Movement in the Body Flashcards
What generates movement in the body
Molecular motors
Describe how a skeletal muscle produces movement of the hand
- Cross bridges form between actin and myosin filaments. 2. The relative position of the filaments changes. 3. The sarcomeres shorten. 4. The length of the muscle fibre shortens. 5. The muscle enters a state of contraction. 6. The position of the tendon changes. 7. Movement of the hand follows
By which method does water move in and out of cells
By passive diffusion through the plasma membrane
What are aquaporins
Intrinsic membrane proteins that form pores in the membranes. Water is actively transported across the plasma membrane through aquaporins.
What are 3 uses of molecular motors
- movement of water in and out of cells 2. Ion channels and pumps 3. Axoplasmic transport
What are ion channels and pumps
Complex units made up of sub units. They allow specific ions to enter and exit cells
What is axoplasmic transport used for
Moving large molecules, organelles, secretory vesicles and particles around a cell
Give an example of axoplasmic transport
- mRNA moves out of the nucleus into RER 2. Neurotransmitter vesicles travel down the axon
State 3 examples where movement is a part of growth
- Hair 2. Growth and remodelling of the skeleton (changes in size and shape) 3. Growth of neurones in plasticity
How is growth by movement achieved
By molecular synthesis
How do substances move between cells
- Intercellular junctions (gap junctions) 2. Synapses
Which two types of cells have gap junctions
Smooth muscle cells and cardiac muscle cells
Give an example of a single cell which can move
Spermatozoa
How do macrophages defend against the body
They move to where they are needed (like microglia in the brain)
How many skeletal muscles are there in the human body
500
Why are there many different types of skeletal muscle
So that they are adapted to their function
What are motor units
The basis of neuromuscular control
Define a motor unit
The skeletal muscle fibres innervated by a single motorneurone
Describe how the number of muscle fibres in a motor unit depends on the activity that an individual muscle has to perform
Muscles for fine (delicate) movement = small motor units. Muscles for coarse (simple) movements = big motor units
There are different types of muscle fibres in the same motor unit- true/false
False- they are all made up of the same fibre e.g. all type 2
How is the tension of a muscle produced
By the shortening of the myofilaments in a sacromere
How is the tension transferred to the bone
By connective tissues in the muscle and the tendon attaching to the bone
What is an isotonic contraction
Tension remains constant as the muscle changes in length
What is an isometric contraction
Muscle does not shorten and the tension remains at constant muscle length
What type of contraction occurs when muscle tension is sufficient to overcome the weight of an object in your hand, the muscle shortens and you are able to lift the object
Isotonic contraction
What type of contraction occurs hen the object of too heavy to lift, the muscle cannot shorten but tension remains
Isometric contraction
What type of muscle is cardiac muscle as so what contractile mechanism occurs
Striated muscle so contractile mechanism is the same as skeletal muscle
Why are the movements of the heart very different to that of skeletal muscle
They heart acts as a pump and so contractions are aided by valves to ensure blood is pumped only in one direction
What unit of time is used to measure skeletal muscle contraction
Milliseconds
What unit of time is used to measure smooth muscle contractions
Seconds
Give examples of smooth muscle contractions
- Contraction of blood vessels to assist the circulation. 2. Contraction of GI tract to push ingested food along. 3. Distension of the urinary bladder as it fills, 4. Constriction of the pupil. 5. Contraction of the vans deferens during ejaculation of seminal fluid. 6. Growth and contraction of the uterus during pregnancy and birth. 7. Goose pimples in the skin when cold
How is the smooth muscle able to produce such a wide range/ speed/ force of movemenr
Due to the spatial arrangement of the smooth muscle cells and the innervation
Give examples of the ways smooth muscle cells can be different
- In orientation- layers, bundles, rings, helices, meshes. 2. Amount of supporting elements- collagen, elastin fibres. 3. Varied proportions of smooth muscle cells and supporting elements
Why doesn’t the bladder burst when its so full
The structural relationship between the smooth muscle cells and the extracellular components
What is the volume of an empty human bladder
100ml
What is the usual size of a bladder when emptied
300-350ml
What is the maximum capacity of the bladder
How are smooth muscle cells arranged
In layers
What is a major difference between smooth and skeletal muscle cells
Skeletal muscle cells are attached to tendons and bones and the contractile force produces by the muscle is transmitted to these skeletal structures to produce movements of the body. Smooth muscles are not attached to any skeletal structures only to other parts of the organs they occur in. The hardening of smooth muscles as they contract acts like a supporting skeleton over which the rest of the muscle can move
What is hypertrophy
Increase in cell size
When can smooth muscle cells undergo hypertrophy
In response to pressure
What happens to the the uterus during pressure
Hypertrophy of the smooth muscle cells in the wall of the uterus. AND hypertrophy of the smooth muscle cells in the uterine artery. After birth everything returns to normal.
