  
• The heart is a muscular organ that pumps blood through the body

  
• The aorta is the largest artery in the body, carrying blood away from the heart

  
• The vena cava is the largest vein in the body, carrying blood back to the heart

  
• Capillaries are tiny blood vessels allowing oxygen and nutrients to pass from the blood to the cells

  
• Arterioles are small arteries carrying blood from the capillaries to the larger arteries

  
• Venules are small veins carrying blood from the capillaries to the larger veins

  
• Cardiac muscle contractility describes the relative ability of the heart to eject a stroke volume
• Stroke volume refers to the amount of blood pumped per contraction or per beat
• Characteristics of cardiac muscle tissue cells:

  • Involuntary
  • Striated
  • Intrinsically controlled
  • Branched with single-centered nuclei
  • Abundant mitochondria
• Cardiac muscle cells are specialized to pump blood powerfully and efficiently throughout our entire lifetime
• Cardiac muscle cells are responsible for electrical stimulation leading to mechanical function
• Cardiac muscle mechanics:

  • Isometric Contraction: muscle contraction without significant shortening or change in distance
  • Isotonic Contraction: muscle contraction without significant change in force of contraction
• The cardiac cycle (Heart beat) has two isometric phases (Isovolumic contraction and Isovolumic relaxation) and other isotonic phases
• The aorta is the largest artery in the body, carrying blood away from the heart to the rest of the body

  
• Capillaries are tiny blood vessels that allow oxygen and nutrients to pass from the blood to the cells of the body

  
• Arterioles are small arteries that carry blood from the capillaries to the larger arteries

  
• Venules are small veins that carry blood from the capillaries to the larger veins

  
• A sarcomere is the smallest unit of a myofibril

  
• The illustration shows the structure of a skeletal muscle

  
• Cardiac muscle tissue

  
• The image shows the electrical system of the heart

  
• The diagram of the human heart includes labels for the heart's chambers, valves, and major blood vessels

  
• Action potential in cardiac muscles has the following characteristics:

  • Long duration
  • Stable resting membrane potential
  • Plateau phase
  • Auto-rhythmicity
• The action potential in cardiac muscles is initiated by the influx of sodium ions (Na+), causing rapid depolarization
• The plateau phase in cardiac muscle is critical as it:

  • Causes ventricular contraction to last much longer than in skeletal muscle
  • Prevents additional impulses from spreading through the heart prematurely, allowing effective blood pumping
• Excitation of the heart is triggered by an electrical impulse rather than neurotransmitters
• Contraction of the heart is triggered and regulated by the elevation of intracellular calcium influx
• Cardiac muscle fibers contract via excitation-contraction coupling, using a mechanism called calcium-induced calcium release (CICR)
• Excitation-contraction coupling involves the conduction of calcium ions into the cardiomyocyte, triggering further release of ions into the cytoplasm
• During relaxation, calcium is re-accumulated in the sarcoplasmic reticulum by Ca+2 ATPase (SERCA)
• The importance of Ca+2 from T tubules in cardiac muscle contraction is crucial for maintaining strength due to the limited Ca+2 storage in the sarcoplasmic reticulum
• Summary of Excitation-Contraction Coupling:

  • Ca+2 enters the cell during depolarization and triggers release of Ca+2 by terminal cisternae
  • Ca+2 binds to TN-C, inducing a conformational change in the troponin complex
  • Myosin heads bind to actin, leading to cross-bridge movement and reduction in sarcomere length
  • Ca+2 is re-sequestered by the sarcoplasmic reticulum by the SERCA pump
  • Ca+2 is removed from TN-C, allowing the sarcomere to relax
• An illustration of the structure of a skeletal muscle

  
• A diagram of the human heart, with labels indicating the names of the heart's chambers, valves, and major blood vessels

  
• The image also includes a brief description of the heart's function
• Cardiac muscle tissue is the type of muscle found in the heart