integration of body systems

tissue

a group of specialised cells that work together to perform a specific function

alveolar type one

• make up 95% of respiratory surface

• allow for gas exchange

• extensive but very thin (flattened) - large SA:V

alveolar type 2

• cuboidal

• secrete surfactant that reduces surface tension and prevents collapse

organ

a group of tissues that work together to perform a specific function in the body.

spongy mesophyll

adapted for gas exchange

palisade mesophyll

adapted for photosynthesis

• full of chloroplasts

organ systems

groups of organs that work together to perform complex functions in the body.

organism

a living individual made up of interconnected parts

hormonal signalling

• endocrine system

• chemical

• widespread

• bloodstream

• affects target cells

• long term

• slow

neural signalling

• nervous system

• neurons

• electrical

• rapid

• highly focused

• short term

• muscle contractions

similarities between neural signalling and hormonal signalling

used for internal communication

circulatory system

transports materials and energy between organs

• also removes waste products such as CO2 in respiration

brain

central information integration organ

• receives, processes, stores and sand sends instructions to all body parts

memory

capacity to store information

where does the brain get information from

specialised sense organs (eyes) and sensory receptors (pressure receptors in the blood vessels)

CNS

central nervous signalling

brain and spinal cord

spinal cord matter

white matter: contains myelinated axons which transport signals from sensory organs to the brain

grey matter: contains motor neurons and relay neurons

conscious processes

• only performed when awake

• performed voluntarily - decision is made

• contraction of striated muscle (attached to bones) can be consciously controlled, allowing for deliberate movement

• coordinated only by the cerebral hemispheres of the brain

example of a conscious process

initiation of swallowing when food is pushed from the mouth cavity to the pharynx

unconscious processes

• when awake or sleep

• involuntarily

• secretion by glands and contractions of smooth muscle (not attached to bones)

• coordinated by brain and spinal cord

example of unconscious processes

swallowing food once it has entered the oesophagus

vomiting when stomach contents are regurgitated

striated muscle

attached to bones

• used for locomotion and posture

• conscious control of movements

• receives signals from the primary motor cortex via motor neurons

reflex

rapid, involuntary response to a specific stimulus

• signals pass through the smallest number of neurons

  • prevents harm

receptors

• sense a stimulus (change in conditions) known as a stimulus

• using receptors or nerve endings (pain and heat)

sensory neurons

receive signals from sensory receptors and pass to CNS

• using long axons which end in synapses with relay neurons

interneurons

located within the CNS

make decisions

motor neurons

if threshold potential is reached, they transmit signals to effectors

types of effectors

muscles and glands m

muscle

respond to signals by contracting

glands

respond by secreting

cerebellum

part of brain responsible for balance, coordinations and skeletal muscle contractions

• helps with posture and memory

circadian rhythms

24 hour cycles which human behaviour is adapted for

• controlled by an internal system

what cells does the circadian rhythm depend on

suprachiasmatic nuclei (SCN)

• in the brain, they control the secretion of the hormone melatonin

melantonin

controls circadian rhythm (sleep wake cycle)

• hormone secreted by pineal gland

• high levels cause drowsiness, promote sleep and lowers body temperature

• low levels cause wakefulness

epinephrine

aka → adrenaline

a hormone that prepares the body for vigourous activity

secreted by the adrenal glands and binds to adrenergic receptors in the plasma membrane of target cells

effect of epinephrine

• muscle cells break down glycogen into glucose, which can be used in aerobic or anaerobic respiration

• liver cells also break down glycogen into glucose, which is released into the bloodstream

• bronchi and bronchioles dilate due to relaxation of smooth muscle cells - airways are wider + ventilation is easier

• ventilation rate increases so a larger total volume air is breathed in and out per minute

• sinoatrial node speeds up heart rate, so cardiac output increases

• vasodilation to arterioles that carry blood to muscles and livers, more blood

• vasoconstriction to gut, kidneys, skin and extremities, less blood

hypothalamus: linking

nervous system to endocrine system via the pituitary gland

processes that depend on the system integration of the hypothalamus and the pituitary gland

osmoregulation: osmoreceptors in the hypothalamus detect blood osmolarity changes, and axons transport ADH to the pituitary gland, where it is secreted into bloodstream

puberty: hypothalamus secretes GnRH, a neurohormone that stimulates the secretion of FSH and LH by the pituitary glands

sinoatrial node

cardiac muscles cells in the right atrium that ask as a pacemaker for the heartbeat

where does the pacemaker recieve signals from

the cardiovascular centre, in the medulla oblongata of the brain

signals from sympathetic nerve

causes the pacemaker to increase the frequency of heartbeats

signals from vagus nerve

causes the pacemaker to decrease the heart rate

baroreceptors

are sensory receptors in the wall of the aorta and carotid arteries that monitor blood pressure

• allows the control of blood pressure through negative feedback loops

  • low blood pressure → increase in heart rate which increases blood pressure

  • high blood pressure → decrease in heart rate which decreases blood pressure

chemoreceptors

some monitor blood oxygen concentration and other monitor blood pH (which varies with CO2 concentration

• low oxygen + low pH → increase heart rate increases blood flow to tissues so more oxygen is delivered and more CO2 is removed

• high oxygen + high pH → decrease in heart rate

normal range of blood pH

7.35 to 7.45

acidosis

when CO2 concentration is too high, causing a decrease in pH

ventiliation rate control

1. increase in CO2 concentration leads to a decrease in CO2 concentration

2. chemoreceptors detect this decrease and send signals to the respiratory centre

3. causes a decrease the interval between breaths to increase ventilation rate.

two layers of the gut wall

• both are smooth muscle

  • outer layer is longitudinal and the inner layer is circular.

peristalsis

waves of contractions moves food along the intestine

controlled by the ENS w/o inputs from the CNS

one direction only → away from the mouth

function: churn semi-digested food to mix it with enzymes and speed up digestion

vomiting

abdominal muscles are used rather than circular and longitudinal muscle

example of a gut movement controlled by the ENS but is voluntary

defecation → removal of faeces from rectum via the anus