Vasodilation and Blood Flow Dynamics

Lab Study Guide for Exam 1 (Labs 1-4)

Lab 1

Learning Objectives

• Homeostasis is the process by which living organisms maintain stable internal conditions despite external changes
• Homeostasis regulates factors like temperature and pH
• Negative feedback is a control mechanism in biological systems where a change triggers a response counteracting the change to maintain homeostasis
• Set-point is the ideal value or range for a physiological variable, such as a human body temperature around 37°C
• Vasoconstriction is the narrowing of blood vessels, increasing blood pressure and reducing flow to certain areas in response to cold or stress
• Vasodilation is the widening of blood vessels, decreasing blood pressure and increasing blood flow in response to heat or metabolic activity
• Local blood flow is the distribution of blood to specific tissues or organs based on metabolic needs
• Local blood flow is increased to the muscles during exercise
• Blood pressure is the force exerted by circulation on blood vessel walls, measured in mmHg as systolic over diastolic pressure
• Hypotension is abnormally low blood pressure, indicated by readings below 90/60 mmHg, potentially causing dizziness, fainting, or shock
• Hypertension is abnormally high blood pressure, indicated by readings above 130/80 mmHg, increasing the risk of heart disease and stroke
• A plethysmograph is a tool used to measure changes in volume within an organ or the body to assess blood flow
• Thermoreceptors are sensory receptors detecting temperature changes, playing a crucial role in thermoregulation
• The peripheral blood flow from the left ventricle to the fingertips:
• Blood pumps from the left ventricle into the aorta.
• The aorta, the largest artery, branches into smaller arteries.
• Blood flows into the subclavian artery, supplying the arms.
• The subclavian artery becomes the brachial artery as it travels down the arm.
• The brachial artery splits into the radial and ulnar arteries, supplying the forearm and hand.
• These arteries branch into the digital arteries, supplying blood to the fingertips.
• The return path to the left ventricle:
• Blood returns from the fingertips through the digital veins.
• The digital veins merge into the ulnar and radial veins.
• The ulnar and radial veins combine to form the brachial vein.
• The brachial vein drains into the subclavian vein.
• The subclavian vein joins the internal jugular vein to form the brachiocephalic vein.
• The brachiocephalic veins merge into the superior vena cava.
• Blood enters the right atrium of the heart.
• Blood flows from the right atrium to the right ventricle.
• Blood is pumped from the right ventricle into the pulmonary arteries for oxygenation.
• Oxygenated blood returns to the left atrium via the pulmonary veins.
• Blood flows from the left atrium to the left ventricle, completing the circuit.

Changes in Pulse Amplitude and Peripheral Blood Flow

• Pulse amplitude is the strength or intensity of the pulse in the arteries, influenced by blood volume
• During vasodilation, blood flow to the periphery increases, increasing the pulse amplitude
• Pulse amplitude can be felt more distinctly when vasodilation occurs
• During vasoconstriction, blood flow to the periphery decreases, lowering the pulse amplitude
• Pulse amplitude may be harder to detect during vasoconstriction
• Heat causes vasodilation, increasing blood flow and pulse amplitude
• Cold causes vasoconstriction, decreasing blood flow and pulse amplitude
• During physical activity, vasodilation occurs in active muscles, increasing blood flow and pulse amplitude
• Hormones like adrenaline can cause vasodilation or vasoconstriction, affecting blood flow and pulse amplitude
• The sympathetic nervous system induces vasoconstriction, reducing pulse amplitude, while the parasympathetic system promotes vasodilation, increasing pulse amplitude
• Strong pulse indicates good peripheral circulation and vasodilation
• Weak pulse suggests poor circulation, vasoconstriction, or cardiovascular issues
• Lower pulse amplitude indicates reduced blood flow
• Effects of vasoconstriction on peripheral blood flow include reduced flow, increased blood pressure and conserved heat
• Nutrient delivery is reduced and peripheral blood flow is increased
• Effects of vasodilation on peripheral blood flow
• Peripheral blood flow increases
• Resistance decreases
• A blood pressure lowers while heat loss promotes.
• Oxygen delivery improves and nutrient delivery is enhanced

Blood Flow Path

• Blood flows from the left ventricle into the aorta
• Blood enters the ascending aorta then passes through the aortic arch
• The ascending aorta then distributes to the upper body and arms via the subclavian artery
• The subclavian artery continues as the axillary artery in the armpit
• The axillary artery becomes the brachial artery, which runs down the arm
• The brachial artery divides into the radial artery (lateral) and ulnar artery (medial) in the forearm
• These arteries divide into palmar arches, which then branch off into digital arteries to the fingertips
• Veins return to the heart via the digital veins, draining into palmar venous arches
• These lead to the radial and ulnar veins, merging into the brachial vein in the upper arm
• The brachial vein becomes the axillary vein as it enters the shoulder
• The axillary vein becomes the subclavian vein, carrying blood towards the heart
• Joined by the internal jugular vein, it forms the brachiocephalic vein
• The brachiocephalic veins merge into the superior vena cava, which carries blood to the right atrium
• Blood flows through the tricuspid valve into the right ventricle
• Blood is then pumped through the pulmonary valve into the pulmonary arteries to go to the lungs
• Oxygen-rich blood returns to the left atrium via the pulmonary veins
• Blood flows through the mitral valve into the left ventricle, completing the circuit

Vasodilation Effects

Effects on downstream(peripheral) vessels: Increased Blood Flow: Vasodilation reduces resistance in blood vessels Blood Flow to Tissues: Crucial for delivering oxygen and nutrients especially in exercise

Effects on upstream/central vessels:

• Decreased Resistance: There is decreased resistance in the less diluted segment of the vessel,

• Upstream Flow: Blood flow may increase toward site

• Downstream tissue cells and capillary beds see a decrease in blood pressure overall

• May increase central pressure due to volume increase

• Gravity affects the lower limbs: the hydrostatic pressure will be greater because the blood in the arterial and venous supply is acted upon by gravity

• Standing still causes pooling in the legs, causing fainting

• Because the heart has to pump blood upward, blood presssure will be generally the same for the head

• Minimal Gravity Impact on Sharks: Sharks, with their horizontal orientation, experience a more even distribution of blood pressure, similar to aquatic environments' reduced gravitational effects.

• Giraffes must be especially careful: To stand upright, they require a ton more blood pressure, blood can pool in extremeties

Lab 2

Key Terms

• Central Nervous System (CNS): The brain and spinal cord, processes sensory information, sends commands, integrates input, and coordinates responses.
• Afferent Neuron: Carries sensory information from receptors in the body toward the CNS.
• Sensory Neuron: A type of afferent neuron that carries information from sensory receptors to the CNS.
• Efferent Neuron: Carries commands or signals away from the CNS to effector organs.
• Motor Neuron: A type of efferent neuron that carries impulses from the CNS to muscles, controlling voluntary and reflexive actions.
• Interneuron: Connects afferent and efferent neurons within the CNS, aiding complex functions.
• Reflex Arc: A neural pathway controlling involuntary response to a stimulus, involving sensory, inter, and motor neurons.
• Visuomotor Learning: Learning to coordinate visual information with motor actions.
• Sensorimotor Adaptation: Adjusting motor actions in response to changes in sensory input.
• Prismatic Adaptation: A specific form of sensorimotor adaptation when prisms distort visual input and alter motor commands.

Ascending Visual Pathway (Visual System)

• Retina: The visual pathway begins from the retina here a layer of light-sensitive cells (rods and cones)
• Optic Nerve: Electrical Signals travel this nerve, here visual information is carried to brain
• Optic Chiasm: Nerve fibers from here is able to to cross to the opposite side of the brain
• Optic Tract: From here, visual information is sent to optic tract which then leads to the thalamus
• Lateral Geniculate Nucleus (LGN): From this centre for information, signals are sent to visual cortex
• Optic Radiations: Where visual information travels from primary visual cortex
• Visual Cortex (V1): Where orientation is processed

Ascending Auditory Pathway (Auditory System)

• Cochlea: Sound waves are converted into hair cell electrical signals.
• Auditory Nerve (Cochlear Nerve): These signals transmit towards the brainstem
• Cochlear Nuclei: Auditory Fibers synapse in brainstem nuclei
• Superior Olivary Complex: Receives auditory signals to play a role in localiziing sounds
• Lateral Lemniscus: Auditory information ascends toward midbrain
• Inferior Colliculus: Auditory information is processed to localize sound
• Medial Geniculate Nucleus (MGN): Here auditory signals are relayed -Auditory Cortex: This is where information travels from temporal lobe, loudness, frequencies can be found here

Descending Motor Pathway (Motor System)

• Motor Cortex: The primary source of motor command, responsible for planning
• Internal Capsule: Signals decend through a bundle of fibre connecting the brain to the spinal cord
• Brainstem (Medulla): Fibres from the corticospinal tract is responsible for crossing, mainly responsible for limb movement control Anterior Corticospinal Tract: Responsible for trunk musclecontrol
• Spinal Cord: Descending fibres synapse from motor neuron Lower Motor Neurons: Neurons project to skeletal muscles controlling movement
• Ascending visual pathways: involve retina, opic nerve, cortex
• Descending motor pathway: is made of the motor cortex, and decussates to lower the neurons

Auditory VS Visual Cues

• Responses are faster to Auditory Cues than Visual Cues

• Auditory Processing: Because they auditory pathway has faster signals being delivered-

• Visual Cortex: Because light travels by optic chiasm and Lateral something

• Simpler Neural Pathways: Cues are shorter, introduce slight delay in processing time

Sensory Receptor Functions

• Sound Waves are received almost instantaneously
• Sound processing has attention, but is more effective at grabbing
• Humans require directed action otherwise more attention is on visual stimulation
• Speed of Sensory Processing: Faster because of neural pathways Number of Synapses: Lower as sensory receptors adapt very well due to short processing time

Neurophysiology of Prematic Adaptation

• When focus is applied the retina will have signals through photons which can be transmitted by the cortex
• Over time perception allows adaptation to occur
• Brain will initially see something wrong eventually it will receive that information and adjust accordingly to compensate
• There is a benefit from being adaptable, especially so you can learn and recover from injuries

Anatomy of the Auditory Pathway:

• Outer Ear: Where the pinna and canal directs soundwaves
• Middle Ear: Where vibrations are converted to mechanical
• Tympanic Membrance (Eardrum): Where vibrations increase
• Ossicles: To transport the the inner ear Inner Ear: A spiral fluid field structure to conduct sensory information for hearing
• Haicells: Located near the cochlea used for converting into electrical energy
• Basilar Membrance: Vibrates in response to sound frequencies Anditory Nerve (Cochlear Nerve): Relaying signals to the brain Brainstem: Processes auditory information

Anatomy of the Visual Pathway

Retina: Located at the back of the eye- Photoreceptors: Rods and cones where light is converted to neural Bipolar Cells: Synapse from photoreseptors to relay process Ganglion Cells: Where neurons send signals from visual stimmulus Optic Nerve: Carries information from retina to brain Optic Chiasm: Optic nerves partially cross for visual info to transmit Lateral Geniculate Nucleus (LGN): Helps interpret light info

Sensorymotor Adaptation

• Maintains coordination/balance which is essentially for learning motor skills -Adaption has several clinical application depending by adapting to stroke patients visual Ex: Wearing corrective leases

Lab 3

• Mechanoreceptor are useful for distortion
• Propioceptors are used for body position, movement etc. in muscles, tendons, joint
• Chordotonal Organ: Is sensitive to vibration, sound and movement
• Stretch Receptor: Response to stretch, regulates muscle contraction
• Nerve: bundle of axons that transmit electrical signals
• Afferent : Carry sensory information from peripheral sensory

Anatomy of the Chordotonal Organ

• Chordotonal Organ is found typically in the abdomen legs Structure: Sensory Neurons: Detects mechanical stimuli Each chordontonal is has scolopidia Function
• Detects change in body position Types Chordotonal Organ Campaiform sensilla: changes skeletal tension

Coordinating Leg Movements

Chordotonal- Organ is for helping insects adapt to their enviornments by detecting mechanical changes in movement with neurons. The similar counter part to other organisms are Stretch receptors , helps maintain balance while providing feedback

Information ENcoding Neurons provide info through frequency Temporal Summonation :Where multiple functions have many process allowing to send strong message Neuronal Intergration: Its a part of the circuit where the information is used from frequency to reach threshhold

Senory Adaptation : The process where sensory adapt with time The focus here is the important stimuli -Animals conserve energy Adaptation allows stimuli to be more responsive

Major Type of Stretch Receptors Muscles Muslcus Spindlees are mainly in skeletal systems with the Function of providing muscle feedback to control Golgi tendon prevent the tension in muscle for muscle integrity

Experiments

• Sensory Adaption: Temperature Adaptation

• The chordontal detects movement provides feedback for position Integrates the nervous system, to help animals adapt to their inviromnemts.

• Adaptation also contributes to quick reflexes making them adapt to their invironmne

Lab 4

Learning Objectives: Conduction velocity: The time it takes for impulses to travel

Synaptic Transmission TIme terms:

• Tendon, Muscle bundle, muscle fiber etc.
• Muscles provide mechanical forces for locomotion Neuronal: is located at the end which transmits signals to muscle fibres which help create movement

Function Unit: Is composed for singular neurons working together

• A singular brief contraction is an instance of a twitch
• Tetanus: Is a high continuous contraction
• Motor Unit Recruitment: High rates of muscular force
• Spinal Reflex Arc: Nueronal Pathway for quick reception
• Extensor muscle: For straightness

The interpretation of and electromygram

Baseline Activity: A flat line with minimal electrical activity. Action potentional: Represents muscle Contraction Amplitute: Strength in musclar concentration Frequency: Suggest rates in muscle activation

Intepretation Steps

Identitfy resting state what your base Observe what is activated once activitiy beigns Analze ampliteud: to what strength Look for patterns and if has consistency

A normal eMg shows what is normal and abornormal Muscle action is a result of analysing Electrical signal: Muscular contraction Rapid action means signals Cacliium release: Bings to protein to allow myosin to attach to activ Actin to form Cross bridges to alow myosin to pivot and pull

Sliding Filament Model

• Made up of repetitive sarcoremors shorting down Neuromuscular Junction(NMJ): to release the action Tetanus: when potentionsal are rapid you see sustained activity. Force Gen: Can be influenaced in number of units to create tension

Spatial Summonation: multiple neuroons stimualte in synchonrized moveemtn Temporal ummnation: Sngularly nueroans fre quuicker which in turn provide sustained action Function:

• Role of stretch receptors and sponal reflects when coordinating limb movement.
• Helps maintain feedback to central ervous systesm, for for unining

The Role: when stetch are set to cord that help muscles with

• Help maintains posture and balance.
• Help avoid strain for tendon or muscle for harm.

This quiz explores vasodilation's impact on blood flow, pressure, and compensatory mechanisms. It covers regional vasodilation during exercise, gravitational effects on blood flow, and the role of chordotonal organs in organisms. Also included are questions on stimuli and systemic blood pressure maintenance.