5.1.5 Animal Responses Flashcards
Brain protection
Skull and also surrounded by protective membranes called meninges
5 main areas of the brain
Cerebrum
Cerebellum
Medulla Oblongata
Hypothalamus
Pituitary gland
Cerebrum
Controls voluntary actions such as learning memory personality and conscious thought
Cerebellum
Controls unconscious functions such as posture, balance and non-voluntary movement
Medulla Oblongata
Used in autonomic control for controlling heart rate and breathing rate
Hypothalamus
Regulatory centre for temperature and water balance
Pituitary gland
Stores and releases hormones that regulate many body functions - master gland
What does cerebellum look like?
Leaf at the back
What does medulla Oblongata look like?
Area at the base of the brain in front of cerebellum
Pituitary gland and hypothalamus
Next to each other in the centre of the brain - looks a bit like an earlobe
Cerebrum
Main grey matter at the top of the brain
Cerebrum properties?
Highly convoluted which increases its surface area considerable and thus its capacity for complex activity
How is the cerebrum split?
Left and right halves known as cerebral hemispheres - each one controls one half of the body and has discrete areas which perform specific functions
Where do the most sophisticated processes occur?
Frontal/prefrontal lobe of cerebral cortex
What are association areas?
Parts of the brain to which neurones are passed on to - size of sensory area is proportional to relative number of receptor cells present
In the base of the brain?
Impulses from each side of the body cross and the hemispheres receive impulses from the opposite side of the body - input from the eyes - thus able to judge distance and perspective
Cerebellum
Control of muscular movement and balance ; coordinates movement - receives information from the organs of balance in the ears and information about the tone of muscles and tendons - relays this info to the areas of the cerebral cortex
Medulla Oblongata
Regulatory centres of the autonomic nervous system - control reflex activities such as ventilation and heart rate
Hypothalamus
Main controlling region for the autonomic nervous system - one parasympathetic and one sympathetic nervous system
Hypothalamus functions
Controlling sleeping/aggression/feeding
Monitoring composition of blood plasma (water and glucose)
Produces hormones - endocrine gland
Pituitary gland
Anterior pituitary - produces hormones like FSH
Posterior pituitary - stores and releases hormones produced by hypothalamus like ADH
Reflex action
Involuntary response to a sensory stimulus
Reflex arc sequence
Receptor - detects stimulus and creates action potential in sensory neurone
Sensory neurone - carries impulse to spinal cord
Relay neurone - connects sensory neurone to the motor neurone within spinal cord/brain
Motor neurone - carries impulse to the effector to carry out the appropriate response
What type of neurones pass impulses across the spinal cord
Relay neurones
Knee jerk reflex
Spinal reflex - only goes up to the spinal cord not the brain ; when leg is tapped just below the patella it stretches the patellar tendon and acts as a stimulus - initiates a reflex arc that causes extensor muscle on thigh to contract
Relay neurone inhibits the motor neurone of the flexor muscle causing it to relax - this contraction coordinated with the relaxation of the antagonistic flexor hamstring causes the leg to kick
Blinking reflex
When cornea is stimulated - also occurs when loud sounds/bright light is seen ; it is an optical reflex while the blinking reflex is a cranial reflex - occurs in the brain, not the spinal cord
When the cornea is irritated?
Stimulus triggers an impulse along a sensory neurone (5th cranial nerve) - impulse then passes through a relay neurone and they are then sent along branches of the motor neurone (7th cranial nerve) to initiate a motor response to close the eyelids
What kind of response does the blinking reflex produce?
Consensual response - both eyes are closed in response to the stimulus
When do doctors test for the blinking reflex?
When examining unconscious patients - if reflex is present it indicates the lower brain stem is functioning, this procedure is therefore used as part of an assessment to determine whether or not a patient is brain-dead
If corneal reflex is present
Cannot be described as brain dead
Reflexes are essential for survival?
Avoid being harmed/reduce severity of any damage - iris contracts the pupil in bright light to prevent damage to the retina and the reverse occurs in dim light to see as much as possible
How do reflexes increase chances of survival?
By being involuntary responses - decision making regions are not involved thus able to deal with more complex responses and prevents the brain from being overloaded
Not having to be learnt - present at birth
Extremely fast - reflex arc is very short - only involves one or two synapses
Reflexes are what we would consider everyday actions such as those which keep us upright
Types of muscle
Skeletal
Cardiac
Involuntary
Skeletal muscle
Make up the bulk of the body muscle tissue - cells responsible for movement
Cardiac muscle
Only found in the heart and myogenic - contract without the need for nervous stimulus
Involuntary muscle
Smooth muscle - involuntary muscle cells are found in many parts of the body like the stomach/bladder - walls of blood vessels/digestive tract for peristalsis
DIFFERENCES BETWEEN MUSCLES
LOOK AT TYPES OF MUSCLES
Muscle fibres
Type of skeletal muscle
Muscle fibres structure
Enclosed within a plasma membrane known as the sarcolemma - muscle fibres contain a number of nuclei and are much longer than normal cells
Muscle fibre
Formed from many embryonic muscle cells fusing together - makes the muscle stronger as the junction between adjacent cells would act as a point of weakness
Sarcomere
Basic functional unit of a fibre
Sarcolemma
Plasmid membrane around the fibres
Sarcoplasm
Cytoplasm shared within fibres - ions to move around
Sarcoplasmic reticulum
Endoplasmic reticulum within sarcomere ; gets depolarised and release calcium ions
Myofibril
Long cylindrical organelles that bring about muscular contraction ; actin + myosin
Darker bands
Myosin - actin distributed around the rest
Packs of myofibrils
Z lines
Separates myosin - SARCOMERE IS BETWEEN TWO Z LINES ; ONE FUNCTIONAL UNIT
Muscle fibre
Many myofibrils with sarcolemma around it containing sarcoplasm and sarcoplasmic reticulum within each one
Actin
Thinner filament
What do we look at muscles through
Electron microscope or x ray diffraction
Overlaps?
Anything that doesn’t have an overlap is light band (anything with myosin is dark)
H zone
Between two actin filaments (within myosin)
What happens in muscle contraction
The dark band stays the same and the light band contracts
Actin molecule describe
Tropomyosin wrapped around it held in place by troop in which binds to Ca2+ ions which always leads to a conformational change ; leads to movement etc
They have dents which are called the actin myosin binding sites
Myosin structure describe
Much thicker
Has several myosin tails with a myosin head at the end ; contains ADP at its resting state - also contains an ATPase component which can hydrolyse ATP to ADP +pi
Can forms cross bridges with actin (binding sites)
Mechanism of sliding filament model
Stimulation
Attachment
Detachment
Stimulation
Action potential arrives and depolarises sarcolemma and sarcoplasmic reticulum - opens ca2+ ions released from the reticulum into sarcoplasm which can bind to troponin
What does binding do?
Conformational change - pulls tropomyosin and exposes actin myosin binding sites
Attachment
Myosin head binds to actin myosin binding site forming cross bridges - myosin filament flexes and pulls actin along AND RELEASES ADP FROM MYOSIN HEAD
Detachment
ATP can now bind to myosin head (since ADP gone) and this causes it to detach from binding site
Calcium ion binds to myosin head activating ATPase which hydrolysis ATP into ADP giving it energy to return back to original position
Where is energy used
IN RETURNING MYOSIN HEAD BACK TO ORIGINAL POSITION
What happens at the end
Now allowed to bind to NEXT binding site and whole process repeats itself
Skeletal muscle structure
Bands of actin myosin
Multinucleated
Cylindrical cells
Smooth muscle structure
Non-striated
Uninucleated
Cardiac muscle cellular structure
Branched cells - uninucleated - STRIATED
Function of skeletal muscle
Move bones/skeleton/joints
Smooth muscle function
Pupil size
Controlling diameter of arteries/arterioles/bronchi
Peristalsis
Function of cardiac muscle
Pump blood
