Plant And Animal Responses Flashcards
What alters the frequency of the excision waves?
The cardiovascular centre
Where do you find the cardiovascular centre?
In the medulla oblongata
What are the 2 nerves that alter heart rate?
Accelerans and Vagus
Which neurotransmitter increases heart rate?
Noradrenaline
Which neurotransmitter decreases heart rate?
Acetylcholine
Which neurotransmitter is released by the vagus nerve?
Acetylcholine
Which neurotransmitter is released by the accelerans nerve?
Noradrenaline
What is the function of the cardiovascular centre?
To coordinate an appropriate output to effect the heart rate when inputs from environment are received
What are the two input receptors to the cardiovascular centre?
Chemoreceptors
Stretch receptors
Where can stretch receptors be found?
In the muscles and carotid sinus
What is the function of the stretch receptors in the muscle?
They detect movement of limbs. To inform that extra oxygen may be needed. Leads to an increase in heart rate.
Function of chemoreceptors?
Monitor pH of blood
Where are chemoreceptors found?
In the carotid artery
Where is the carotid sinus?
In the carotid artery
Example of when chemoreceptors will send action potentials?
During exercise more carbon dioxide is produced from respiration. This combines with water to make a weak carbonic acid. Chemoreceptors will send action potential to increase heart rate.
Fuction of stretch receptors in carotid sinus?
Monitors blood pressure
How do stretch receptors respond?
If blood pressure becomes too high the stretch receptors will send action potential to lower heart rate
What are the 3 types of muscle?
Skeletal, cardiac and involuntary
Other words for skeletal muscle?
Striated or voluntary
Describe Involuntary smooth muscle diagram?
Individual cells- each containing a nucleus and bundles of actin and myosin
Spindle shaped
At rest- 500 micrometers long and 5 micrometers wide
Describe involuntary muscle contractions?
Contracts slowly and regularly. Does not tire quickly.
What system controls smooth muscle?
The autonomic system
Where is involuntary muscle found?
In the walls of tubular structures
Eg- blood vessels and digestive system
How is involuntary muscle arranged?
In longitudinal and circular layers that oppose eachother
Describe cardiac muscle?
Individual cells form fibres which branch to form cross bridges
Why is cardiac muscle arranged the way it is?
The cross bridges ensure that electrical stimulation spreads evenly over the walls and chambers. Also to ensure a squeezing action.
How are the cells in cardiac muscle joined?
By intercalated discs
What are intercalated discs?
Specialised cell surface membranes fused to produce gap junctions to allow diffusion between cells
Function of intercalated discs?
Allow for rapid pass of action potentials across the cardiac muscle fibres
Other facts about cardiac muscle?
Myogenic
Doesn’t fatigue easily
How does skeletal muscle cause movement?
Contraction of the muscle causes bending or straightening of the joint
How is skeletal muscle arranged?
In antagonist pairs
When one contacts the other elongates
Describe the skeletal muscle cells?
Contains sarcoplasm
Many mitochondria
An extensive sarcoplasmic reticulum
Describe the skeletal muscle fibres?
100 micrometers in diameter
Multinucleate
Surrounded by a membrane called sarcolemmaa
How are the skeletal fibres arranged?
Into myofibrils- divided into a chin of subunits called sarcomeres
How are actin and myosin arranged?
In a banded pattern
Gives striated appearance
How does skeletal muscle contract?
Quickly and powerfully
Fatigues easily
What are the 2 types of protein filaments?
Thin filaments- light band
Thick filaments- dark band
What does the z line do?
Holds together the thin filaments
Do the filaments overlap?
Yes, except in the middle of the dark band (the H zone)
What is the distance between two z lines?
Sarcomere
What are the filaments surrounded by?
A sarcoplasmic reticulum
What are the thin filaments?
Actin
What other molecules does the thin filaments consist of?
Troponin
Tropomysin
Describe troponin?
Globular protein
Consists of 3 polypeptides
Function of troponin?
Has 3 binding sites to bind to actin, tropomysin, and calcium
What is tropomyosin?
Wound around actin
At rest what do troponin and tropomysin do?
Cover the binding sites
What does the thin filament consist of?
Bundle of myosin molecules
Describe the myosin molecules?
Has a mobile protruding head at each end
Why are the myosin heads mobile?
To bind to actin molecule binding sites when exposed
Sliding filament hypothesis?
Light bands and H zone shortens, z bands get closer, sarcomere gets shorter
Thin and thick filaments slide past eachother
Stimulation of contraction step 1?
Action potential arrives at axon which causes calcium ion channels to open
Stimulation of contraction step 2?
Vesicles containing acetylcholine fuse with membrane
Stimulation of contraction step 3?
Acetylcholine molecules diffuse across gap and fuse with sarcolemma receptors
Stimulation of contraction step 4?
Sodium ion channels open. Sodium ions enter the muscle fibres causing depolarisation of the sarcolemma
Stimulation of contraction step 5?
The wave of depolarising travels down tubules
Which system stimulates the skeletal system?
Somatic
What is the neuromuscular junction?
The junction between the nervous system and muscle
What is a mortor unit?
When many motor neurones divide to connect to several muscle fibres which all contract together to provide a stronger contraction
Control of contraction step 1?
Arrival of action potential at sarcoplasmic reticulum causes the release of calcium ions into sarcoplasm
Control of contraction step 2?
The calcium ions bind to the triopin which alters the shape causing the tropomysin to expose binding sites
Control of contraction step 3?
Myosin head binds to actin to form cross bridges between fibres
Control of contraction step 4?
Myosin head tilts backwards to cause actin molecule to slide past
What is the role of ATP in the muscle contraction?
The ATP is hydrolysed to ADP and inorganic phosphate to release energy allowing the myosin heads to move
How does ATP get hydrolysed?
By part of the myosin head acting as ATPase
Which 3 ways is ATP generated?
Aerobic respiration- many mitochondria in muscle tissue
Anaerobic respiration
Creatine phosphate
Problem with anaerobic respiration?
Short term
Produces lactic acid- causes fatigue
Where does anaerobic respiration occur?
In the sarcoplasm
Where is creatine phosphate?
In the sarcoplasm
How does creatine phosphate generate ATP?
The phosphate can be transferred to ADP molecules to form ATP
What enzyme in involved in ATP production from Creatine phosphate?
Creatine photophotransferase
Where are calcium ions stored in the muscle?
In the sarcoplasmic reticulum
What must communication systems do?
Detect changes in the environment
Carry out cell signalling
Co-ordinate effectors
Initiate responses
What are the divisions of the nervous system?
CNS
PNS
What are the divisions of the PNS?
The motor system
The sensory system
What does the motor system divide into?
Somatic nervous system
Autonomic nervous system
What does the CNS divide to?
Brain and spinal chord
What is the spinal chord made up of?
Many non-myelinated neurones.
What is the role and composition of PNS?
Ensures rapid communication between sensory receptors, the CNS and effectors
Composed of motor and sensory neurones
Describe the somatic nervous system?
Under voluntary control
Myelinated
One single motor neurone connecting CNS to effector
Describe the autonomic nervous system?
Not voluntary
Non- myelinated
2 neurones connecting CNS to effector
Role of sympathetic system?
Prepares body for activity
Role of parasympathetic system?
Conserves energy
Role of sympathetic system?
Increases HR and BR
Dilates pupils
Reduces digestive activity
Role of parasympathetic system?
Decreases HR and BR
Constricts pupils
Increases digestive activity
What is a reflex action?
A response to a stimuli which does not require brain processing to coordinate a response
Example of reflex actions?
Knee jerk
Blinking
What is a reflex arc?
When receptor and effector are in the same place
What may stimulate blinking?
Foreign object touching the eye- corneal reflex
Sudden bright light- optical reflex
Loud sounds
Sudden movements close to the eye
Sympathetic system?
Ganglia outside the CNS
Short pre-ganglionic neurones
Long post ganglionic neurones
Uses noradrenaline
Parasympathetic system?
Uses acetylcholine
Short post-ganglionic neurones
Long pre-ganglionic neurones
Ganglia in effector tissue
