Animal Responses Flashcards
(13 cards)
Cerebrum
Largest part of the brain, outer layer is known as cerebral cortex. Made up of many fold and split into two hemispheres. Functions controlling conscious thoughts, language, intelligence, personality
Cerebellum:
Mini cauliflower
Coordinating movement, posture and balance
Medulla oblongata
Above the spinal cord, centre for unconscious activities e.g breathing, heart rate
Hypothalamus:
Homeostasis, thermoregulation and osmosis regulation
Pituitary gland:
Small lobe known as master gland. Stimulates teh releases of hormones form other gland in the endocrine system\
Secretes many hormones to coordinate several responses including osmoregulation
What is involved in a reflex arc?
Receptor, Sensory neurone, relay neurone, motor neurone ,effector
Synapses between arc are where electrical energy is converted to chemical and diffuse across
No conscious desicions is involved
Only two synapses means response is rapid
Fight or flight response:
Autonomic responses are triggered
Autonomic nervous system detects the potential threat, sending an impulse to the hypothalamus
Results in the sympathetic branch of the nervous system transmitting more impulses
Effectors are adrenal glands which releases adrenaline and noradrenaline which trigger hypothalamus to stimulate the release of ACTH from the pituitary gland
Adrenaline is the first messenger, it attaches to receptor on teh surface of target cells. This causes teh G protein to be activated and adenylyl cyclase to convert ATP into cAMP, cAMP activates and enzyme that hydrolyses glycogen into glucose.
CAMP is teh second messenger
Control of the heart rate:
Endocrine and nervous system both affect heart rate
Heart have inbuilt pace maker, sino atrial node and is myotonic. Howver still effected by endocrine and nervous system
Hormonal control:
Adrenaline increases heart rate, increases stroke volume and increases cardiac output.
Nervous system control:
Medulla oblongata controls heart rate by autonomic nervous system . Connected to SAN in heart via accelerator and vagus nerve
- heart rate increased by impulses sent via accelerator nerve in sympathetic NS
- decreased by impulses sent via vagus nerve in parasympathetic NS
Homeostatic control:
Heart rate changes in response to pH and pressure. Detected by chemoreceptors and baroreceptors in carotid artery and aorta.
Ph decreases when there is lots of respiration. CO2 or lactic acid needs to be removed rapidly to prevent damage to enzymes. This means heart rate needs to increase in order to increase breath rate so coz diffuses more rapidly into alveoli
If blood pressure is too high, this can damage the walls of the arteries. More impulses sent in parasympathetic vagus nerve slow down heart rate Heart. If pressure Eid too low, opposite
Muscles (3)
Skeletal: connected to skeleton and responsible for moving the skeleton. Made out of cylindrical shapes which join to make multinucleated myofibrils. Striated pattern
Cardiac: muscle in the heart. It is uninucleated, myogenic. Cells are branches to allow contraction across whole of atrium or ventricular. Striated pattern
Smooth (involuntary) muscle: lines organs and blood vessel. Casey’s movemnt of organs or blood vessels e.g vasoconstrictions or dilation. Uninucleated, spindle shaped and unstriated
Neuromuscular junction:
Junction between motor neuron and muscle
When an impulse arrives at end of motor neurone. Neurotransmitter passes across and binds to receptors on sarcolemma. This causes receptors to open, sodium ions move in and membrane becomes depolarised. Wave of depolarisation passes down t tubules in sarcoplasmic reticulum causes it to release calcium ion which leads to muscle contraction.
Similarities to synaptic junction:
- unidirectional
- neurotransmitter action
Differences:
- only excitatory while synaptic could be excitatory or inhibitory
- connect neurone to muscle no tneurone to neurone
- end point for action potential
- acetylcholine binds to receptors on muscles fibre membrane
Muscle make up:
Muscles act in antagonistic pairs against an incompressible skeleton to create movement. This can be automatic or controlled by conscious thought.
Myofibrils are subcellular structures designed for contractions. High number of mitochondria
They are made up of sarcomere made of actin and myosin which collectively bring about force to cause movement.
Sliding filament theory:
- Action potential is stimulated in a muscle
- Calcium ions enter and bind to protein troponin, causing a change in the shape of tropomyosin which moves to uncover the binding sites on actin for myosin heads to bind to
- ADP is attched to myosin head and hyosin head binds to actin to form a cross bridge
- The angle created in the cross bridge creates tensions and as a result the actin filament is pulled and slides along myosin. Doing so, ADP molecule is released
- ATP molecule binds to myosin head and causes it to change shape,m as a result, it detaches from actin
- Within the sarcoplasm the enzyme ATPase is activated by calcium ions to hydrolyse the ATP on the myosin head into ADP and release enough energy for the myosin head to return to its original position
- This process continue to happen as long as calcium ions remain high and muscle remains stimulated by nervous system
How do muscles generate ATP using phosphocreatine?
Phosphocreatine is stored in muscles, it provides the phosphate to regenerate ATP from ADP
