biology part 2 Flashcards
specialised cells (plant cells) - end
what is the function of palisade cells
they specialise in food manufacturing
what is the structure of a palisade cell
- Cylindrical shaped
- Packed tightly in the upper part of the leaf
- contains chloroplast to capture energy from photosynthesis
- large vacuole to help keep the cell and structure rigid
what is the function of a root hair cell
absorbs water and dissolved minerals from the soil (active transport)
what is the structure of the root hair cell
- large surface area for active transport
- contains mitochondria to help supply energy for active transport.
- thin wall to absorb water
- long extension that goes into the soil
what is the structure and function of the xylem
- found in roots, stems and leaves
- helps support plants.
- hardened cell wall
- transports water by capillary action
what is the structure and function of phloem
- found in roots, stems and leaves
- supplies energy or transportation of sugars from photosynthesis
what is the structure of guard cells
- thin outer walls and thicker inner walls to open and close
- sensitive to light and close at night to save water without missing out on photosynthesis
what is the function of guard cells
-adapted to open and close the stomata in the leaf.
-if the plant has lots of water the cell will fill with water and turgid (swollen) in order to make the stomata open for gas exchange for photosynthesis
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what is the epithelial tissue
covers the external surfaces of organs eg skin and the lining on the internal organs.
what are connective tissues
provide support to epithelial tissue and skeletal system
what is the muscle tissue
used for movement
what is the nervous tissue
controls all of the body (voluntary and involuntary)
name the 4 types of tissue
- epithelial
- connective
- muscle
- nervous
what is a tissue
group of cells similar in structure and carry out related functions
name where the epithelial tissue is found
- skin
- respiratory tract
- digestive tract
- urinary tract
what is the squamous epithelial tissue
- covers a body surface or internal organs like lungs.
- nearly all substances received/given off by the body must pass through an epithelium layer.
- supplied by blood vessels.
- are continually being replaced.
- very flat and thin with egg shaped nuclei
- one cell thick
- good force surfaces where diffusion occurs
what is the function of the squamous epithelial tissue
protection, secretion, absorption, filtration, excretion and sensory reception
what is the structure of the red blood cells
- concave shape for big surface area to help diffusion between oxygen and co2 helping them pass smoothly through capillaries.
- packed with haemoglobin which absorbs oxygen.
- no nucleus so there’s more room for haemoglobin
- made in the bone marrow
- shape allows them to squeeze through blood vessels
what is the function of the red blood cells
-adapted to carry oxygen
what is the structure and function of the sperm
- the head (acrosome) contains enzymes that digest the outer layers of the egg cell.
- the haploid nucleus contains one set of chromosomes.
- undulipodium for movement to swim to the egg.
- Mid-region has mitochondria to provide energy for movement.
what the structure and function of the egg
- the haploid nucleus contains half of the chromosomes.
- special vesicles contain a substance that helps stop more than one sperm from fertilising the egg.
- cytoplasm is full of energy-rich material.
- follicle cells supply vital proteins.
- zona pellucida (jelly layer) stops more than one sperm from fertilising the egg.
what is the structure and function of white blood cells
- large nucleus and is made in the bone marrow and lymph nodes.
- two types are phagocytes and lymphocytes
What is the columnar epithelium
- the upper airway (trachea and bronchi) is lined with ciliates epithelium cells
- the cells have a lot of mitochondria
- the cilia in the epithelium move mucus away from the lungs, preventing inhaled particles causing infections
What is chronic obstructive pulmonary disease (COPD)
- more common in smokers as substances in smoke damages the lungs
- smoke causes the cilia of the columnar epithelium to slow down and stop beating and eventually dies off so mucus builds up.
- clogs the airways and causes coughing that ruptures the thin alveolar epithelial cells reducing the surface area for gas exchange
- provides good environment for pathogens to grow
What is endothelial tissue
- endothelial tissue lined the inside of the blood vessels. It is made from a single layer of flat, long cells
- their function is to provide a smooth surface so that blood flows smoothly and easily
What is atherosclerosis
- a disease that leads to CHD and strokes
- fatty deposits can either block an artery directly or increase its chances of being blocked by blood clot
- cigarette smoke contains many toxic chemicals that lead to this
- thickness of the blood increases and causes fatty deposits to build up on the walls of the arteries.
- smoking increases blood pressure and heart rate which causes damage to the endothelium
What is a muscle
Muscles are made up of bundles of cells called muscle fibres. The fibres are made up of myofibrils
What is myofibril
Made up of actin and myosin filaments
What is sarcomere
Repeated units of actin and myosin filaments. This is the basic unit for muscle contraction
What is the order in myofibril, sacromere, muscle and bundle of muscle fibres
Muscle —— bundle of muscle fibres ——— myofibril ——— sacromere (actin and myosin)
What are muscles made from
Thick protein filament made from the protein myosin and the thin filament of actin.
What happens when a muscle contraction takes place
The actin filaments move between the myosin filaments, shortening the length of the sacromere and the length of the muscle
What is a slow twitch muscle fibre
- slow
- contracts for a long period of exercise
- supplies mitochondria from aerobic respiration (oxygen)
- lots of capillaries
- doesn’t tire easily
- large oxygen and glucose stores
what is a fast twitch muscle fibre
- rapid intense contractions in short bursts.
- few mitochondria from anaerobic respiration (no oxygen)
- few capillaries
- tires easily
- little glucose and oxygen stores
what are nerves
- made up of neurones
- carries messages in the form of electronic signals from one part of the body to another.
- the messages are known as nerve impulses
what is the structure of the nervous system
it is broken down into two parts, the peripheral nervous system and the central nervous system which consists of the brain and spinal cord.
what is the structure of a neurone
-cell body
-nucleus
-dendrite (finger-like things around the nucleus)
schwann cell (inside bit of the tail)
-myelin sheaths (outside bit of the tail)
-node of Ranvier (the connecting bit that connects two Schwann cells)
-axon terminals (the bit that attaches to the dendrite)
what is the function of the cell body
contains the nucleus and is where all the materials needed by the cell are made
what is the function of the axon
adapted to conduct an electric impulse called an action potential
what is the function of the dendrite
receives chemical signals from the axon terminal to other neurons
what is the function of Schwann cell
Produces myelin sheaths
what is the function of the node of Ranvier
gaps in the myelin sheath, they allow the electrical impulse to pick up speed
what are nerves that arent myelinated
they are responsible for transmitting pain such as aches and soreness rather than sharp pain and detects a temperature change.
what is a non-myelinated nerves function
- dont have a myelin sheath
- grey
- transmits impulses slower
- dont have nodes of Ranvier
what is a myelinated nerves function
- have a myelin sheath
- white
- transmit impulses very fast
- do have nodes of Ranvier
what are the 3 types of neurones
- sensory neurones
- relay neurones
- motor neurones
what is an action potential
neurones send electric impulses which are generated by the concentration of ions inside and outside of the nerve cell causing a potential difference which is known as an action potential which transmits an electrical signal between nerve cells.
what is a sensory neurone
connects sensory receptors to the central nervous system (CNS)
what is a relay neurone
found in the central nervous system (connects sensory neurones to motor)
what is a motor neurone
communicates from CNS to effectors
why cant a new action potential be generated in the same section of membrane for 5 milliseconds
to ensure yhst the impluse travels in one direction along a nerve fibre. between the action potentials the cell is at resting potential.
what is the action potential triggered by
it is triggered the depolarisation of nearby membrane changing the potential difference to the threshold potential.
what will happen if the threshold potential isnt reached
if it isnt reached nothing will happen
what is depolarisation in the nerve
- sodium gates open
- sodium diffuses into the cell carrying a positive charge
- sodium gates close.
what is repolarisation in the nerve
- potassium gates open
- potassium diffuses out of the cell taking positive charge with it.
- potassium gates close
what is recovery in the nerve
- potassium moves back into the cell through non-voltage-gated channels
- attached by negative charges as hyperplolarised
- rested potential equilibrium restored
what is the saltatory conduction
- the only region of a myelinated nerve fibre that can be depolarised is at the nodes of Ranvier where there is no myelin.
- meaning that the nerve impluses can travel a longer distance and that they can travel faster without myelin.
- the impulse ‘jumps’ from one node to the next.`
what are ElectroCardiograms (ECG)
- it measures the action potentials of the heart.
- electrons are placed on different parts of the body to detect electrical impulses.
- the machine amplifies the impulses during each heartbeat and records them.
what does the P wave
- the time of atrial systole (contraction)
- depolarisation of the atria (upper chambers of the heart) so they contract
what does the QRS complex
- the time of the ventricular systole (contraction
- depolarisation of the ventricles so they contract
what does the T wave
- caused by repolarisation of the ventricles during diastole (relaxation and recovery)
- repolarisation of the ventricles (recovery)
