C3.1 Integration of body systems SL

System integration

When components communicate + coordinaate

• How diff parts of an organism work tog to perform complex functions

• Happens on multiple levels of organisation

How important is system integration in living systems?

A necessary process

What is coordination needed for?

Component parts of a system to collectively perform an overall function

Hierarchy of subsystems integrated in a multicellular living organism (levels of organisation)

1. Cells

2. Tissues

3. Organs

4. Body (organ) systems

How does a cheetah become an effective predator?

By integration of its body systems

Tissue

Group of 2 or more diff cell types w specialised structures + functions, working + communicating tog

Organ

Group of 2 or more types of tissues working tog to perform a specific function

Organ system

Group of organs working tog to perform a life function

Organism

A living thing made up of multiple integrated + interdependent systems at various levels of organisation

Emergent properties

• Only in multicellular organisms

• Characteristics that arise when smaller components combine to form larger systems

• “whole is greater than the sum of its parts”

What is responsible for emergent properties?

Integration

Integration of organs in animals requires coordination, which requires?

1. Communication via:

   • a) Hormonal signalling

   • b) Nervous signalling

2. Transport of materials + energy

Hormones

• Chemical messengers produced by endocrine glands

• Travel via BS to act on target cells (with the proper receptor)

Nervous signalling

• Uses electrical impulses

• EI transmitted by neurons to specific location

• Effects muscles / glands only

Nervous vs endocrine system in sending messages

Nervous:

• Uses EI

• EI travel via neurons

• Rapid

• V short

• Affects only specific muscles / glands

Endocrine:

• Uses hormones

• Hormones travel via BS

• Slower

• Lasts a longer time (until hormone is broken down)

• Travels to whole body

Examples of systems that transport materials + energy

1. Circulatory system- blood transports oxygenated blood, urea, glucose, hormones

2. Digestive system- food transported from oesophagus to stomach

Brain

• Central information integration organ

• Stores + processes info combined from several inputs (sensory receptors)

• Role in learning + memory

• Sends signals to effector organs via motor neurons if response is needed

Spinal cord

Integrating centre for unconscious processes

• Aka reflexes

2 parts of the nervous system

1. Central NS

2. Peripheral NS (nerves)

Parts of the CNS

• Brain

• Spinal cord

2 main tissues in the spinal cord

1. White matter

2. Grey matter

Functions of white matter (transmission)

Transmit signals from:

i) Sensory receptors to brain

ii) Brain to other organs

What does grey matter contain?

Cell bodies + synapses

Functions of grey matter (processing)

1. Processes info

2. Decision making

3. Unconcious processes only

Concious processes (expand on this)

• Voluntary actions

• Involve awareness + decision-making

• Controlled by the cerebral hemispheres

Unconscious processes (expand on this)

• Occur w/o conscious thought- eg reflexes (rapid, involuntary responses to stimuli)

• Spinal cord = integrating centre for UP

Role of sensory neurons

Convey messages from receptor cells to the CNS

• Msgs = EI

• Sensory receptor → sensory neurons → CNS (brain / spinal cord)

2 groups of receptors + examples

1. External- touch, heat, light

2. Internal- stretch, chemo (pH)

Where does info inputted to the spinal cord / cerebral hemispheres come via?

Sensory neurons

Role of motor neurons

Convey messages (output) from CNS (cerebral hemispheres) to the effectors (muscles)

What happens when the output form a cerebral hemisphere reaches a muscle?

Stimulated to contract

Stimulus

Change in the environment (external / internal) that is detected by a receptor

Receptors

Transform the stimuli into nerve impulses that are transmitted to the brain where decision-making occurs

Reflexes

Involuntary + occur w/o conscious thought

• Don’t involve the brain (receptor → sensory neuron → spinal cord → motor neuron)

Prof of reflexes

No conscious decision making → faster → protects from danger

Motor neurons have cell bodies in the brain close tog but…

Axons + terminals attach to diff effector organs

Functions of diff areas of the brain

In how many directions can neurons transmit info in?

1

Nerve

Bundle of nerve fibres (sensory AND motor neurons) surrounded by a sheath

Myelin

Increases the speed of nerve impulse transmission

Label a nerve with these features:

• Protective sheath

• Myelinated nerve fibres

• Unmyelinated nerve fibres

• Protective sheath

• Myelinated

• Unmyelinated nerve fibres

Example of involuntary responses

Pain reflex arcs

Effector in the pain reflex arc

Skeletal muscle

• Contracts

Reflex arc

Involuntary + rapid response to a specific stimulus

1. Receptor (detects stimuli)

2. Sensory neuron

3. Interneuron (connects SN to MN)(CNS)

4. Motor neuron

5. Effector (muscle / gland)

Pain reflex arc

1. Pain receptor (in hand)

2. Sensory neuron (free sensory nerve ending)

3. 1 interneuron in the grey matter of the spinal cord

4. Motor neuron

5. Effector- skeletal muscle contracts

Explain the reflex arc

need to complete

Role of cerebellum

1. Coordinate skeletal muscle contraction

   • Eg timings of muscle contraction

2. Balance

3. Overall control of body movements

   • Eg things that require muscle memory

   • Posture

Circadian rhythm

Pattern of sleep / wake cycles that organisms are adapted for

• Approx 24 hours

Melatonin

• Hormone secreted by the pineal gland

• Controls circadian rhythms

Diurnal pattern (repeats every 24 hours) of melatonin

1. High at night (dark) → sleepy

2. Low during day (light) → awake

What inhibits melatonin secretion?

Light

How does the diurnal pattern of melatonin help establish a cycle of sleeping + waking?

LIGHT RECEPTOR → CNS → PINEAL GLAND

Day

1. Light receptor in eye

2. Senses light → sends info to CNS via sensory neuron

3. Inhibits melatonin production

Night

1. Light receptor in eye

2. Senses less light → sends info to CNS

3. Promotes melatonin production by pineal gland

4. Melatonin (hormone) → travels via BS to diff target organs

What does melatonin cause?

1. Drop in body temp

2. Drowsiness

3. Sleep

Another name for adrenaline

Epinephrine

Adrenaline (epinephrine)

• Secreted by adrenal glands

• Prepares body for vigorous activity (fight or flight

Goal of adrenaline (epinephrine)

Increase glucose + O2 supply to skeletal muscles

Why does adrenaline increase glucose + O2 supply to skeletal muscles

… needed for:

1. Glucose: energy

2. Oxygen: ATP energy production via aerobic respiration

How do hormones travel to target organs?

Via bloodstream

6 effects of epinephrine (adrenaline) in the body

1. Hydrolysis og glycogen (polysaccharide) → glucose

   • Released into BS

2. Increased diameter of bronchi + bronchioles

   • More O2 delivered to blood

3. Ventilation rate + tidal volume increase

4. SA node (pacemaker) increases heart rate

   • More glucose + O2 delivered via blood

5. Vasodilation → increase blood flow to liver + muscles

   • Muscle → movement

   • Liver → glycogen store

6. Vasoconstriction → decrease blood flow to gut + kidneys

   • No need to digest food

Why is it important to increase the blood flow to liver during fight or flight?

• Liver = glycogen store

• Glycogen → glucose

• More blood to liver → can pick up more glucose → then send to muscles

What do the effects of adrenaline facilitate?

Intense muscle contraction

What is the endocrine system controlled by?

Hypothalamus + pituitary gland

• Hypothalamus sends signals to PG

What is the hypothalamus connected to?

Pituitary gland

What do the hypothalamus connect?

Connect the nervous + endocrine system

Structure of pituitary gland

2 lobes

• Anterior

• Posterior

Hypothalamus

• Acts as a homeostatic control centre

• Regulates hormonal secretion via the pituitary gland

• Receives inputs from many sources

• Changes input (nervous signalling) → output (hormonal signalling)

Examples of sources where the hypothalamus receives (nervous) inputs from?

1. Other parts of the brain

2. Sensors for:

   • Temp

   • Blood glucose

   • Solute concentrations

INPUT (NERVOUS SIGNALLING) → OUTPUT (HORMONES)

Input vs output via the hypothalamus

1. Input- nervous signalling

2. Output- hormonal signalling (hormones)

Osmoregulation

Regulates osmolarity / solute concentration of blood

Role of hypothalamus in osmoregulation (how it connects nervous system to endocrine system)

H = hypothalamus

1. H recieves info from sensory organs (about blood solute conc) (nervous)

2. Eg solute conc too high →

3. Prompts PG to release ADH (hormone)

4. Increases reabsorbption of water in kidneys

How does the hypothalamus interpret hormonal info, eg during puberty?

1. Puberty → H releases GnRH

2. Travels to PG

3. Causes PG to release LH + FSH

4. Initiates puberty

Where is the SA (pacemaker) node located?

Right atrium of the heart

• SA = sinoatrial node

What does the SA node control?

Heart beat (rate)

What is the SA node connected to in the brain?

SA node connected to medulla oblongata

What nerves connect the SA node to medulla oblongata?

• Vagus nerves

• Sympathetic nerves

Nerves transmit info from medulla to SA node

Effect of sympathetic vs vagus nerve on SA node

…causes SA node to:

1. Sympathetic- increase heart rate

2. Vagus- decrease heart rate

What is the SA node in feedback loops with?

1. Chemoreceptors

2. Baroreceptors

Chemoreceptors

Monitor:

• Blood pH

• O2 conc

• CO2 conc

Location of chemoreceptors

1. Aorta

2. Carotid arteries

Baroreceptors

Monitor blood pressure

Location of baroreceptors

1. Aorta

2. Carotid arteries

General function of these receptors (baro, chemo)

Send input to the medulla in the brainstem

What does the medulla do with the input sent by receptors?

Coordinates the response by sending nerve impulses to the heart to adjust:

• Heart rate

• Stroke volume

How do chemoreceptors sense CO2 conc?

Chemoreceptors sense low pH = high CO2 conc

What needs to happen when chemoreceptors sense high CO2 conc (low pH) + why?

Increase heart rate → so can pump blood rich in CO2 to the lungs → remove CO2 via ventillation

When there is high CO2 conc (low pH), how does the medulla increase HR?

1. Medulla oblongata sends msg via sympathetic nerve to SA node to increase heart rate

2. pH returns to norm → M sends msg via vagus nerve to decrease HR

What happens when baroreceptors sense blood pressure is too low?

Changes occur that tell SA node to increase HR

What can override baro + chemo receptors?

Epinepherine

What causes blood pH changes?

1. ↑ activity = ↑ muscle movement → need ↑ ATP

2. So ↑ respiration

3. CO2 = product of respiration → ↑ CO2 (dissolves w water in blood plasma)

4. So ↓ pH

Muscles controlling ventilation (breathing)

• Diaphragm

• Intercostal muscles

What happens when blood pH decreases?

1. Chemoreceptors in brainstem sense pH changes

2. (medulla) Send nerve signals to diaphgram + intercostal muscles

3. Causes ventilation rate to increase

4. Restores normal pH

Is feedback control of ventilation rate following sensory input from chemoreceptors a negative or positive loop?

Negative

• Bc when blood pH returns to normal homeostatic levels, breathing rate decreases

What monitors blood pH changes?

Chemoreceptors in the brainstem

What do chemoreceptors in the brainstem control?

Ventilation rate using signals to the diaphragm + intercostal muscles

2 types of nervous system that control digestion

1. Central nervous system (CNS)

2. Enteric nervous system (ENS)

Peristalsis

Involuntary wave of muscle contractions that move food thru the digestive tract + stomach

Voluntary parts of digestive system movements

1. Initiation of swallowing food

2. Egestion of faeces

What are voluntary movements controlled by?

Eg:

• Initiation of swallowing of food

• Egestion of faeces

CNS

Involuntary parts of digestive system movements

Peristalsis

• Betw initiation + egestion

What are involuntary movements in the digestive system controlled by?

Eg:

• Peristalsis

Enteric nervous system (ENS)