5.1.5 Animal Responses COMPLETE Flashcards
What does the nervous system split into?
- Central Nervous System
- Peripheral Nervous System
CNS
Consists of relay neurones
Contains both white and grey matter
Thousands of synapses
PNS
Everywhere but the CNS
Consists of sensory and motor neurones
Glial Cell
Cells that are needed in the nervous system but are not neurones
What does the Peripheral Nervous System split into?
- Autonomic Nervous System
- Somatic Nervous System
Autonomic Nervous System
Involuntary
Controls homeostatic mechanisms
Stimulates Cardiac + smooth muscle, Glands
Somatic Nervous System
Voluntary
Controls conscious activities
Stimulates skeletal muscle
What does the Autonomic Nervous System split into?
Sympathetic and Parasympathetic
Sympathetic
Prepares the body for actions
Used when stressed
Fight or flight response
Parasympathetic
Prepares body for being calm
Rest and digest
Somatic Neurones
Consists of one neurone, mostly myelinated
Have an excitatory effect on skeletal muscles
Autonomic Neurones
Consists of two neurones linked at a ganglion
Excitatory and inhibitory effect
More myelinated
Postganglionic neurone
Unmyelinated side of the neurone
Describe the relationship between the parasympathetic and sympathetic
Antagonistic
Sympathetic body responses
Increased Heart rate
Dilating pupils
Decreased Peristalsis
Erector muscles contract
Parasympathetic body responses
Decreased Heart rate
Constricting pupils
Increased Peristalsis
Erector muscles relax
Structure of Sympathetic nervous system
Ganglion is just outside the spinal chord
Pre ganglionic neurone is very short
Use Noradrenaline
Structure of Parasympathetic nervous system
Ganglion is within the target tissue
Vary considerably
Use Acetylcholine
Cerebrum
Emotions, movement, visual processing, memory, speech
Cerebellum
Responsible for coordination, balance, posture
Medulla Oblongata
Coordinates and controls involuntary muscle
Hypothalamus
Controls the autonomic nervous system, receives sensory input from temp receptors. Regulates pituitary gland
Pituitary Gland
Anterior region produces 6 hormones such as FSH
Posterior region stores and releases hormones
DEFINITION- A Reflex
A rapid involuntary response to a stimulus, doesn’t involve conscious part of the brain, aims to minimise damage to body.
Example of Reflexes
Expulsion- Sneezing, vomit
Withdrawal Reflex- Pull away from heat
Dilation of pupils
Babies hold their breath
Corneal Reflex
When your eyelids shut to protect the cornea from damage, occurs after loud sounds, bright lights and touch.
Explain Blinking Reflex
Sensory neurone from the cornea sends an impulse ti the brain stem, this synapses with an intermediate neurone. A motor neurone then causes facial muscles to contract making eyelids blink.
Knee Jerk Reflex
- Patella tendon is stretched, receptors detect the increase in muscle length (muscle spindles)
- Sensory neurone stimulates a motor neurone
- Extensor muscle contracts so leg straightens
- Also relaxes as relay neurone inhibits the flexor muscle
Physiological changes to fight or flight
- Pupils dilate
- Heart Rate increases
- Metabolic Rate
- Erector muscles contract
Cardiac Muscle
Is myogenic as initiates its own contractions
SAN
Region of tissue that can initiate an action potential, excitations travel over atrial walls then goes down the AVN. Then down the purine tissue to the ventricles so they contract.
Medulla Oblongata- Control of the heart
Alters the heart rate as required, linked to the SAN via motor neurones.
Sympathetic Nerve, action potentials will increase the heart rate
Parasympathetic Nerve, action potentials will decrease the heart rate
Stretch receptors in muscles
Detect movement of limbs, indicating more O2 will be needed and a higher heart rate
Baroreceptors in Carotid Artery
Detect change in pressure, if too high the heart rate will decrease.
Chemoreceptors
Found in the brain, aorta and carotid artery. Detect change in pH from CO2. Increased heart rate will decrease the H+ concentration
Hormonal Control of Heart Rate
Adrenaline binds to specific receptors in cardiac muscle. Increasing the force and rate of the heart beat.
Voluntary Muscle (Skeletal)
Striated with bands of actin and myosin. Multinucleate and cylindrical shape .Move bones at joints so found within limbs and the intercostal muscles.
Involuntary Muscle (Smooth)
Non striated and spindle shaped cells, uninucleate. Control diameter of arteries, peristalsis urine contractions. Found din bronchi, arteries, gut, oesophagus
Cardiac Muscle
Striated and branched cells with intercalated discs, uninucleate. Pump blood around the body with myogenic impulse.
Structure of Skeletal Muscle
- Made up of thousands of muscle fibres
- Multinucleate
- Cell surface membrane is called the Sarcolemma
- Cytoplasm is know as Sarcoplasm
- Contain many mitochondria and sarcoplasmic reticulum
- Myofilaments of thin actin and thick myosin
Events at a neuromuscular junction
- impulse causes vesicles to fuse with the presynaptic membrane and release acetylcholine into cleft.
- Diffuses across cleft and binds to receptors on sarcolemma
- Na+ floods in causing depolarisation spreading into T tubules
- Ca2+ channels open and they diffuse out of the Sarcoplasmic reticulum.
- Ca2+ binds to proteins causing contractions
- Acetylcholinesterase breaks it down in the cleft.
The Sarcomere
- Region between the two Z lines
- Shortens when muscles contract
Z Line
Holds together thin actin filaments
M Line
Holds together thick myosin filaments
Thick Myosin Filaments
Are made of of bundles of the fibrous protein myosin, each molecule has a tail attached to the M line and a head.
Thin Actin Filaments
Made up of two helical strands of globular proteins, around this coils a fibrous protein called Tropomyosin. Attached at regular intervals to the tropomyosin and actin are Troponin complexes
The Sliding Filament Model
When Ca ions are released into the Sarcoplasm they bind to the troponin molecules, so it changes shape. Moves the tropomyosin exposing the binding sites.
Cross bridges form as the myosin heads attach to the sites, when they bend it is pulled along so it overlaps causing a power stroke.
ATP caused them to detach and its hydrolysed into ADP and Pi
ATP production for muscle contraction
- Initially ATP is used as an immediate energy source, but not enough is stored.
- Creatine Phosphate from the sarcoplasm is broken down into ATP
- Aerobic respiration uses oxygen and glucose from the blood in the mitochondria for ATP
- Anaerobic respiration used but forms lactic acid.
Electromyograph
Electrodes placed on the skin can detect electrical signals
