5.1.5- Animal and Plant Responses Flashcards
where is the cerebrum in the brain?
the folded top part of the brain
what is the function of the cerebrum
Controls voluntary actions
Eg-learning, memory, personality and consciousness
where is the hypothalamus in the brain?
next to the piturity gland
What is the function of the hypothalamus?
Regulatory centre for osmoregulation and temperature balance
where is the cerebellum?
the swirly part at the bottom of the brain.
what is the function of the cerebellum?
Controls unconscious functions, such as balance, posture and non-voluntary movement.
Where is the medulla oblongata in the brain?
the stem at the bottom
What is the function of the medulla oblongata?
Used in autonomic control, eg- heart rate and breathing rate
Where is the puiturity gland?
next to the hypothalamus, bottom front
What is the function of the puiturity gland?
Stores and releases hormones that regulate many body functions.
What is the knee jerk reflex?
-spinal reflex
-doctors use to it to see how the nervous system is working.
-patella tapped so patella tendon stretches (stimulus)
-this initiates the reflex arc
-contraction of extensor muscle above thigh
-absense of reflex= cereballar disease
What is the blinking reflex?
-involuntary blinking
-it protects the eye from damage
What are the 3 types of muscle?
-skeletal muscle
-cardiac muscle
-smooth muscle
What is skeletal muscle?
-also known as voluntary/striated muscle
-regularly arranged so contracts in one direction
-long cylindrical multinucleate fibres.
-contracts quickly, fatigues quickly
-contraction controlled by the somatic nervous system
-short length of contraction
What is the function of the skeletal muscle?
To move the bones of the skeleton about the joints
What is the cardiac muscle?
-surrounds the heart
-single cylindrical branched cells, separated by intercalated discs
-each cell has own nucleus
-striated
-contracts quickly, does not fatigue
-contraction is controlled by the autonomic nervous system and the myogenic control
-intermediate length of contraction
What is the function of cardiac muscle?
Causes the heart to contract and relax, so it can pump blood around the body.
What is smooth muscle?
-spindle shaped, unstriated, single nucleus
-contracts slowly, fatigues slowly
-can remain contracted for a long time
-contraction is controlled by the autonomic nervous system
What is the function of the smooth muscle?
-peristalsis in the gut walk
-pupil dilation and constriction in the eye
-vasodilation and vasoconstriction in the arterioles.
What is a neuromuscular junction?
A specialised synapse which occurs at the end of a motor neurone, where it meets a muscle fibre
What is the order of action at a neuromuscular junction?
*in the pre-synaptic neurone, everything is the same as as a synapse.
-when neurotransmitter diffuses across membrane, it causes depolarisation, which travels along the muscle, and down the tubule
-this causes the sacroreticulum’s membrane to also depolarise, which releases calcium ions
-these calcium ions move into the myofibril, which begins the contraction of the muscle
What is the A band of a myofibril?
Where actin and myosin remain
What is the H zone of a myofibril?
Where only myosin occurs
What is the I band of a myofibril?
Where only actin occurs
What is the M line of a myofibril?
A protein which anchors the myosin filaments
What is the Z line of a myofibril?
A protein that anchors the actin filaments
In a myofibril, what are the widths of actin and myosin like?
Actin= thinner line
Myosin= thicker line
what are the two proteins present in a myofibril called?
actin and myosin
what do actin and myosin give a muscle?
give striated muscles their distinct banding
explain the structure of actin?
-each actin filament is made up of two actin molecules
-made up of globular beads
-the two actin molecules are coiled around each other (like strings of beads)
-tropomyosin and troponin
explain the structure of mysoin?
-each filament is made up of 200 myosin molecules
-each molecule has 2 protruding heads and a long tail
-the heads contain ATPase
-resting myosin heads are bound to ADP and Pi
what are the 8 stages of the sliding filament of muscle contraction?
-when an AP arrives at NMJ, SPR releases calcium ions
-calcium ions bind to troponin
-troponin changes shape
-troponin pulls tropomyosin away from actin binding sites
-myosin head binds to the actin binding site forming a cross-bridge
-myosin head bends 45 degrees, pulling actin filament (releasing bound ADP and Pi)
-ATP is used to break cross-bridge, when it binds to the myosin head, causing it to detach from the actin
-myosin head straightens so becomes free to form a new cross-bridge further along the actin. The hydrolysis of ATP that recocks the head, so it ready to bind again at original position
THIS REPEATS
when muscles contract, what regions gets shorter?
-sarcomere
-H zone
-I band
during muscle contraction, what happens to the Z lines?
they move closer to one another