Animal Responses

What is the central nervous system (CNS)?

The CNS consists of the brain and spinal cord.

What is the peripheral nervous system (PNS)?

The PNS is made up of nerves that connect the CNS to the rest of the body.

What does the somatic nervous system control?

It controls conscious activities, such as running and playing video games.

What does the autonomic nervous system control?

It controls unconscious activities, such as digestion.

What is the function of the sympathetic nervous system?

It prepares the body for action; it is the 'fight or flight' system.

What is the function of the parasympathetic nervous system?

It calms the body down and promotes 'rest and digest' activities.

What do sympathetic nerves do?

They increase heart rate by releasing noradrenaline.

What do parasympathetic nerves do?

They decrease heart rate by releasing acetylcholine.

What are the five main regions of the human brain?

The cerebrum, hypothalamus, pituitary gland, cerebellum, and medulla oblongata.

What is the cerebrum and what is its function?

The largest part of the brain, responsible for conscious activities like vision, hearing, speech, thinking, and memory.

How much of the brain’s mass does the cerebrum account for?

About 80%.

Into how many lobes is the cerebrum divided?

Five lobes.

What joins the two cerebral hemispheres together?

The corpus callosum, a band of nerve fibres.

Which side of the body does the right cerebral hemisphere control?

The left side.

Which side of the body does the left cerebral hemisphere control?

The right side.

What is the cerebral cortex?

The thin, highly folded outer layer of the cerebrum also called grey matter

Why is the cerebral cortex highly folded?

To increase surface area and allow more neurones and connections.

What is found beneath the cerebral cortex?

White matter, made of myelinated axons.

What is the hypothalamus?

Part of the brain that controls body temperature and hormones.

What does the hypothalamus monitor?

It checks the blood to control body temperature and hormones.

What are three main functions of the hypothalamus?

Regulating body temperature, osmoregulation, and controlling endocrine functions.

How does the hypothalamus regulate body temperature?

By monitoring blood temperature and initiating homeostatic responses.

How does the hypothalamus help with osmoregulation?

By monitoring blood concentration and stimulating the release of ADH if needed.

What is the function of the pituitary gland?

Produces and releases hormones that regulate body processes or stimulate other glands.

What are the two parts of the pituitary gland?

The anterior pituitary and the posterior pituitary.

What does the anterior pituitary do?

Produces and releases its own hormones.

What does the posterior pituitary do?

Stores and releases hormones produced by the hypothalamus.

Where is the cerebellum located and what is its function?

Below the cerebrum; it controls motor coordination and balance.

Are the actions controlled by the cerebellum voluntary or involuntary?

Involuntary (subconscious).

Where is the medulla oblongata found?

At the base of the brain, where it joins the spinal cord.

What are the three centres found in the medulla oblongata?

The cardiac centre, vasomotor centre, and respiratory centre.

What does the cardiac centre in the medulla control?

Heart rate.

What does the vasomotor centre in the medulla control?

Blood pressure.

What does the respiratory centre in the medulla control?

Breathing rate.

What hormones does the posterior pituitary gland store and release?

ADH and oxytocin

What is the main function of the anterior pituitary gland?

It produces and releases its own hormones.

What is a reflex?

A rapid, automatic response to a stimulus that does not involve conscious processing by the brain.

What triggers the blinking reflex?

Sensory nerve endings in the cornea are stimulated by touch.

What happens after the cornea is stimulated in the blinking reflex?

An impulse is sent along a sensory neuron to a relay neuron in the medulla oblongata.

How is the blinking reflex completed?

Motor neurons send impulses to the orbicularis oculi muscles via the facial nerve, causing the eyelids to close.

What is the function of the orbicularis oculi muscle?

It contracts to close the eyelids during the blinking reflex.

What is the function of the levator palpebrae superioris muscle in blinking?

It raises the upper eyelid; during blinking, it is inhibited to allow the eyelid to close.

What initiates the knee-jerk reflex?

Stretch receptors in the quadriceps detect muscle stretching.

How does the knee-jerk reflex work?

The sensory neuron sends an impulse directly to a motor neuron in the spinal cord, which causes the quadriceps to contract.

What is the result of the knee-jerk reflex?

The lower leg moves forward due to quadriceps contraction.

What triggers the fight or flight response?

Nerve impulses arriving at the hypothalamus activate the hormonal and sympathetic nervous systems.

How does the pituitary gland contribute to the fight or flight response?

It releases ACTH, causing the adrenal cortex to release steroid hormones.

What hormone is released by the adrenal medulla during fight or flight?

Adrenaline.

How does adrenaline affect the heart during fight or flight?

It increases heart rate and stroke volume.

How does adrenaline affect breathing?

It relaxes muscles around the bronchioles, allowing deeper breathing.

How does adrenaline affect energy availability?

It converts glycogen to glucose, increasing respiration.

How does adrenaline affect the skin during fight or flight?

It causes arterioles supplying the skin to constrict and erector pili muscles to contract.

How does adrenaline affect blood flow to muscles?

It dilates arterioles supplying the heart, lungs, and skeletal muscles.

What is the sinoatrial node (SAN)?

A group of cells in the heart that generate electrical impulses causing cardiac muscle contraction.

How is heart rate controlled?

The medulla oblongata unconsciously controls the rate at which the SAN fires.

What receptors detect internal stimuli affecting heart rate?

Baroreceptors (pressure) and chemoreceptors (chemical).

How does the medulla respond to high blood pressure?

Baroreceptors send impulses to the medulla, which sends signals via the vagus nerve releasing acetylcholine to decrease heart rate.

How does the medulla respond to low blood pressure?

Baroreceptors send impulses to the medulla, which sends signals via the accelerator nerve releasing noradrenaline to increase heart rate.

How does the medulla respond to high blood pH?

Chemoreceptors detect high pH; the medulla signals via the vagus nerve to decrease heart rate.

How does the medulla respond to low blood pH?

Chemoreceptors detect low pH; the medulla signals via the accelerator nerve to increase heart rate.

What is the Student's t-test used for?

To determine if there is a significant difference between the means of two data sets.

When do you reject the null hypothesis using the Student's t-test?

When the calculated t-value is greater than the critical value at p < 0.05.

What are the main effects of adrenaline on the body?

Increases heart rate and stroke volume, converts glycogen to glucose, affects blood flow, and dilates bronchioles.

How does adrenaline affect heart contraction?

It causes the heart to contract more rapidly and forcefully.

What are muscle fibres?

Large bundles of long, multinucleated cells specialized for contraction.

What is the sarcolemma?

The cell membrane of a muscle fibre.

What are transverse (T) tubules?

Folds of the sarcolemma that help spread electrical impulses into the muscle fibre.

What is the sarcoplasmic reticulum?

An organelle that stores and releases calcium ions for muscle contraction.

Why do muscle fibres have many mitochondria?

To provide ATP required for muscle contraction.

Why are muscle fibres multinucleate?

They contain many nuclei to support their large cytoplasmic volume.

What are myofibrils?

Cylindrical organelles within muscle fibres specialized for contraction.

What do myofibrils contain?

Bundles of thick (myosin) and thin (actin) myofilaments.

What are thick myofilaments made of?

The protein myosin.

What are thin myofilaments made of?

The protein actin.

What are A-bands (dark bands)?

Regions containing thick myosin filaments and overlapping thin actin filaments.

What are I-bands (light bands)?

Regions containing only thin actin filaments.

What are sarcomeres?

The short contractile units that make up myofibrils.

What is the Z-line?

The boundary at each end of a sarcomere.

What is the M-line?

The line in the centre of the sarcomere, in the middle of the myosin filaments.

What is the H-zone?

The region within the A-band that contains only myosin filaments.

What happens during the sliding filament theory?

Actin and myosin filaments slide past each other, shortening the sarcomere and causing muscle contraction.

What happens to the bands in the sarcomere as it contracts?

The A-band remains the same length, while the I-band and H-zone become shorter.

What are some features of myosin filaments?

They have globular heads that bind to actin and ATP.

What proteins regulate the interaction between actin and myosin?

Tropomyosin and troponin.

What happens to the actin-myosin binding sites in resting muscle?

The binding sites are blocked by tropomyosin.

What is the first step of how an action potential triggers muscle contraction?

The action potential depolarizes the sarcolemma.

What is the second step of how an action potential triggers muscle contraction?

The depolarization spreads down T tubules to the sarcoplasmic reticulum.

What is the third step of how an action potential triggers muscle contraction?

This triggers the release of stored calcium ions into the sarcoplasm.

What is the fourth step of how an action potential triggers muscle contraction?

Calcium ions bind to troponin, causing tropomyosin to move and exposing the actin-myosin binding sites.

What role does ATP play during muscle contraction?

ATP is required for myosin heads to detach from actin and reattach to a new binding site, enabling repeated contraction cycles.

What happens when the muscle stops being stimulated?

Calcium ions are actively transported back into the sarcoplasmic reticulum.

What is a neuromuscular junction?

A synapse between a motor neuron and a muscle fibre, where acetylcholine is the neurotransmitter.

What happens if a chemical blocks neurotransmitter release at the neuromuscular junction?

It can prevent action potentials in the muscle, potentially affecting muscles involved in breathing.

What is skeletal muscle?

Voluntary, striated muscle responsible for movement, posture, and maintaining body position.

What is involuntary muscle?

Non-striated muscle found in the walls of internal organs; it contracts slowly and is not under conscious control.

How can muscle contractions be measured electrically?

By using electromyography (EMG) to record an electromyogram trace.